tag:blogger.com,1999:blog-37815834593284365252024-02-08T02:14:02.202-08:00Reading and Word Recognition ResearchLivia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.comBlogger34125tag:blogger.com,1999:blog-3781583459328436525.post-57217459238235633242011-05-18T20:18:00.000-07:002011-05-18T20:18:35.608-07:00N1 Specialization in Children with Dyslexia<b>Accessibility:</b> Advanced <br />
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It's been a little while, but we've been talking about the N1 component and how it relates to reading. Just to recap, the N1 component is an ERP component occurring at around 170 ms. In normal reading adults, the component is <a href="http://wordresearch.liviablackburne.com/2011/04/introduction-to-n170-response-to-words.html">stronger for words than for symbols</a>. We will refer to the words minus symbols difference as “N1 specialization for words .” <a href="http://wordresearch.liviablackburne.com/2011/04/n1-component-in-prereading-children.html">Pre-reading kindergartners</a> do not have this N1 specialization, while <a href="http://wordresearch.liviablackburne.com/2011/04/n1-component-in-second-graders.html">second graders</a> have a stronger N1 specialization compared to adults. Today we focus on children with dyslexia. <br />
As you might've guessed, Maurer and colleagues did the same experiment on children with dyslexia as well (see <a href="http://wordresearch.liviablackburne.com/2011/04/introduction-to-n170-response-to-words.html">previous article</a> for more information on what they did). These are the findings:<br />
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1. N1 specialization for words over symbols was much reduced in dyslexic second graders compared to normal reading second graders. <br />
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2. N1 specialization correlated with reading speed in second graders.<br />
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3. Interestingly, although dyslexic second graders had reduced specialization, they actually had a greater specialization two years earlier (in kindergarten) than their normal reading counterparts. I'm not quite sure why this would be.<br />
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4. In addition to the N1 difference, there was also a reduced response in the earlier P1 component in children with dyslexia (at both ages – kindergarten and second grade). This reduction was general for both words and symbols though, and not specialized to words. <br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Brain+%3A+a+journal+of+neurology&rft_id=info%3Apmid%2F17728359&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Impaired+tuning+of+a+fast+occipito-temporal+response+for+print+in+dyslexic+children+learning+to+read.&rft.issn=0006-8950&rft.date=2007&rft.volume=130&rft.issue=Pt+12&rft.spage=3200&rft.epage=10&rft.artnum=&rft.au=Maurer+U&rft.au=Brem+S&rft.au=Bucher+K&rft.au=Kranz+F&rft.au=Benz+R&rft.au=Steinhausen+HC&rft.au=Brandeis+D&rfe_dat=bpr3.included=1;bpr3.tags=Medicine%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology%2C+Neurology">Maurer U, Brem S, Bucher K, Kranz F, Benz R, Steinhausen HC, & Brandeis D (2007). Impaired tuning of a fast occipito-temporal response for print in dyslexic children learning to read. <span style="font-style: italic;">Brain : a journal of neurology, 130</span> (Pt 12), 3200-10 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/17728359" rev="review">17728359</a></span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-45985771744195928842011-04-12T12:00:00.000-07:002011-04-12T12:00:27.873-07:00The N1 Component in Second Graders<b>Accessibility:</b> Advanced<br />
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Last week, we learned that the N1 component in <a href="http://wordresearch.liviablackburne.com/2011/04/introduction-to-n170-response-to-words.html">normal reading adults</a> differentiated between words and symbols, while the N1 component in <a href="http://wordresearch.liviablackburne.com/2011/04/n1-component-in-prereading-children.html">pre-reading kindergartners</a> did not. The question now is, at what point in development does N1 component start resembling that of adults? Maurer and colleagues tested the same kindergartners from their <a href="http://wordresearch.liviablackburne.com/2011/04/n1-component-in-prereading-children.html">2005 paper </a>when the kids were in second grade to see how their brain activity changed after two years of reading instruction.<br />
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These were their findings:<br />
1. The N1 component differentiates between words and simple strings in the second graders.<br />
2. Second graders actually had a greater words/symbols N1 difference than adults.*<br />
3. There is a correlation between N1 specialization and reading fluency. In other words, the difference in N1 amplitude between words and symbols was correlated with faster reading in the second graders.<br />
4. The N1 negativity was more left lateralized in adults than in children. The N1 topography was bilateral for 2nd graders, and right lateralized in kindergareners.<br />
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Conclusions: Two years of reading instruction is enough for the brain to start differentiating between words and meaningless symbols. In terms of the development of N1 specialization, there are hints of a U shaped curve, with 2nd graders displaying even greater word/symbol differences than adults.<br />
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* Amplitudes in general were bigger in the second graders, but the difference held when amplitudes were normalized between children and adults<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=NeuroImage&rft_id=info%3Apmid%2F16920367&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Coarse+neural+tuning+for+print+peaks+when+children+learn+to+read.&rft.issn=1053-8119&rft.date=2006&rft.volume=33&rft.issue=2&rft.spage=749&rft.epage=58&rft.artnum=&rft.au=Maurer+U&rft.au=Brem+S&rft.au=Kranz+F&rft.au=Bucher+K&rft.au=Benz+R&rft.au=Halder+P&rft.au=Steinhausen+HC&rft.au=Brandeis+D&rfe_dat=bpr3.included=1;bpr3.tags=Neuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience">Maurer U, Brem S, Kranz F, Bucher K, Benz R, Halder P, Steinhausen HC, & Brandeis D (2006). Coarse neural tuning for print peaks when children learn to read. <span style="font-style: italic;">NeuroImage, 33</span> (2), 749-58 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/16920367" rev="review">16920367</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com1tag:blogger.com,1999:blog-3781583459328436525.post-62867843882367365282011-04-08T08:00:00.000-07:002011-04-08T08:00:21.307-07:00The N1 Component in Prereading Children<b>Accessibility</b>: Intermediate-Advanced<br />
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Just to recap from the <a href="http://wordresearch.liviablackburne.com/2011/04/introduction-to-n170-response-to-words.html">last article</a>, the N170 is an ERP component that differentiates between words and symbol strings in normal reading adults. This the specialization developed after learning to read, or does it have something to do with the visual properties of symbols? <br />
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Maurer and colleagues tested pre-reading kindergartners to see whether the specialization is there before they learn to read. They had kids perform the same task as adults (looking at a series of words, pseudowords, symbol strings, and pictures).<br />
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They found several things:<br />
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1. Adults again had the same N170 (called N1 in this paper), which was stronger for words than symbols.<br />
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2. Kids also had an N1, but it was later, had a larger amplitude, and most importantly, did not distinguish between words and symbols, suggesting that this N1 specialization stems from experience with words.<br />
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3. Some of the kids, the ones with high letter knowledge, did have an N1 that differentiated between letters and symbols. However, the pattern was different from adults. While adults had the strongest effect on the left side of the brain, these children showed an effect on the right side.<br />
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So in conclusion, the N1 specialization seems to be related to reading. However, there seem to be some intermediate steps in the development of the specialization. At least in an early stage, the right hemisphere is involved, and then the processing becomes more left lateralized.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+cognitive+neuroscience&rft_id=info%3Apmid%2F16269095&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Emerging+neurophysiological+specialization+for+letter+strings.&rft.issn=0898-929X&rft.date=2005&rft.volume=17&rft.issue=10&rft.spage=1532&rft.epage=52&rft.artnum=&rft.au=Maurer+U&rft.au=Brem+S&rft.au=Bucher+K&rft.au=Brandeis+D&rfe_dat=bpr3.included=1;bpr3.tags=Neuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience">Maurer U, Brem S, Bucher K, & Brandeis D (2005). Emerging neurophysiological specialization for letter strings. <span style="font-style: italic;">Journal of cognitive neuroscience, 17</span> (10), 1532-52 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/16269095" rev="review">16269095</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-18671919114901220682011-04-07T12:00:00.000-07:002011-04-07T12:00:52.638-07:00Introduction to the N170 Response to Words<b>Accessibility: Intermediate-Advanced</b><br />
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This month is N170 month. I'm going to be going through a bunch of papers by Urs Maurer on the N170 ERP component and how it relates to word processing. EEG is not my specialty, so hopefully I won't mess anything up.<br />
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For this post, we'll start with the basics. The N170 is an<a href="http://en.wikipedia.org/wiki/Event-related_potential"> ERP component </a>measured in EEG experiments. The N means that it is a negative potential, and the 170 means that it peaks roughly at around 170 ms, although the timing can vary. The N170 tends to be elicited by certain categories of visual images (like faces), and is enhanced for categories for which the subject has some expertise (for example, enhanced N170 response for bird experts when viewing birds).<br />
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This last characteristic makes the N170 helpful for studying word processing. Urs Maurer and colleagues tested adults by showing them words, pseudowords, and symbol strings*. The adults showed a greater N170 to words than symbol strings, which would be consistent with an expertise for words acquired over years of reading. The N170 was also more left lateralized for words than to symbol strings, which is not surprising given the general left lateralization of language. Also, the N170 seems to be stronger over the inferior occipital temporal channels, close to the visual word form area.<br />
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So those are the basics for the N170 in normal reading adults. It's a useful tool for studying word processing in populations like children and people with dyslexia, so that is where we will continue.<br />
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*the task was to detect repetitions<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Behavioral+and+brain+functions+%3A+BBF&rft_id=info%3Apmid%2F16091138&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Fast%2C+visual+specialization+for+reading+in+English+revealed+by+the+topography+of+the+N170+ERP+response.&rft.issn=&rft.date=2005&rft.volume=1&rft.issue=&rft.spage=13&rft.epage=&rft.artnum=&rft.au=Maurer+U&rft.au=Brandeis+D&rft.au=McCandliss+BD&rfe_dat=bpr3.included=1;bpr3.tags=Neuroscience%2CCognitive+Neuroscience">Maurer U, Brandeis D, & McCandliss BD (2005). Fast, visual specialization for reading in English revealed by the topography of the N170 ERP response. <span style="font-style: italic;">Behavioral and brain functions : BBF, 1</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/16091138" rev="review">16091138</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-53986035034954367022011-02-27T20:02:00.000-08:002011-03-11T07:52:14.074-08:00Brain Measures Predict Future Improvement in Children With Dyslexia<b>Accessibility:</b> Intermediate<br />
