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Summaries of recent research on reading and word recognition.
Livia
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- January 28, 2010
- 07:51 PM
- 751 views
Dyslexia Brain Differences Show Up Before Formal Reading Instruction
by Livia in Reading and Word Recognition Research
Last time, we talked about early behavioral differences between prereading children that predicted future reading impairment. Today, we’re continuing on the theme of early predictive differences, this time in the brain.
The question of how early brain differences arise is a worthwhile one. We want to know whether the dyslexic brain is tackling reading differently from the very beginning or if these brain differences arise after some reading experience, perhaps reflecting compensatory strategies that the children may have developed.
Specht and colleagues (Scandinavian Journal of Psychology 2008) conducted a brain imaging study on Norwegian children (a good population to study because reading instruction starts in second grade in Norway). The basic goal of their experiment was to scan 6 year olds (before they learned to read) and see if they process words differently depending on their risk for dyslexia. Unlike the Lervag study, this study was not longitudinal. Specht and colleagues determined which kids were at risk for dyslexia using a risk index that took into account factors like heredity, language development, and other factors.
Kids looked at four kinds of stimuli during an fmri scan: pictures, logos, regular words and irregular words while performing a categorization task (“Is this something you can play with?” and similar questions). I won’t spend too much time comparing between conditions because I’m not clear on what characteristics were controlled for between the stimulus types.
There were differences between the at-risk and normal reading group in all conditions. There were several interesting findings. First, risk index score correlated with increased activation when looking at words in the angular gyrus, an area that has been reported to be involved in language/phonological processing.
Our old friend, the visual word form area, also shows up. At a more liberal statistical threshold ( p... Read more »
Specht K, Hugdahl K, Ofte S, Nygård M, Bjørnerud A, Plante E, & Helland T. (2009) Brain activation on pre-reading tasks reveals at-risk status for dyslexia in 6-year-old children. Scandinavian journal of psychology, 50(1), 79-91. PMID: 18826418
- February 11, 2010
- 10:58 AM
- 746 views
Is Dyslexia a Visual or Phonological Deficit?
by Livia in Reading and Word Recognition Research
It's interesting how the public's impression of dyslexia differs from the impressions of researchers in the field. I recently read an article by Vidyasagar and Pammer arguing that dyslexia is a visual deficit. To the general public, this claim seems obvious because most people believe that people with dyslexia see things backwards.
Many dyslexia researchers, however, will find this claim
... Read more »
Vidyasagar, T., & Pammer, K. (2010) Dyslexia: a deficit in visuo-spatial attention, not in phonological processing. Trends in Cognitive Sciences, 14(2), 57-63. DOI: 10.1016/j.tics.2009.12.003
- May 14, 2010
- 03:30 PM
- 745 views
Developmental Changes in Word Processing After Adolescence
by Livia in Reading and Word Recognition Research
When 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...
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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. NeuroImage, 29(3), 822-37. PMID: 16257546
- March 31, 2010
- 05:13 PM
- 731 views
Dyslexic vs. Nonimpaired Readers: Differences in Brain Development
by Livia in Reading and Word Recognition Research
Accessibility:Intermediate/Advanced
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
... Read more »
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. Annals of neurology, 61(4), 363-70. PMID: 17444510
- March 8, 2010
- 10:42 PM
- 711 views
Brain Change Patterns in Developing Children
by Livia in Reading and Word Recognition Research
Accessibility Level: Intermediate-Advanced
What changes in the brain as children mature? Are there patterns in the way the changes occur? Do some regions mature more quickly than others?
Last time, we talked about a paper by Schlaggar et al that examined brain differences between children and adults during a word generation task. A study published in Cerebral Cortex by Brown and colleagues
... Read more »
Brown, T. (2004) Developmental Changes in Human Cerebral Functional Organization for Word Generation. Cerebral Cortex, 15(3), 275-290. DOI: 10.1093/cercor/bhh129
- April 29, 2010
- 08:32 PM
- 668 views
Letter-sound Training in Children Causes Brain Specialization for Letters
by Livia in Reading and Word Recognition Research
My 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...
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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. Proceedings of the National Academy of Sciences of the United States of America. PMID: 20395549
- March 3, 2010
- 06:24 PM
- 654 views
Comparing Child and Adult Brains: How to Account for Performance Differences?
by Livia in Reading and Word Recognition Research
In an ideal world, we’d be able to study maturational brain changes by scanning a group of adults, a group of children, and comparing the brain images. Unfortunately, there are complications.