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Disclaimer: My PI is an author on this paper.<br />
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There is a lot of variability in outcomes for children diagnosed with dyslexia. Some children improve greatly over time, while others don't. Today, we're looking at a paper that asks whether it's possible to predict improvement in children with dyslexia. <br />
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Fumiko Hoeft and colleagues scanned children with and without dyslexia while performing a word rhyme task. They also tested the children on several reading measures. Two and half years later, they retested the children again on the same reading measures. Some of the children improved, while others didn't . The question then, is whether there is something from the brain scans or test scores in the first session that can predict performance 2 1/2 years later.<br />
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The researchers found two brain measures that predicted improvement in reading skills: greater white matter integrity in the right superior longitudinal fasciculus, and activation in the right inferior frontal gyrus during the rhyming task. Note that these regions are not your typical language regions. In fact, they are the right hemisphere counterparts of language processing regions in typical readers. Also, these didn’t correlate with reading improvement in control readers.This suggests that rather than imitating what typical readers are doing, the dyslexics who improve are bringing in compensatory mechanisms. <br />
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So if we have a dyslexic child, how accurately can we predict future improvement? The researchers found that brain data from those two regions by themselves predicted reading gains with 72% accuracy. When the researchers used data from the entire brain, they predicted reading gains with 90% accuracy. (Chance would be 50%. The researchers were trying to predict whether a child’s improvement was below or above the median improvement for the entire group.)<br />
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These results are an interesting case of brain data giving us more information the behavioral measures. None of the behavioral measures predicted which children would improve, but the brain data did. <br />
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One might ask how useful these results would be for dyslexics. On the one hand, any information is helpful. On the other, if you are in the group predicted to not show improvements, would you really want to know? One good thing about this type of research is that perhaps if we keep going in this direction, we might be able to not only predict improvement, but predict improvement to different types of interventions, thus leading to better treatment.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft_id=info%3Apmid%2F21173250&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Neural+systems+predicting+long-term+outcome+in+dyslexia.&rft.issn=0027-8424&rft.date=2011&rft.volume=108&rft.issue=1&rft.spage=361&rft.epage=6&rft.artnum=&rft.au=Hoeft+F&rft.au=McCandliss+BD&rft.au=Black+JM&rft.au=Gantman+A&rft.au=Zakerani+N&rft.au=Hulme+C&rft.au=Lyytinen+H&rft.au=Whitfield-Gabrieli+S&rft.au=Glover+GH&rft.au=Reiss+AL&rft.au=Gabrieli+JD&rfe_dat=bpr3.included=1;bpr3.tags=Medicine%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Neurology">Hoeft F, McCandliss BD, Black JM, Gantman A, Zakerani N, Hulme C, Lyytinen H, Whitfield-Gabrieli S, Glover GH, Reiss AL, & Gabrieli JD (2011). Neural systems predicting long-term outcome in dyslexia. <span style="font-style: italic;">Proceedings of the National Academy of Sciences of the United States of America, 108</span> (1), 361-6 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/21173250" rev="review">21173250</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com7tag:blogger.com,1999:blog-3781583459328436525.post-9643614915217161642011-01-27T15:54:00.000-08:002011-03-11T07:50:35.945-08:00Don't Assume that fMRI and MEG Will Give You Comparable Results<b>Accessibility</b>: Intermediate/Advanced<br />
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There are three common methods of studying brain function in normal human populations: fMRI, MEG, an EEG. There is surprisingly little crosstalk between the techniques, mostly due to practical issues.For better or worse, labs tend to specialize in one technology. <br />
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It's often assumed that the relationship with techniques is straightforward, that it's simple to map results from one technique onto another. However, a recent study by Johanna Vartianen and colleagues suggests otherwise.<br />
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The group wanted to study reading using all three brain techniques. Participants performed the same experimental paradigm twice: once with simultaneous EEG and fMRI, and once with simultaneous EEG and MEG. Participants saw words, pseudowords, consonant strings, and symbol strings, and words embedded in noise. Their task was to detect immediate repetitions. The EEG results from the two sessions were comparable, so the researchers went on to compare the fMRI and MEG activation patterns for the experiment.<br />
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To summarize, activation patterns between MEG and fMRI did not show a straightforward relationship. In some regions, the two techniques showed the same pattern. For example, in the occipital lobe, both MEG and fMRI measures had more activation to noisy words than other types of stimuli.<br />
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If you look at the occipitaltemporal lobe however, the two techniques had opposite results. MEG showed more activation to real letters than symbols, while FMRI showed more activation to symbols then letters. <br />
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In the left frontal cortex the two regions had completely different patterns. FMRI activation was higher for words and pseudowords than symbols and noisy words. The MEG results showed no difference at all between stimulus types.<br />
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I guess this is one of these results that you don't see going in, but in hindsight make you hit yourself over the head. FMRI and MEG measure very different things, so it’s entirely possible that results would come out differently. FMRI measures cerebral blood flow on a timescale of several seconds, while MEG measures synchronous electrical activation with millisecond resolution. So ( as the authors suggest) non-synchronous activity may be lost in MEG. Meanwhile, fMRI picks up average activity over a longer time period and may miss short-term activity.<br />
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Interestingly, the authers mentioned that previous MEG results for the visual word form area were fairly robust to task differences, while fMRI results do seem to vary with task. Now I don't know the MEG literature well, but they're certainly right about the fMRI literature. In that case, I wonder what it is about the MEG that makes its results relatively task independent. Is it the better temporal resolution? Perhaps MEG analyses focus on early, bottom up processing, which may be relatively task independent?<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=The+Journal+of+neuroscience+%3A+the+official+journal+of+the+Society+for+Neuroscience&rft_id=info%3Apmid%2F21248130&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Functional+magnetic+resonance+imaging+blood+oxygenation+level-dependent+signal+and+magnetoencephalography+evoked+responses+yield+different+neural+functionality+in+reading.&rft.issn=0270-6474&rft.date=2011&rft.volume=31&rft.issue=3&rft.spage=1048&rft.epage=58&rft.artnum=&rft.au=Vartiainen+J&rft.au=Liljestr%C3%B6m+M&rft.au=Koskinen+M&rft.au=Renvall+H&rft.au=Salmelin+R&rfe_dat=bpr3.included=1;bpr3.tags=Neuroscience%2CCognitive+Neuroscience">Vartiainen J, Liljeström M, Koskinen M, Renvall H, & Salmelin R (2011). Functional magnetic resonance imaging blood oxygenation level-dependent signal and magnetoencephalography evoked responses yield different neural functionality in reading. <span style="font-style: italic;">The Journal of neuroscience : the official journal of the Society for Neuroscience, 31</span> (3), 1048-58 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/21248130" rev="review">21248130</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com2tag:blogger.com,1999:blog-3781583459328436525.post-50314443319679117422011-01-24T14:25:00.000-08:002011-01-24T14:25:47.463-08:00Recycling Neurons for Reading<b>Accesibility</b>: Intermediate-Advanced<br />
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Our brains have evolved to be good at certain things: seeing, hearing, learning language, and interacting with other similar brains, to name a few examples. But say you want it to do something new – look at symbols on a page and map them to language. In other words, you want to teach your brain to read. How would you go about doing this? What parts of the brain would you use?<br />
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Unless you plan on developing a completely new region, it makes sense to repurpose the brain regions you already have -- a process that neuroscientist Stanislas Dehaene refers to as “neuronal recycling.” This raises the question -- what regions are recycled? And do the regions that get co-opted become worse at their original function?<br />
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Dehaene and colleagues explored this question by scanning adults at different levels of literacy: literates, ex-literates (adults who used to be illiterate but learned to read in adulthood), and illiterate adults. They had several interesting findings:<br />
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1. They first looked at whether learning to read changes brain activation when looking at words. Not surprisingly, it does. Reading performance was correlated with increased brain activation in much of the left hemisphere language network, including the visual word form area. And this increased activation appeared to be specific to word-like stimuli.<br />
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2. During reading, ex-literates have more bilateral activation and also recruited more posterior brain regions. This is similar to what we find in children, who also show more spread out activation while reading. This suggests that unskilled readers recruit a wider set of brain regions as they are learning to read. As readers become more skilled, their brains become more efficient and recruit fewer regions<br />
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3. In literate adults, response to checker boards and faces in the visual word form area was lower in the visual word form area compared to non-readers. This suggests that learning to process words may actually be taking resources away from processing other stimuli.<br />
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4. The researchers looked more closely at responses to other faces and houses to see how exactly learning to read competed with other visual functions. They found that activation in the peak voxels for faces and houses did not change with literacy. However, activation in surrounding voxels did decrease.<br />
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5. And here's an interesting result. Since reading is a horizontal process (at least in the languages they were testing), the researchers checked to see if the visual system became more attuned to horizontal stimuli. They found that literacy enhanced response to horizontal but not vertical checker boards in some primary visual areas.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Science+%28New+York%2C+N.Y.%29&rft_id=info%3Apmid%2F21071632&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=How+learning+to+read+changes+the+cortical+networks+for+vision+and+language.&rft.issn=0036-8075&rft.date=2010&rft.volume=330&rft.issue=6009&rft.spage=1359&rft.epage=64&rft.artnum=&rft.au=Dehaene+S&rft.au=Pegado+F&rft.au=Braga+LW&rft.au=Ventura+P&rft.au=Nunes+Filho+G&rft.au=Jobert+A&rft.au=Dehaene-Lambertz+G&rft.au=Kolinsky+R&rft.au=Morais+J&rft.au=Cohen+L&rfe_dat=bpr3.included=1;bpr3.tags=Neuroscience%2CCognitive+Neuroscience">Dehaene S, Pegado F, Braga LW, Ventura P, Nunes Filho G, Jobert A, Dehaene-Lambertz G, Kolinsky R, Morais J, & Cohen L (2010). How learning to read changes the cortical networks for vision and language. <span style="font-style: italic;">Science (New York, N.Y.), 330</span> (6009), 1359-64 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/21071632" rev="review">21071632</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com2tag:blogger.com,1999:blog-3781583459328436525.post-83370339987474617242010-10-07T13:34:00.000-07:002010-10-07T13:34:48.596-07:00White Matter and Reading Ability<b>Accessibility:</b> Intermediate-Advanced <br />
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Hello folks. Things are pretty busy over here and I might be having to review a lot of papers soon, so there's a possibility that entries here will get shorter and a bit more technical. But we'll see.<br />
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Since reading is by nature a multimodal task involving both visual and language regions, it makes sense to look at brain connections in dyslexia. I've written once about white matter in dyslexia, when I blogged <a href="http://wordresearch.liviablackburne.com/2010/03/dyslexia-and-brain-connectivity.html">Bernard Chang’s PNH study</a>. Today I'll cover two other studies that look at white matter and reading.<br />
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As a quick recap, brain tissue is often categorized into gray and white matter. White matter consists mostly of axons, the parts of neurons that send signals to other neurons. Therefore, white matter tracts carry information between brain regions and diffusion tensor imaging is a technique often used to study white matter. You can take several measures with DTI, but one common one is fractional anisotropy, a measure of the directionality of water diffusion. You can think of it as a measure of white matter integrity.<br />
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In one study, James Andrews and colleagues measured white matter integrity in preterm* and term children. They found a correlation between reading skill and fractional anisotropy in the corpus callosum, the large white matter tract that connects the two hemispheres. They also found a trend toward a correlation between reading skill and fractional anisotropy in the left temporal parietal region, a region often associated with reading. I'm surprised by the corpus callosum finding, and wonder its role might be in reading. Is the corpus callosum connecting language regions to their right hemisphere homologues? I also wonder if this is something general to the population, or a difference unique to preterm children. I guess we’ll have to see if this finding comes up in later studies.<br />
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Another DTI study found some more predictable results. Rimrodt and colleagues scanned the brains of children with dyslexia and normal-reading children between the ages of seven and 16 years. They found that children with dyslexia had lower FA in the left inferior frontal gyrus and the left temporoparietal region, both areas previously implicated in reading. Interestingly, they also found that the FA in some posterior areas involved in visual word processing (including the left fusiform) were correlated with speeded word reading.<br />
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*mean gestational age 30.5 weeks<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Developmental+Medicine+%26+Child+Neurology&rft_id=info%3Adoi%2F10.1111%2Fj.1469-8749.2009.03456.x&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Reading+performance+correlates+with+white-matter+properties+in+preterm+and+term+children&rft.issn=00121622&rft.date=2009&rft.volume=52&rft.issue=6&rft.spage=0&rft.epage=0&rft.artnum=http%3A%2F%2Fdoi.wiley.com%2F10.1111%2Fj.1469-8749.2009.03456.x&rft.au=ANDREWS%2C+J.&rft.au=BEN-SHACHAR%2C+M.&rft.au=YEATMAN%2C+J.&rft.au=FLOM%2C+L.&rft.au=LUNA%2C+B.&rft.au=FELDMAN%2C+H.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Neurology">ANDREWS, J., BEN-SHACHAR, M., YEATMAN, J., FLOM, L., LUNA, B., & FELDMAN, H. (2009). Reading performance correlates with white-matter properties in preterm and term children <span style="font-style: italic;">Developmental Medicine & Child Neurology, 52</span> (6) DOI: <a href="http://dx.doi.org/10.1111/j.1469-8749.2009.03456.x" rev="review">10.1111/j.1469-8749.2009.03456.x</a></span><br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cortex&rft_id=info%3Adoi%2F10.1016%2Fj.cortex.2009.07.008&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=White+matter+microstructural+differences+linked+to+left+perisylvian+language+network+in+children+with+dyslexia&rft.issn=00109452&rft.date=2010&rft.volume=46&rft.issue=6&rft.spage=739&rft.epage=749&rft.artnum=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0010945209002226&rft.au=Rimrodt%2C+S.&rft.au=Peterson%2C+D.&rft.au=Denckla%2C+M.&rft.au=Kaufmann%2C+W.&rft.au=Cutting%2C+L.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Neurology">Rimrodt, S., Peterson, D., Denckla, M., Kaufmann, W., & Cutting, L. (2010). White matter microstructural differences linked to left perisylvian language network in children with dyslexia <span style="font-style: italic;">Cortex, 46</span> (6), 739-749 DOI: <a href="http://dx.doi.org/10.1016/j.cortex.2009.07.008" rev="review">10.1016/j.cortex.2009.07.008</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-3079044899867891162010-08-18T10:13:00.000-07:002010-08-18T10:13:53.351-07:00Noise Exclusion Deficits in Dyslexia<b>Accessibility:</b> Intermediate-Advanced <br />
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The human visual system includes two pathways, magnocellular and parvocellular, deriving from two types of <a href="http://en.wikipedia.org/wiki/Retinal_ganglion_cell">retinal ganglion cells</a> that project to different layers of the <a href="http://en.wikipedia.org/wiki/Lateral_geniculate_nucleus">lateral geniculate nucleus</a>. Generally speaking, the magnocelluar pathway is specialized for movement while the parvocellular pathway is specialized for color and detail. Some researchers have found dyslexia to be associated with magnocelluar impairment, although evidence has been mixed.<br />
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A paper from Sperling and colleagues argues that magnocelluar deficits in dyslexica may actually be a deficit in noise exclusion. The authors tested children with and without dyslexia using stimuli that were designed to activate the magnocellular or parvocellular pathways. The magnocellular stimulus was a patch with white bars that alternated rapidly between light and dark. The parvocellular stimulus had thin light and dark bars that did not alternate. <br />
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In addition to the two stimulus types, there was a high noise and low noise condition. In the low noise condition, one of the stimuli appeared to the left or right of the fixation mark. In the high noise condition, noise patches appeared on either side of fixation and the stimulus was overlaid onto one of the noise patches. In both cases, child had to say on which side the stimulus appeared.<br />
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The authors calculated contrast thresholds (the amount of contrast needed between the light and dark bars for accurate detection) for both groups of children. They found no difference in the contrast thresholds for the low noise condition. In the high noise condition, dyslexic children had higher contrast thresholds (more difficulty detecting) for both the magnocellular and parvocellular stimuli. In addition, thresholds in the high noise condition were correlated with language measures.<br />
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These are interesting results. While one study cannot rule out the magnocellular theory of dyslexia, this does open the possibility that many of the results that pointed to a magnocellular deficit were actually cases of noise exclusion deficit. I do remember one paper about motion perception and dyslexia that can't be explained by noise, so I'll see if I can write about that later.<br />
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Another question is, how does noise exclusion lead to dyslexia? It could be that a noise exclusion deficit results in difficulties building phonological categories, which in turn affect reading. The authors also mention that noise exclusion could affect learning in the visual modality by making it harder to extract regularities from different fonts and scripts.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nature+Neuroscience&rft_id=info%3Adoi%2F10.1038%2Fnn1474&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Deficits+in+perceptual+noise+exclusion+in+developmental+dyslexia&rft.issn=1097-6256&rft.date=2005&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=http%3A%2F%2Fwww.nature.com%2Fdoifinder%2F10.1038%2Fnn1474&rft.au=Sperling%2C+A.&rft.au=Lu%2C+Z.&rft.au=Manis%2C+F.&rft.au=Seidenberg%2C+M.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Neurology%2C+Cognitive+Psychology%2C+Developmental+Psychology">Sperling, A., Lu, Z., Manis, F., & Seidenberg, M. (2005). Deficits in perceptual noise exclusion in developmental dyslexia <span style="font-style: italic;">Nature Neuroscience</span> DOI: <a href="http://dx.doi.org/10.1038/nn1474" rev="review">10.1038/nn1474</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com3tag:blogger.com,1999:blog-3781583459328436525.post-82825549742343056682010-08-04T11:33:00.000-07:002010-08-04T11:33:00.060-07:00Sensitivity and Specialization in the Occipitatemporal Region: Differences in Dyslexic Children<b>Accessibility:</b> Advanced/intermediate<br />
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Early research on the role of the occipitotemporal region in reading often focused on characterizing a single region in the mid fusiform, commonly called the visual word form area. Since then, focus has gradually shifted from a single region to the entire length of the occipitotemporal region, looking at how the sensitivity and tuning changes as you move from posterior to anterior regions.<br />
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Van der mark used an approach like this to look at dyslexic and control children aged 9-12 years. Eighteen normal reading and twenty four dyslexic children performed a phonological lexical decision task in the scanner. Children saw words, pseudohomophones (words that sounded like real words but spelled differently, like “taksi”), pseudowords (pronounceable nonwords), and false fonts. The children were asked to decide whether something sounded like a real word. For example, the correct response would be “yes” for words and pseudohomophones and “no” for pseudowords and false fonts.<br />
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The children with dyslexia did worse for pseudohomophones and pseudowords and performed similarly to the controls for words and false fonts.<br />
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The authors report two main findings. First, the control children showed a gradient of print specialization in the occipitotemporal region, with more activation to false fonts in posterior regions and more activation to real letters and anterior regions. The control children did not show this trend. <br />
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Second, control showed more activation for pseudowords and pseudohomophones than words, while children with dyslexia didn't.<br />
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This is a nice study that takes a more nuanced approach to dyslexia brain differences. <a href="http://wordresearch.liviablackburne.com/2010/05/multimodal-investigation-of-reading-in.html">Brem and colleagues</a> also got similar results with the words and false fonts.<br />
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By now there's quite a bit of literature on the specialization of the visual word form area. My own struggle, as I’m also doing this type of research, is the question of what does it all mean? We have all the studies now showing brain differences between control and dyslexic children, but what does it mean to have more or less activation? That the brains of dyslexic children process words differently? I could've told you that before we stared. <br />