One complication is that these studies usually require doing some kind of task in the scanner, and children usually have lower accuracy and longer reaction times on this task. These differences,
... Read more »
Schlaggar BL, Brown TT, Lugar HM, Visscher KM, Miezin FM, & Petersen SE. (2002) Functional neuroanatomical differences between adults and school-age children in the processing of single words. Science (New York, N.Y.), 296(5572), 1476-9. PMID: 12029136
Casey, B. (2002) NEUROSCIENCE: Windows into the Human Brain. Science, 296(5572), 1408-1409. DOI: 10.1126/science.1072684
- April 8, 2011
- 11:10 AM
- 646 views
The N1 Component in Prereading Children
by Livia in Reading and Word Recognition Research
Accessibility: Intermediate-Advanced
Just to recap from the last article, 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?
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).
They found several things:
1. Adults again had the same N170 (called N1 in this paper), which was stronger for words than symbols.
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.
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.
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.
Maurer U, Brem S, Bucher K, & Brandeis D (2005). Emerging neurophysiological specialization for letter strings. Journal of cognitive neuroscience, 17 (10), 1532-52 PMID: 16269095
What is it that transforms a page full of words into an experience that moves us and leaves us changed? K. Okada From Words to Brain
... Read more »
Maurer U, Brem S, Bucher K, & Brandeis D. (2005) Emerging neurophysiological specialization for letter strings. Journal of cognitive neuroscience, 17(10), 1532-52. PMID: 16269095
- April 15, 2010
- 12:07 PM
- 639 views
Phonological Training Changes Brain Activation in Dyslexic Children
by Livia in Reading and Word Recognition Research
Note: Online Universities has included me in their list of top 50 female science bloggers. It’s not actually for this blog, but for my Brain Science and Creative Writing blog. Anyways, check out the list if you get a chance. There are lot of interesting bloggers.
Accessibility: Intermediate-Advanced
We’ve looked at the neuroscience of dyslexia and how the dyslexic brain processes words.
... Read more »
Shaywitz BA, Shaywitz SE, Blachman BA, Pugh KR, Fulbright RK, Skudlarski P, Mencl WE, Constable RT, Holahan JM, Marchione KE.... (2004) Development of left occipitotemporal systems for skilled reading in children after a phonologically- based intervention. Biological psychiatry, 55(9), 926-33. PMID: 15110736
- March 15, 2010
- 01:04 PM
- 629 views
Dyslexia and Brain Connectivity: Insights from Periventricular Nodular Heterotopia
by Livia in Reading and Word Recognition Research
Accessibility Level: Intermediate
One theory of dyslexia is that it stems from abnormal brain connectivity -- that faulty connections between different language areas result in reading difficulty. Now, some evidence from another condition offers some support for this theory.
Periventricular nodular heterotopia (PNH) is a neurological condition in which neurons don’t migrate to the correct
... Read more »
Chang, B., Katzir, T., Liu, T., Corriveau, K., Barzillai, M., Apse, K., Bodell, A., Hackney, D., Alsop, D., Wong, S.... (2007) A structural basis for reading fluency: White matter defects in a genetic brain malformation. Neurology, 69(23), 2146-2154. DOI: 10.1212/01.wnl.0000286365.41070.54
- April 7, 2011
- 03:13 PM
- 609 views
Introduction to the N170 Response to Words
by Livia in Reading and Word Recognition Research
Accessibility: Intermediate-Advanced
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.
For this post, we'll start with the basics. The N170 is an ERP component 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).
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.
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.
*the task was to detect repetitions
Maurer U, Brandeis D, & McCandliss BD (2005). Fast, visual specialization for reading in English revealed by the topography of the N170 ERP response. Behavioral and brain functions : BBF, 1 PMID: 16091138
What is it that transforms a page full of words into an experience that moves us and leaves us changed? K. Okada From Words to Brain
... Read more »
Maurer U, Brandeis D, & McCandliss BD. (2005) Fast, visual specialization for reading in English revealed by the topography of the N170 ERP response. Behavioral and brain functions : BBF, 13. PMID: 16091138
- July 8, 2010
- 06:28 PM
- 605 views
fMRI of Letter Processing in Children and Adults
by Livia in Reading and Word Recognition Research
Accessibility: Intermediate-Advanced
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...
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Turkeltaub PE, Flowers DL, Lyon LG, & Eden GF. (2008) Development of ventral stream representations for single letters. Annals of the New York Academy of Sciences, 13-29. PMID: 19076386
- April 6, 2010
- 07:34 PM
- 589 views
The Development of Visual Word Recognition
by Livia in Reading and Word Recognition Research
We’ve looked at brain regions and development during word related tasks (word generation, reading and repeating), but we haven’t yet looked at a straight up study of word recognition and development.
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
... Read more »
Turkeltaub, P., Gareau, L., Flowers, D., Zeffiro, T., & Eden, G. (2003) Development of neural mechanisms for reading. Nature Neuroscience, 6(7), 767-773. DOI: 10.1038/nn1065
- June 24, 2010
- 12:15 AM
- 582 views
A Meta-Analysis of Dyslexia Brain Imaging Studies
by Livia in Reading and Word Recognition Research
Accessibility: Advanced
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...