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So what would help? Perhaps the next step in dyslexia research, now that we've mapped out the basic differences, is to zoom in as much as we can on the relationships between brain differences and behavioral differences. Perhaps more fine grained behavioral measures would help, or more interventional studies that looked at brain activation before and after training. It may also help to look at functional connectivity and how different brain regions interact. Anyone else have ideas?<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=NeuroImage&rft_id=info%3Apmid%2F19446640&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Children+with+dyslexia+lack+multiple+specializations+along+the+visual+word-form+%28VWF%29+system.&rft.issn=1053-8119&rft.date=2009&rft.volume=47&rft.issue=4&rft.spage=1940&rft.epage=9&rft.artnum=&rft.au=van+der+Mark+S&rft.au=Bucher+K&rft.au=Maurer+U&rft.au=Schulz+E&rft.au=Brem+S&rft.au=Buckelm%C3%BCller+J&rft.au=Kronbichler+M&rft.au=Loenneker+T&rft.au=Klaver+P&rft.au=Martin+E&rft.au=Brandeis+D&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Developmental+Psychology%2C+Cognitive+Psychology%2C+Neurology">van der Mark S, Bucher K, Maurer U, Schulz E, Brem S, Buckelmüller J, Kronbichler M, Loenneker T, Klaver P, Martin E, & Brandeis D (2009). Children with dyslexia lack multiple specializations along the visual word-form (VWF) system. <span style="font-style: italic;">NeuroImage, 47</span> (4), 1940-9 PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/19446640">19446640</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com5tag:blogger.com,1999:blog-3781583459328436525.post-79743728388168890942010-07-12T16:39:00.000-07:002010-07-12T16:39:44.690-07:00Reading induced epilepsy<b>Accessibility:</b> Intermediate<br />
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Just a short entry today. Clinical research is not my specialty, but I ran across a case study today on reading induced epilepsy.<br />
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<i>Seizures began during silent reading with the feeling of no longer being able to understand what she was reading (a- or dyslexia). After looking up from the page, she then continued to see letters and words despite actual disappearance of that image from either visual field (palinopsia). She had a feeling of strangeness. She could then have right hemi-body jerks and secondary generalisation. Seizures usually occurred soon after the onset of reading (less than 10 min). All seizures occurred during silent reading. She had not abandoned reading altogether but had developed a distinct style of reading to try to avoid the onset of seizures, in that she read only for short periods and tended to scan the page diagonally. </i><br />
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</div><div>Not surprisingly, clinical tests revealed that these seizures started in the occipitotemporal region.<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Neurology%2C+Neurosurgery+%26+Psychiatry&rft_id=info%3Adoi%2F10.1136%2Fjnnp.2009.175935&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Reading+epilepsy+from+the+dominant+temporo-occipital+region&rft.issn=0022-3050&rft.date=2009&rft.volume=81&rft.issue=7&rft.spage=710&rft.epage=715&rft.artnum=http%3A%2F%2Fjnnp.bmj.com%2Fcgi%2Fdoi%2F10.1136%2Fjnnp.2009.175935&rft.au=Gavaret%2C+M.&rft.au=Guedj%2C+E.&rft.au=Koessler%2C+L.&rft.au=Trebuchon-Da+Fonseca%2C+A.&rft.au=Aubert%2C+S.&rft.au=Mundler%2C+O.&rft.au=Chauvel%2C+P.&rft.au=Bartolomei%2C+F.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CNeuroscience%2CCognitive+Neuroscience%2C+Neurology"></span><br />
<div><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Neurology%2C+Neurosurgery+%26+Psychiatry&rft_id=info%3Adoi%2F10.1136%2Fjnnp.2009.175935&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Reading+epilepsy+from+the+dominant+temporo-occipital+region&rft.issn=0022-3050&rft.date=2009&rft.volume=81&rft.issue=7&rft.spage=710&rft.epage=715&rft.artnum=http%3A%2F%2Fjnnp.bmj.com%2Fcgi%2Fdoi%2F10.1136%2Fjnnp.2009.175935&rft.au=Gavaret%2C+M.&rft.au=Guedj%2C+E.&rft.au=Koessler%2C+L.&rft.au=Trebuchon-Da+Fonseca%2C+A.&rft.au=Aubert%2C+S.&rft.au=Mundler%2C+O.&rft.au=Chauvel%2C+P.&rft.au=Bartolomei%2C+F.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CNeuroscience%2CCognitive+Neuroscience%2C+Neurology"><br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Neurology%2C+Neurosurgery+%26+Psychiatry&rft_id=info%3Adoi%2F10.1136%2Fjnnp.2009.175935&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Reading+epilepsy+from+the+dominant+temporo-occipital+region&rft.issn=0022-3050&rft.date=2009&rft.volume=81&rft.issue=7&rft.spage=710&rft.epage=715&rft.artnum=http%3A%2F%2Fjnnp.bmj.com%2Fcgi%2Fdoi%2F10.1136%2Fjnnp.2009.175935&rft.au=Gavaret%2C+M.&rft.au=Guedj%2C+E.&rft.au=Koessler%2C+L.&rft.au=Trebuchon-Da+Fonseca%2C+A.&rft.au=Aubert%2C+S.&rft.au=Mundler%2C+O.&rft.au=Chauvel%2C+P.&rft.au=Bartolomei%2C+F.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CNeuroscience%2CCognitive+Neuroscience%2C+Neurology">Gavaret, M., Guedj, E., Koessler, L., Trebuchon-Da Fonseca, A., Aubert, S., Mundler, O., Chauvel, P., & Bartolomei, F. (2009). Reading epilepsy from the dominant temporo-occipital region <span style="font-style: italic;">Journal of Neurology, Neurosurgery & Psychiatry, 81</span> (7), 710-715 DOI: <a href="http://dx.doi.org/10.1136/jnnp.2009.175935" rev="review">10.1136/jnnp.2009.175935</a></span></div></div><div><br />
</div><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-19259926429597431342010-07-08T14:14:00.000-07:002010-07-08T14:14:15.061-07:00fMRI of Letter Processing in Children and Adults<b>Accessibility</b>: Intermediate-Advanced<br />
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How is letter processing different from word processing? Since letters compose words, many reading models have letter processing earlier in the reading stream, but there is still room for more imaging work.<br />
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Turkeltaub and colleagues compared the neural basis of letter processing in children (age 6-11) and adults (age 20-22). The participants were scanned while naming either letters or line drawings out loud. Here are four of their findings.<br />
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1. Adults had more activation than children in visual regions. This appeared to be driven mostly by differences in letter naming*. This suggests that object processing might be more adult-like in kids at this age. <br />
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2. Areas showing a change in letter processing with age were posterior to regions found in other studies to respond to words. Since visual processing moves from back to front, this fits with a model in which letters are processed before words. <br />
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3. The authors found no left hemisphere dominance for letters. This very different words, which are heavily left lateralized. This is also different from <a href="http://wordresearch.liviablackburne.com/2010/05/evidence-suggesting-that-specialized.html">Cantlon 2010</a> which did find letter processing to be left lateralized. I wonder if the results here could be different if the authors had used another method to pick their analysis region**.<br />
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4. The authors also found that no regions activated more for letters than for objects. This is consistent with what I also find in my data. Objects are more visually complex than letters, so it's not surprising that you get more activation for objects. I should note that Cantlon found regions that responded more to letters than objects, but Cantlon only used shoes, which as a set are more uniform than line drawings of different objects.<br />
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*although there is no interaction between objects and letter naming<br />
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**ROI selection based on activation for all tasks.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Annals+of+the+New+York+Academy+of+Sciences&rft_id=info%3Apmid%2F19076386&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Development+of+ventral+stream+representations+for+single+letters.&rft.issn=0077-8923&rft.date=2008&rft.volume=1145&rft.issue=&rft.spage=13&rft.epage=29&rft.artnum=&rft.au=Turkeltaub+PE&rft.au=Flowers+DL&rft.au=Lyon+LG&rft.au=Eden+GF&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Cognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology">Turkeltaub PE, Flowers DL, Lyon LG, & Eden GF (2008). Development of ventral stream representations for single letters. <span style="font-style: italic;">Annals of the New York Academy of Sciences, 1145</span>, 13-29 PMID: <a rev="review" href="http://www.ncbi.nlm.nih.gov/pubmed/19076386">19076386</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-18349984389119178852010-06-23T08:00:00.000-07:002010-06-23T19:42:30.669-07:00A Meta-Analysis of Dyslexia Brain Imaging Studies<b>Accessibility:</b> Advanced<br />
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fMRI experiments, with their small sample sizes, can easily fall victim to variability within the subject pool. This is especially true for patient studies. So it’s nice to step back and look at the big picture once in a while, and see where different studies agree and disagree. <br />
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Richlan and colleagues recently did meta-analysis of dyslexia brain imaging studies. They used an algorithm called Activation Likelihood Estimation (ALE), which models foci of activation as Gaussian probability distributions. (The software is called GingleALE. Ha.)<br />
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Richlan and colleagues picked studies with the following criteria:<br />
1) Uses words, pseudowords or single letters as stimuli<br />
2) Uses reading or reading related task in the scanner, and<br />
3) Group comparisons are done in a standard stereotactic space.<br />
The studies included PET and fMRI studies.<br />
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<b>The take away message is that people with dyslexia underactivate posterior reading regions and may overactivate frontal regions.</b><br />
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The authors found underactivation in regions associated with the phonological reading pathway (reading by sounding out words), including the superior temporal gyrus and inferior parietal lobule. Interestingly, they found no difference in the angular gyrus, a region that has often been reported to be important to reading.<br />
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They also found underactivation the pathway associated with automatic whole word reading, including the left fusiform, inferior temporal and middle temporal regions.<br />
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At a less conservative threshold, the authors found that people with dyslexia overactivated the left inferor frontal region. This is typically interpreted as frontal regions being brought in to compensate for posterior reading regions.<br />
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They did find one posterior region as well that was overactivated in people with dyslexia : the left lingual gyrus, a lower level visual region. Perhaps again, a case of compensation. <br />
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All in all, a nice summary of dyslexia results. Again, I wonder about the relative variablility of dyslexics and controls, and how they affected the results.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Human+Brain+Mapping&rft_id=info%3Adoi%2F10.1002%2Fhbm.20752&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Functional+abnormalities+in+the+dyslexic+brain%3A+A+quantitative+meta-analysis+of+neuroimaging+studies&rft.issn=10659471&rft.date=2009&rft.volume=30&rft.issue=10&rft.spage=3299&rft.epage=3308&rft.artnum=http%3A%2F%2Fdoi.wiley.com%2F10.1002%2Fhbm.20752&rft.au=Richlan%2C+F.&rft.au=Kronbichler%2C+M.&rft.au=Wimmer%2C+H.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Cognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Neurology%2C+Cognitive+Psychology%2C+Developmental+Psychology">Richlan, F., Kronbichler, M., & Wimmer, H. (2009). Functional abnormalities in the dyslexic brain: A quantitative meta-analysis of neuroimaging studies <span style="font-style: italic;">Human Brain Mapping, 30</span> (10), 3299-3308 DOI: <a href="http://dx.doi.org/10.1002/hbm.20752" rev="review">10.1002/hbm.20752</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com4tag:blogger.com,1999:blog-3781583459328436525.post-47084781335008624522010-05-24T13:45:00.000-07:002010-05-24T13:45:55.159-07:00Evidence Suggesting that Specialized Visual Regions Are Formed by Pruning in Early ChildhoodThere are quite a few specialized visual regions in the brain. For example, the fusiform face area (FFA) activates for faces, and the visual word form area (VWFA) in the left fusiform is consistently active for words.<br />
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How do these specialized cortical regions develop? Is it experience dependent? Do regions have a preexisting preference for certain visual features? (For example, perhaps the visual word form region prefers high contrast stimuli with sharp borders). Do these regions form by increasing activation to preferred stimuli, or a decreasing activation to nonpreferred stimuli? Cantlon and colleagues investigated these questions in a recent study.<br />
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They tested prereading five year olds and adults in an fMRI experiment. Participants saw faces, letters, numbers, shoes and scrambled images and pressed a button if a green border appeared around the picture. There were two interesting findings.<br />
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The first concerned the visual word form area. Both adults and children had a specialized brain region in the left fusiform that activated more for letters than objects. However, while <b>adults activated that region more for letters than for numbers, children had equally high activation for letters and numbers.*</b><br />
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These results support a role for both experience and low level visual features in the development of the visual word form area. Note that these children are nonreaders, but they already activate the left fusiform for letters and numbers. So perhaps there’s something hardwired in the left fusiform that prefers symbol-like, high contrast, visual stimuli. But only adults, who have had extensive experience with letters, show differential activation for words and numbers.<br />
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The authors then investigated the relationship between activation level and behavior. They tested children on a face matching task and a letter naming task. Contrary to what you might expect, activation in the fusiform face area did not correlate with face matching skill, and activation in the visual word form area did not correlate with letter naming skill. <br />
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<b>Rather, skill was <i>negatively</i> correlated with activation to the nonpreferred category.</b> Face matching performance was inversely correlated with FFA activation to shoes. And letter naming was inversely correlated with VWFA activation to faces. This suggests that that increased skill in face and letter recognition is associated not with enhancing activation to preferred stimuli, but with pruning back activation to unrelated stimuli. **<br />
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*Methodological note: ROI selection, 10 strongest voxels within a sphere 10mm radius around peaks of All>scrambled. <br />
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**Note that not all nonpreferred stimuli show this inverse correlation. In the face area, there was no correlation between face skill and symbols, and in the VWFA, there is no correlation between letter naming skill and shoe activation. Perhaps these nonpreferred stimuli too far from the preferred stimulus, so no pruning is needed?<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&
amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cerebral+cortex+%28New+York%2C+N.Y.+%3A+1991%29&rft_id=info%3Apmid%2F20457691&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Cortical+Representations+of+Symbols%2C+Objects%2C+and+Faces+Are+Pruned+Back+during+Early+Childhood.&rft.issn=1047-3211&rft.date=2010&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Cantlon+JF&rft.au=Pinel+P&rft.au=Dehaene+S&rft.au=Pelphrey+KA&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology">Cantlon JF, Pinel P, Dehaene S, & Pelphrey KA (2010). Cortical Representations of Symbols, Objects, and Faces Are Pruned Back during Early Childhood. <span style="font-style: italic;">Cerebral cortex (New York, N.Y. : 1991)</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20457691" rev="review">20457691</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com5tag:blogger.com,1999:blog-3781583459328436525.post-48375476986479338252010-05-18T13:59:00.000-07:002010-05-18T13:59:45.043-07:00Multimodal Investigation of Reading in Children: More from Brem and Colleagues<b>Accessibility:</b> Advanced<br />
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Last time we read an article from <a href="http://wordresearch.liviablackburne.com/2010/05/developmental-changes-in-word.html">Brem and colleagues</a> that compared word processing in adolescents (age 15-17) and adults (19-30). In follow-up paper from 2009, Brem expanded the report to include children (9-11).<br />
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If you didn’t read the <a href="http://wordresearch.liviablackburne.com/2010/05/developmental-changes-in-word.html">last post</a>, it’s probably a good idea to do that first. I won’t repeat any of the methodological details or background information here, just gonna make few quick notes on their results.<br />
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The 2006 paper found that adolescents had higher N1 amplitude than adults. Here, Brem reports that children have an even higher N1 amplitude with adolescents, thus suggesting a steady decrease in N1 amplitude from age 9 onwards. <br />
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For all groups, the N1 amplitude was higher for words than symbols. However, the difference between words and symbols declined with age. At first, I found this counterintuitive. I would have expected the opposite, with kids treating words and symbol similarly and the word/symbol difference getting larger as they matured and became better readers. The kids in this study, however, have already been reading for a few years. Perhaps they’re at the stage where they can process the words but are less efficient in doing so, thus resulting in a higher N1 amplitude for words than symbols. <br />
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On the fMRI front, Brem found the same posterior to anterior gradient in the fusiform gyrus, with posterior regions being more responsive to symbols, and anterior regions being more responsive to words. There didn’t seem to be any difference between age groups there. <br />
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Brem also increases that a higher signal in anterior fusiform is correlated with slower reading. <br />
(This is opposite of what was reported in other paper, perhaps I’m misreading the paper.)<br />
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There were some discrepancies between EEG and fMRI results. The N1 ERP component shows clear difference between words and symbols, but the fMRI analysis doesn’t show differences in the occipital temporal region, the calculated source of the N1. The could be due to temporal resolution. The N1 component only lasts about 100 ms. EEG has good enough temporal resolution to pick up on the difference, but fMRI may not.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Human+brain+mapping&rft_id=info%3Apmid%2F19288464&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Tuning+of+the+visual+word+processing+system%3A+distinct+developmental+ERP+and+fMRI+effects.&rft.issn=1065-9471&rft.date=2009&rft.volume=30&rft.issue=6&rft.spage=1833&rft.epage=44&rft.artnum=&rft.au=Brem+S&rft.au=Halder+P&rft.au=Bucher+K&rft.au=Summers+P&rft.au=Martin+E&rft.au=Brandeis+D&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology">Brem S, Halder P, Bucher K, Summers P, Martin E, & Brandeis D (2009). Tuning of the visual word processing system: distinct developmental ERP and fMRI effects. <span style="font-style: italic;">Human brain mapping, 30</span> (6), 1833-44 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/19288464" rev="review">19288464</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-5441630944285610972010-05-14T11:33:00.000-07:002010-05-14T11:33:59.706-07:00Developmental Changes in Word Processing After AdolescenceWhen does brain development for reading stop? We often focus on school aged children, but what about the later teen years? To answer this question, Brem and colleagues tested adolescents (age 15-17) and adults (19-31) in a study using fMRI and EEG.<br />
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Participants were presented with words and symbols strings and asked to detect repeats. It’s an easy task, so it’s not surprising that the two groups had equal reading accuracy and speed. However, there were brain differences. <br />
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Brem focused on two early ERP <a href="http://wordresearch.liviablackburne.com/2010/05/brief-introduction-to-erp-components.html">components</a>. The P1 component, a positive peak at 100 ms, is sensitive to low level stimulus characteristics like luminance and size. Brem found that this component had a higher amplitude for symbol strings and for words in both groups. <br />
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The N1 component occurs later (140-220ms) and is sensitive to higher level factors like stimulus category. Brem found that the later part of the N1 component was more pronounced to words than symbol strings. Source localization on the N1 component found that the early part of the N1 localized to the temporal parietal occipital junction, while the late N1 localized to the left fusiform.<br />
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There were differences between the two groups. <b>Adolescents had higher P1 and N1 amplitudes than adults. The N1 latency also became faster with age for words but not symbol strings. </b><br />
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Brem also used fMRI to look at the spatial organization of the fusiform gyrus*. <b>Posterior fusiform regions responded more to symbol strings than words, while anterior regions responded more to words than symbol strings. </b><br />
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The left fusiform region seems to be related to reading skill. Bigger N1 amplitude was correlated with fewer mistakes in a reading test. Higher fMRI signal in the anterior fusiform was correlated with faster reading.<br />
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It’s interesting that despite similar behavior between groups, brain measures still differ. I do wonder about differences within the adults as well. 19-31 is a pretty big range, so I'd like to see what happens after age 18.<br />
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*Using five regions of interest. 6 mm spheres based on Taleraich coordinates.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=NeuroImage&rft_id=info%3Apmid%2F16257546&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Evidence+for+developmental+changes+in+the+visual+word+processing+network+beyond+adolescence.&rft.issn=1053-8119&rft.date=2006&rft.volume=29&rft.issue=3&rft.spage=822&rft.epage=37&rft.artnum=&rft.au=Brem+S&rft.au=Bucher+K&rft.au=Halder+P&rft.au=Summers+P&rft.au=Dietrich+T&rft.au=Martin+E&rft.au=Brandeis+D&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology">Brem S, Bucher K, Halder P, Summers P, Dietrich T, Martin E, & Brandeis D (2006). Evidence for developmental changes in the visual word processing network beyond adolescence. <span style="font-style: italic;">NeuroImage, 29</span> (3), 822-37 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/16257546" rev="review">16257546</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-36976533302942227082010-05-13T07:17:00.000-07:002010-05-13T07:17:57.004-07:00Brief Introduction to ERP Components<b>Accessibility:</b> Basic<br />
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EEG (electroencephalography) uses scalp electrodes to measure electrical field potentials that result from brain activity. Many EEG studies focus on event related potentials (ERP), patterns of activity that occur in response to a stimulus or cognitive event (Hence, they’re “event related.”).<br />