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Richlan, F., Kronbichler, M., & Wimmer, H. (2009) Functional abnormalities in the dyslexic brain: A quantitative meta-analysis of neuroimaging studies. Human Brain Mapping, 30(10), 3299-3308. DOI: 10.1002/hbm.20752
- August 18, 2010
- 02:20 PM
- 574 views
Noise Exclusion Deficits in Dyslexia
by Livia in Reading and Word Recognition Research
Accessibility: Intermediate-Advanced
The human visual system includes two pathways, magnocellular and parvocellular, deriving from two types of retinal ganglion cells that project to different layers of the lateral geniculate nucleus. ...
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Sperling, A., Lu, Z., Manis, F., & Seidenberg, M. (2005) Deficits in perceptual noise exclusion in developmental dyslexia. Nature Neuroscience. DOI: 10.1038/nn1474
- April 21, 2010
- 06:42 PM
- 565 views
Posterior Brain Differences in Children with Dyslexia
by Livia in Reading and Word Recognition Research
Accessibility: Intermediate-Advanced
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...
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Shaywitz, B. (2002) Disruption of posterior brain systems for reading in children with developmental dyslexia. Biological Psychiatry, 52(2), 101-110. DOI: 10.1016/S0006-3223(02)01365-3
- June 22, 2011
- 05:24 AM
- 563 views
N1 Specialization in Children with Dyslexia
by Livia in Reading and Word Recognition Research
Accessibility: Advanced
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 stronger for words than for symbols. We will refer to the words minus symbols difference as “N1 specialization for words .” Pre-reading kindergartners do not have this N1 specialization, while second graders have a stronger N1 specialization compared to adults. Today we focus on children with dyslexia.
As you might've guessed, Maurer and colleagues did the same experiment on children with dyslexia as well (see previous article for more information on what they did). These are the findings:
1. N1 specialization for words over symbols was much reduced in dyslexic second graders compared to normal reading second graders.
2. N1 specialization correlated with reading speed in second graders.
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.
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.
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. Brain : a journal of neurology, 130 (Pt 12), 3200-10 PMID: 17728359What is it that transforms a page full of words into an experience that moves us and leaves us changed? K. Okada From Words to Brain
... Read more »
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. Brain : a journal of neurology, 130(Pt 12), 3200-10. PMID: 17728359
- April 12, 2011
- 03:31 PM
- 556 views
The N1 Component in Second Graders
by Livia in Reading and Word Recognition Research
Accessibility: Advanced
Last week, we learned that the N1 component in normal reading adults differentiated between words and symbols, while the N1 component in pre-reading kindergartners 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 2005 paper when the kids were in second grade to see how their brain activity changed after two years of reading instruction.
These were their findings:
1. The N1 component differentiates between words and simple strings in the second graders.
2. Second graders actually had a greater words/symbols N1 difference than adults.*
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.
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.
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.
* Amplitudes in general were bigger in the second graders, but the difference held when amplitudes were normalized between children and adults
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. NeuroImage, 33 (2), 749-58 PMID: 16920367
What is it that transforms a page full of words into an experience that moves us and leaves us changed? K. Okada From Words to Brain
... Read more »
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. NeuroImage, 33(2), 749-58. PMID: 16920367
- June 22, 2011
- 05:24 AM
- 555 views
N1 Specialization in Children with Dyslexia
by Livia in Reading and Word Recognition Research
Accessibility: Advanced
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 stronger for words than for symbols. We will refer to the words minus symbols difference as “N1 specialization for words .” Pre-reading kindergartners do not have this N1 specialization, while second graders have a stronger N1 specialization compared to adults. Today we focus on children with dyslexia.
As you might've guessed, Maurer and colleagues did the same experiment on children with dyslexia as well (see previous article for more information on what they did). These are the findings:
1. N1 specialization for words over symbols was much reduced in dyslexic second graders compared to normal reading second graders.
2. N1 specialization correlated with reading speed in second graders.
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.
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.
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. Brain : a journal of neurology, 130 (Pt 12), 3200-10 PMID: 17728359What is it that transforms a page full of words into an experience that moves us and leaves us changed? K. Okada From Words to Brain
... Read more »
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. Brain : a journal of neurology, 130(Pt 12), 3200-10. PMID: 17728359
- May 24, 2010
- 06:10 PM
- 523 views
Evidence Suggesting that Specialized Visual Regions Are Formed by Pruning in Early Childhood
by Livia in Reading and Word Recognition Research
There 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.
How do these specialized...
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Cantlon JF, Pinel P, Dehaene S, & Pelphrey KA. (2010) Cortical Representations of Symbols, Objects, and Faces Are Pruned Back during Early Childhood. Cerebral cortex (New York, N.Y. : 1991). PMID: 20457691
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