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Usually, an experimenter averages the brain response over many trials to achieve adequate signal to noise ratio. The end result is a waveform representing the average pattern over trials of a certain type. Peaks and troughs in waveform are known as components. While the naming of components isn’t systematic, they are often named with a letter (P if it’s a peak in the positive direction and N if it’s in the negative direction), and a number that either corresponds to the approximate time of the peak or its order of appearance. Commonly studied components include the <a href="http://en.wikipedia.org/wiki/N400_(neuroscience)">N400</a> and <a href="http://en.wikipedia.org/wiki/P300_(neuroscience)">P300</a>. To learn more about how ERPs are used in research, take a look at entries with the EEG label.<div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-46518970560179687092010-04-29T11:00:00.000-07:002010-05-13T07:21:59.885-07:00Letter-sound Training in Children Causes Brain Specialization for LettersMy research focuses on the left occipitotemporal region. One area in this region, also commonly referred to as the visual word form area, has been shown to activate selectively for letters. Presumably, since reading is too recent a phenomenon to have evolved a specialized brain region, the area develops as a result of experience with words and letters.<br />
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To verify this, some studies have trained adults on a new writing system and scanned them pre and post training to see the effects on the occipitotemporal region. The results have been mixed, and complicated by the fact that adults already know a writing system. It would be simpler and more relevant to look at a training effect in children, and that is what Brem and colleagues did. They trained prereading kindergarteners on letters and found that sensitivity to words developed in the occipitotemporal cortex.<br />
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The children in this experiment trained on a computerized grapheme-phoneme correspondence game that taught them the sounds associated with individual letters. As a control, they also trained on a nonlinguistic number-knowledge game. The participants did eight weeks on each game, with half the group doing the grapheme training first and the other half doing the number training first. This resulted in a nice within-subject control.<br />
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The authors evaluated the children with fMRI and EEG at three time points: 1) Before training, 2) After training with the first game, and 3) after training with the second game. During the fMRI and EEG sessions, the children performed a simple modality judgment task. They were presented with either spoken or written words, false fonts, or unintelligible speech and simply had to say whether the stimulus was in the visual or auditory modality.<br />
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<b>After grapheme-phoneme training, kids showed increased activation to words (as compared to false fonts) in the left occipitotemporal region.</b>* The authors then looked more closely along the length of the fusiform gyrus (located in the occipitotemporal region) and found that there was an increase in activation to words in a posterior region a (MNI coordinates 46,-78, -12)**. This region is posterior to what is usually reported as the adult visual word form area. It would be interesting to see if the region shifts with age.<br />
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The EEG results supported the fMRI findings. <b>One of the <a href="http://wordresearch.liviablackburne.com/2010/05/brief-introduction-to-erp-components.html">ERP components</a>, the N1 peak, was stronger in response to words after training.</b> The source of the N1 localized to the left occipitotemporal region, right cuneus, and posterior cingulate.<br />
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This is a nice study because we can see word expertise development in action, in the age group in which it presumably happens in real life. The authors argue based on previous literature that it’s the visual-phonological mapping that increases specialization in the fusiform, not just visual training. Apparently, previous studies with primarily visual training have not increased activation in the fusiform gyrus, while training adults on phoneme grapheme mapping did. I haven’t looked at those papers recently, but perhaps I’ll investigate them next.<br />
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* The posterior fusiform, right inferior temporal gyrus, and cuenus showed this effect.<br />
**More specifically, the authors did an ROI analysis where they picked 5 ROIS along the length of the fusiform gyrus. The 4th ROI from the front showed this effect. <br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft_id=info%3Apmid%2F20395549&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Brain+sensitivity+to+print+emerges+when+children+learn+letter-speech+sound+correspondences.&rft.issn=0027-8424&rft.date=2010&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Brem+S&rft.au=Bach+S&rft.au=Kucian+K&rft.au=Guttorm+TK&rft.au=Martin+E&rft.au=Lyytinen+H&rft.au=Brandeis+D&rft.au=Richardson+U&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology">Brem S, Bach S, Kucian K, Guttorm TK, Martin E, Lyytinen H, Brandeis D, & Richardson U (2010). Brain sensitivity to print emerges when children learn letter-speech sound correspondences. <span style="font-style: italic;">Proceedings of the National Academy of Sciences of the United States of America</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20395549" rev="review">20395549</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-10306051776234085482010-04-21T14:41:00.000-07:002010-04-21T14:41:34.232-07:00Posterior Brain Differences in Children with Dyslexia<b>Accessibility: </b>Intermediate-Advanced <br />
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I realized after the last post that we haven’t actually spent much time discussing brain differences between dyslexic and nonimpaired readers. So today, I’m covering an earlier experiment by the Shaywitz’s.<br />
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In a 2002 paper, Shaywitz and colleagues reported an experiment with 144 children aged 7-17, half dyslexic and half nonimpaired. The children performed several tasks in the scanner, but the paper focuses on two: nonword rhyme (NWR) (Does [PEAT] rhyme with [LEAT]?) and semantic categorization (CAT)(Are [CORN] and [RICE] in the same category?). A line match task was used as a <a href="http://wordresearch.liviablackburne.com/2010/03/dyslexic-vs-nonimpaired-readers.html">baseline</a>.<br />
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During fMRI, the nonimpaired readers showed more activation than dyslexic readers in a large number of left and right hemisphere brain regions.* <br />
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The authors also looked at brain regions where reading skill correlated with activation. The left occipitotemporal (OT) region correlated with skill in both tasks, while bilateral parietotemporal regions showed a correlation with skill in the categorization task only. <br />
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This isn’t the first time activation in the OT has been linked to reading skill. <a href="http://wordresearch.liviablackburne.com/2010/01/dyslexia-brain-differences-show-up.html">Specht 2009</a> found that OT activation during a categorization task correlates with reading score even before formal reading instruction. <a href="http://wordresearch.liviablackburne.com/2010/04/phonological-training-changes-brain.html">Shaywitz 2004</a> found activation increases in the left OT region a year after completion of a phonological intervention. Also, this paper reported negative correlation between reading skill and activation in right OT gyrus during a categorization task, a correlation that was also reported in <a href="http://wordresearch.liviablackburne.com/2010/04/development-of-visual-word-recognition.html">Turkeltaub 2003</a>**. <br />
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Finally, the authors looked at brain regions where activation correlates with age and found striking differences between dyslexic and nonimpaired readers. Dyslexic readers had many regions that increased in activation with age***. In normal readers, there were few correlations with increasing age, and age correlated negatively with superior frontal and middle frontal regions. One possible explanation is that dyslexics learn to compensate with other brain regions as they grow older. The normal readers, on the other hand, get more efficient in their reading.****<br />
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The age result also highlights the variability in the sample. Children with dyslexia change greatly in brain activation as they grow older. You can imagine the variability that this would produce in an random experimental sample of 15 kids. I wonder if there’s been much work on relative variability in dyslexic children vs. nonimpaired children.<br />
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*NWR in left hemisphere sites (inferior frontal gyrus, superior temporal sulcus, superior temporal gyrus, middle temporal gyrus, middle occipital gyrus) and right hemisphere (Inferior frontal, superior temporal sulcus, middle temporal gyrus, medial orbital.) CAT in left (angular gyrus, middle temporal gyrus, middle occipital) and in right (middle temporal gyrus, middle occipital)<br />
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**Turkeltaub didn’t find a positive correlation in left OT, and also used a lower level task (tall letter detection.<br />
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*** IN NWR in DYS, increased age correlated with activation in bilateral IFG, basal ganglia, posterior cingulate, cuneus, middle occipital gyri and left STG. <br />
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****Correlations with age in dyslexics and normal readers are also explored in <a href="http://wordresearch.liviablackburne.com/2010/03/dyslexic-vs-nonimpaired-readers.html">Shaywitz 2007</a>. In that paper, they do report regions in nonimpaired readers that increase activation with age. It might be the same dataset, but I’m not sure. <br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Biological+Psychiatry&rft_id=info%3Adoi%2F10.1016%2FS0006-3223%2802%2901365-3&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Disruption+of+posterior+brain+systems+for+reading+in+children+with+developmental+dyslexia&rft.issn=00063223&rft.date=2002&rft.volume=52&rft.issue=2&rft.spage=101&rft.epage=110&rft.artnum=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0006322302013653&rft.au=Shaywitz%2C+B.&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Developmental+Psychology%2C+Cognitive+Psychology%2C+Neurology">Shaywitz, B. (2002). Disruption of posterior brain systems for reading in children with developmental dyslexia <span style="font-style: italic;">Biological Psychiatry, 52</span> (2), 101-110 DOI: <a href="http://dx.doi.org/10.1016/S0006-3223%2802%2901365-3" rev="review">10.1016/S0006-3223(02)01365-3</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com5tag:blogger.com,1999:blog-3781583459328436525.post-28412070810237957952010-04-15T08:13:00.000-07:002010-04-15T08:13:18.427-07:00Phonological Training Changes Brain Activation in Dyslexic Children<i>Note: Online Universities has included me in their list of top <a href="http://www.onlineuniversities.com/blog/2010/04/50-best-female-science-bloggers/">50 female science bloggers</a>. It’s not actually for this blog, but for my <a href="http://blog.liviablackburne.com/">Brain Science and Creative Writing</a> blog. Anyways, check out the list if you get a chance. There are lot of interesting bloggers.</i><br />
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<b>Accessibility: </b>Intermediate-Advanced<br />
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We’ve looked at the neuroscience of dyslexia and how the dyslexic brain processes words. Our ultimate goal, however, is treatment. Therefore, we’d like to see whether reading interventions cause brain changes in reading-impaired children. In a 2004 paper in Biological Psychiatry, Shaywitz and colleagues investigated this question.<br />
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The study focused on kids aged 6-9, divided into three groups. The experimental group consisted of reading-disabled students who went through an eight month experimental intervention that focused on phonology: letter-sound associations, combining sounds, etc.. Another group of reading-impaired children were put in community intervention control group that participated in a variety of reading interventions, including remedial reading and tutoring. However, there was no specific focus on phonology. A third group, community control, consisted of normal reading children.*<br />
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All groups improved in their reading measures after 8 months (not surprising, since they continued to attend school). The experimental group showed more improvement than the community intervention group in one reading measure.<br />
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Shaywitz and colleagues were interested in brain differences before and after intervention. They scanned the kids pre/post intervention in a letter identification task.** Their main analysis was a second order comparion. They first determined the pre/post intervention changes within each group. Then they compared the changes between groups. <br />
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Compared to the community intervention control, both the experimental intervention and normal-reading control group showed a greater increase in left inferior frontal gyrus (often involved in phonological processing) activation. The experimental intervention group showed more increase in left middle temporal gyrus activation compared to the community intervention group.<br />
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In addition to comparing pre/post intervention differences between groups, Shaywitz also scanned the experimental group a year after finishing the intervention. The group showed continued increases in several left hemisphere areas, including left inferior frontal, superior temporal, and left occipitotemporal regions***. Also, they showed a decrease in right MTG and right caudate activation. This falls in line with the increase in left lateralization we saw in <a href="http://wordresearch.liviablackburne.com/2010/04/development-of-visual-word-recognition.html">Turkeltaub 2003</a>. <br />
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What’s the take home message? This study shows us that phonological intervention results in measurable brain changes in the left inferior frontal gyrus, a phonological region. This is encouraging. However, how does this actually impact reading performance? The experimental group only performed significantly better than the community intervention group in one reading measure, although it looks like they performed slightly better (but not statistically significant) in other measures. So there is a hint that phonological interventions might be more valuable than other interventions, but we’d have to get more data on this.<br />
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The study also shows that brain regions in the experimental group continue to develop during the year after the intervention. When did these changes start – during intervention or afterwards? It's hard to tell because they don't report the changes in the experimental intervention group right after intervention. They only report on the difference in changes between groups. <br />
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Also are these changes jumpstarted by the intervention, or would they have occurred anyway? Unfortunately, we can’t answer that question either. While the authors had hoped to also scan the two other groups a year afterwards, they were unable to.<br />
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Anyways, it's kinda cool to see brain differences as a result of training. It will be interesting to see in future studies what is going on in more detail.<br />
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*Children from the EI group were from Syracuse, NY, while the other two groups were recruited from New Haven.<br />
**The kids heard a letter name and had to choose the correct letter from two options. This task was compared against baseline of hearing tone and specifying position of asterisk.<br />
***LIFG, STG, left OT, left lingual, and left inferior occipital<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Biological+psychiatry&rft_id=info%3Apmid%2F15110736&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Development+of+left+occipitotemporal+systems+for+skilled+reading+in+children+after+a+phonologically-+based+intervention.&rft.issn=0006-3223&rft.date=2004&rft.volume=55&rft.issue=9&rft.spage=926&rft.epage=33&rft.artnum=&rft.au=Shaywitz+BA&rft.au=Shaywitz+SE&rft.au=Blachman+BA&rft.au=Pugh+KR&rft.au=Fulbright+RK&rft.au=Skudlarski+P&rft.au=Mencl+WE&rft.au=Constable+RT&rft.au=Holahan+JM&rft.au=Marchione+KE&rft.au=Fletcher+JM&rft.au=Lyon+GR&rft.au=Gore+JC&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Neurology%2C+Cognitive+Psychology%2C+Developmental+Psychology">Shaywitz BA, Shaywitz SE, Blachman BA, Pugh KR, Fulbright RK, Skudlarski P, Mencl WE, Constable RT, Holahan JM, Marchione KE, Fletcher JM, Lyon GR, & Gore JC (2004). Development of left occipitotemporal systems for skilled reading in children after a phonologically- based intervention. <span style="font-style: italic;">Biological psychiatry, 55</span> (9), 926-33 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/15110736" rev="review">15110736</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com1tag:blogger.com,1999:blog-3781583459328436525.post-51886515725764077072010-04-06T15:39:00.000-07:002010-04-06T16:52:34.769-07:00The Development of Visual Word Recognition<b>Accessibility: </b>Intermediate-Advanced <br />
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We’ve looked at brain regions and development during word related tasks (<a href="http://wordresearch.liviablackburne.com/2010/03/brain-change-patterns-in-developing.html">word</a> <a href="http://wordresearch.liviablackburne.com/2010/03/comparing-child-and-adult-brains-how-to.html">generation</a>, <a href="http://wordresearch.liviablackburne.com/2010/03/development-of-modality-tuning-during.html">reading and repeating</a>), but we haven’t yet looked at a straight up study of word recognition and development. <br />
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What’s the best task to use to study visual word recognition? You can have people read out loud, but that involves processes like speech generation. Likewise, reading sentences or paragraphs requires the reader to process meaning and grammar in addition to the words on the page.<br />
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One segment of the field has gravitated towards tasks of single word processing that don’t require reading at all. In this particular study, Turkeltaub and colleagues use a tall letter detection task. The subjects press a button if the word has a tall letter (like d or l). As a control condition, subjects perform the same task on false fonts. Even though you can do this task without reading the words, the assumption is that reading, being highly automatic, will occur anyways. This approach, focusing on the automatic, bottom up process, allows for a more tightly controlled study. However, it also limits the findings to that very thin slice of the reading process.<br />
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Turkeltaub and colleagues tested forty one subjects ranging from 8 to 20 years old. In the whole group, the words > symbols contrast gives activation in the left posterior temporal, left inferior frontal, and right inferior parietal regions.<br />
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The authors also looked at correlations between activation and reading ability. The trend here seems to be increasing lateralization (more reliance on left hemisphere regions and less reliance on right hemisphere regions), with reading skill.* Interesting. I wonder how this relates to lateralization of spoken language.<br />
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Finally, the authors looked for regions that correlated with other behavioral measures, including phonetic working memory (left intraparietal sulcus and left and right middle frontal gyri), phonological awareness (left hemisphere network, incluing posterior STS and ventral inferior frontal), and phonological naming (bilateral network, including right posterior superior temporal, right middle tempral, and left ventral inferior frontal.) Surprisingly (to me at least) there is almost no overlap between the regions for the three measures. This could either mean that these measures involve very different cognitive and neural processes, or that the automatic task used in this experiment was not suited for accurately tapping into these abilities.<br />
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*Reading ability correlated positively with activation left hemisphere frontal and temporal cortical areas, and negatively with right hemisphere posterior regions. There was no correlation in the left fusiform (visual word form area), but there is a negative correlation in right posterior fusiform. <br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nature+Neuroscience&rft_id=info%3Adoi%2F10.1038%2Fnn1065&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Development+of+neural+mechanisms+for+reading&rft.issn=10976256&rft.date=2003&rft.volume=6&rft.issue=7&rft.spage=767&rft.epage=773&rft.artnum=http%3A%2F%2Fwww.nature.com%2Fdoifinder%2F10.1038%2Fnn1065&rft.au=Turkeltaub%2C+P.&rft.au=Gareau%2C+L.&rft.au=Flowers%2C+D.&rft.au=Zeffiro%2C+T.&rft.au=Eden%2C+G.&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology">Turkeltaub, P., Gareau, L., Flowers, D., Zeffiro, T., & Eden, G. (2003). Development of neural mechanisms for reading <span style="font-style: italic;">Nature Neuroscience, 6</span> (7), 767-773 DOI: <a href="http://dx.doi.org/10.1038/nn1065" rev="review">10.1038/nn1065</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com3tag:blogger.com,1999:blog-3781583459328436525.post-40491109071664279292010-04-01T16:02:00.000-07:002010-04-01T16:02:24.505-07:00Rats Who Can't Read Good: A Rodent Model for Dyslexia<b>Accesibility: </b>Intermediate <br />
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Dyslexic rats? Really? Well, these rats can’t read, but they’re still used as an animal model for dyslexia.<br />
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First, some background. The underlying cause of dyslexia is still under debate, but it’s generally accepted that it involves deficits in auditory and phonological (language sounds) processing, with a possibility of visual deficits as well. Post mortem studies of dyslexic human brains have turned up brain anomalies, including cortical ectopias (nests of neurons in the wrong layer in the cortex) and focal microgyri (micro folding). Researchers have also found abnormalities in the thalamus and cerebellum.<br />
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Dyslexia rat models are created by inducing these same abnormalities, usually focal microgyria and molecular layer ectopias, in rats. Interestingly, some of these rats develop deficits in rapid auditory processing, which is important for phonological processing in humans. Introducing microgyria also causes thalamic changes in male rats, similar to dyslexic thalami in humans. The thalamic changes are also associated with auditory perceptual deficits in the males. <br />
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Another interesting observation: boys are more at risk than girls for dyslexia, and the same trend occurs in rats. Young male rats have a higher risk for developing rapid auditory processing deficits from induced cortical malformations. There seems to be something about the male brain that increases risk for language related disorders.<br />
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Hmm, anyone want to start Hooked on Phonics for rodents?<br />
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[And kudos to anyone who got the <a href="http://www.amazon.com/gp/product/B00003CXPJ?ie=UTF8&tag=livblaabrasci-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=B00003CXPJ">Zoolander</a> reference in the title]<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Nature+neuroscience&rft_id=info%3Apmid%2F17001339&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=From+genes+to+behavior+in+developmental+dyslexia.&rft.issn=1097-6256&rft.date=2006&rft.volume=9&rft.issue=10&rft.spage=1213&rft.epage=7&rft.artnum=&rft.au=Galaburda+AM&rft.au=LoTurco+J&rft.au=Ramus+F&rft.au=Fitch+RH&rft.au=Rosen+GD&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Behavioral+Neuroscience%2C+Cognitive+Psychology%2C+Neurology">Galaburda AM, LoTurco J, Ramus F, Fitch RH, & Rosen GD (2006). From genes to behavior in developmental dyslexia. <span style="font-style: italic;">Nature neuroscience, 9</span> (10), 1213-7 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/17001339" rev="review">17001339</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-86626843162794525082010-03-31T13:33:00.000-07:002010-03-31T13:33:20.144-07:00Dyslexic vs. Nonimpaired Readers: Differences in Brain Development<b>Accessibility:</b>Intermediate/Advanced<br />
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Studies comparing normal reading and dyslexic children often take a snapshot approach, comparing brain function at specific ages. However, these studies don’t tell us how these differences fit into the developmental picture. Are dyslexics following the same developmental course as normal readers, just at a different rate? Or do dyslexic brains develop in a completely different way? <br />
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Instead of comparing activation at each age, Shaywitz and colleagues compared the way the two groups changed throughout development. They conducted a massive imaging study involving 113 dyslexic children (ages 7-18) and 119 nonimpaired children aged (7-17). The participants did two tasks: a line match task (Do ///\ and //// match?) and a nonword rhyme task (Do leat and kete rhyme?) <br />
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In all the imaging results, the authors looked at the rhyming> line match contrast*. (For an explanation of contrasts and subtraction logic in fMRI, see <a href="http://wordresearch.liviablackburne.com/2010/03/fmri-subraction-analysis-and-why-it.html">this post</a>). Both groups had brain regions that changed in activation with age. However, the regions were different. In normal readers, the left anterior lateral occipital region (close to the visual word form area) became more active with age. In dyslexics, however, a more posterior region of the left occipitotemporal cortex became more active. <br />
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Developmental patterns in the front of the brain were also different. Normal readers showed an activation decrease in the right middle frontal/superior frontal region while dyslexic readers showed a decrease in the right superior frontal region.<br />
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The authors also looked at asymmetry. In normal readers (but not dyslexic), activity in the anterior lateral occipitotemporal region became increasingly asymmetric with age.<br />
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From these results, it appears that dyslexic readers aren’t just delayed versions of normal readers. Different regions are developing in each group, and the two groups are learning to use different brain regions to perform the same task. What does this mean? Different strategies? Compensatory processing? Hrmm…<br />
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Addendum: Careful readers might notice that there are some differences between these results and other papers I’ve discussed. <a href="http://wordresearch.liviablackburne.com/2010/03/brain-change-patterns-in-developing.html">Brown 2004</a> found an increase in left inferior frontal regions with age, but this paper only found it in dyslexic readers. Brown also found decreases in left extrastriate regions, while this group found increases. This could be due to the different tasks or subject variation.<br />
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*I’d be curious to see the correlations with age and task activations separately rather than just the rhyme>match contrast. It’d be interesting to see whether these correlations are due to changes in rhyming activation, line match, or both.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Annals+of+neurology&rft_id=info%3Apmid%2F17444510&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Age-related+changes+in+reading+systems+of+dyslexic+children.&rft.issn=0364-5134&rft.date=2007&rft.volume=61&rft.issue=4&rft.spage=363&rft.epage=70&rft.artnum=&rft.au=Shaywitz+BA&rft.au=Skudlarski+P&rft.au=Holahan+JM&rft.au=Marchione+KE&rft.au=Constable+RT&rft.au=Fulbright+RK&rft.au=Zelterman+D&rft.au=Lacadie+C&rft.au=Shaywitz+SE&rfe_dat=bpr3.included=1;bpr3.tags=Clinical+Research%2CPsychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology%2C+Developmental+Psychology%2C+Neurology">Shaywitz BA, Skudlarski P, Holahan JM, Marchione KE, Constable RT, Fulbright RK, Zelterman D, Lacadie C, & Shaywitz SE (2007). Age-related changes in reading systems of dyslexic children. <span style="font-style: italic;">Annals of neurology, 61</span> (4), 363-70 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/17444510" rev="review">17444510</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com2tag:blogger.com,1999:blog-3781583459328436525.post-73260790295249455852010-03-30T13:58:00.000-07:002010-03-30T14:00:20.625-07:00fMRI Subraction Analysis and Why it Matters<b>Accessibility: </b>Basic <br />
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Let’s say you wanted to do an experiment about color processing. We could do the following: <br />
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1. Roll someone into the scanner. <br />
2. Show them two colors<br />
3. Have them press the button corresponding to the color they prefer. <br />
4. Look at the resulting activations, and voila, we have the “color preference area.”<br />
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But it’s not that simple. The brain is very active, even when supposedly at rest. While performing the task described, the subject is also breathing, processing ambient noise, thinking about grocery shopping, as well as who knows what else. How do you tell what activation is due to the color judgment, and what is due to other processes?<br />
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The traditional fMRI solution is to compare activation with a baseline condition. For our example experiment, we may want a comparison condition where the subject sees the same images, but presses a random button rather than picking a color. We then take the activation from this comparison condition and subtract it form the condition we’re interested in. The assumption (and it’s an assumption, meaning that it may not always be true) is that we’re subtracting out irrelevant brain activation– for example, brain activation due to seeing colors, pressing buttons, being inside a scanner, etc.<br />
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This is important to keep in mind when evaluating fMRI results. If someone tells you that brain region X is active during a certain task, you always want to ask what the comparison condition is. If region X is active during task Y, but the comparison condition is super simple (say just laying there in the scanner, for example), that’s not very impressive – lots of other regions will be active in that comparison, and it may not be simply due to that task. <br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com0tag:blogger.com,1999:blog-3781583459328436525.post-19833436109667969372010-03-22T10:12:00.000-07:002010-03-22T10:15:03.487-07:00Development of Modality Tuning During Reading and Repetition<b>Accessibility Level:</b> Intermediate/Advanced <br />
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Today we’re again looking at the theme of increasing specialization in the brain over development. Rather than specialization in terms of spatial extent, as touched on in <a href="http://wordresearch.liviablackburne.com/2010/03/brain-change-patterns-in-developing.html">Brown 2004, Cerebral Cortex</a>, this paper’s finding suggests specialization in processing of sensory modalities.<br />
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Church and colleagues tested children (age 7-10) and adults (18-35) in a word generation task. During the experiment they read words off a screen and repeated words presented aurally. Like the <a href="http://wordresearch.liviablackburne.com/2010/03/brain-change-patterns-in-developing.html">two</a> <a href="http://wordresearch.liviablackburne.com/2010/03/comparing-child-and-adult-brains-how-to.html">papers </a>previously discussed here by this group, the authors matched for behavior between children and adults.<br />
They authors report several findings. <br />
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1. First, <b>most brain regions did not change in activation over time</b>. In well known language areas like the inferior frontal gyrus and superior temporal gyrus, the authors found no difference between children and adults. Also, they found <b>no differences in lateralization</b> (how much one side of the brain was favored over another) between children and adults.<br />
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2. <b>The regions that differed between the two groups were mainly extrastriate visual regions, and all regions with differences had greater activation for children than adults</b>. Unlike the Brown 2005 paper, where some frontal regions were found to have greater activation in adults, this paper found no such regions. This could be due to the different task (word generation vs. reading/repeating), or variation in the participant pools of the two the studies.<br />
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3. In several visual regions, including a cluster very close to the visual word form area, adults had more activation to the visual presentation than to auditory presentation, while children had similar activation to the two modalities. This suggests that these ar<b>eas might be more specialized for the visual modality in adults</b>. In other words, the region gets “tuned” to the visual modality as the children mature (However, the interaction between modality and age was not statistically significant). The authors propose several possible mechanisms responsible for this modality tuning difference. Perhaps the kids are using a different strategy, visualizing more during the auditory task. Or perhaps their brains are just organized differently.<br />
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Together with the Brown 2004 paper, this paper presents an interesting story about increasing specialization and efficiency in the maturing brain, in which the immature brain starts out with relatively nonspecialized brain regions and recruits more brain regions to accomplish the tasks at hand. Then, maturation and expertise result in more specialization, finer tuning, and fewer recruited regions.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cerebral+cortex+%28New+York%2C+N.Y.+%3A+1991%29&rft_id=info%3Apmid%2F18245043&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=A+developmental+fMRI+study+of+reading+and+repetition+reveals+changes+in+phonological+and+visual+mechanisms+over+age.&rft.issn=1047-3211&rft.date=2008&rft.volume=18&rft.issue=9&rft.spage=2054&rft.epage=65&rft.artnum=&rft.au=Church+JA&rft.au=Coalson+RS&rft.au=Lugar+HM&rft.au=Petersen+SE&rft.au=Schlaggar+BL&rfe_dat=bpr3.included=1;bpr3.tags=Psychology%2CNeuroscience%2CCognitive+Neuroscience%2C+Developmental+Neuroscience%2C+Cognitive+Psychology">Church JA, Coalson RS, Lugar HM, Petersen SE, & Schlaggar BL (2008). A developmental fMRI study of reading and repetition reveals changes in phonological and visual mechanisms over age. <span style="font-style: italic;">Cerebral cortex (New York, N.Y. : 1991), 18</span> (9), 2054-65 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/18245043" rev="review">18245043</a></span><br />
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</span><div class="blogger-post-footer">What is it that transforms a page full of words into an experience that moves us and leaves us changed? <a href="http://www.amazon.com/review/R3IHPMBIU0ZI66/?_encoding=UTF8&ASIN=B004GKMZ30#wasThisHelpful"> K. Okada </a> <a href="http://blog.liviablackburne.com/2010/12/from-words-to-brain-call-for-reviewers.html"> From Words to Brain </a></div>Livia Blackburnehttp://www.blogger.com/profile/15805379309049803903noreply@blogger.com2