Blog Archives

Evidence for right hemisphere phonology in a backward masking task

The extent to which orthographic and phonological processes are available during the initial moments of word recognition within each hemisphere is under specified, particularly for the right hemisphere. Few studies have investigated whether each hemisphere uses orthography and phonology under constraints that restrict the viewing time of words and reduce overt phonological demands. The current study used backward masking in the divided visual field paradigm to explore hemisphere differences in the availability of orthographic and phonological word recognition processes. A 20 ms and 60 ms SOA were used to track the time course of how these processes develop during pre-lexical moments of word recognition. Nonword masks varied in similarity to the target words such that there were four types: orthographically and phonologically similar, orthographically but not phonologically similar, phonologically but not orthographically similar and unrelated. The results showed the left hemisphere has access to both orthography and phonology early in the word recognition process. With more time to process the stimulus, the left hemisphere is able to use phonology which benefits word recognition to a larger extent than orthography. The right hemisphere also demonstrates access to both orthography and phonology in the initial moments of word recognition, however, orthographic similarity improves word recognition to a greater extent than phonological similarity.

from Brain and Language

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Neural basis of single-word reading in Spanish–English bilinguals

Brain imaging studies have identified a left-lateralized network of regions that are engaged when monolinguals read. However, for individuals who are native speakers of two languages, it is unclear whether this pattern of activity is maintained across both languages or if it deviates according to language-specific properties. We used functional magnetic resonance imaging to investigate single-word processing in Spanish and in English in 12 proficient early Spanish–English bilinguals matched in skill level in both languages. Word processing in Spanish engaged the left inferior frontal and left middle temporal gyri. Word processing in English activated the left inferior frontal, middle frontal, and fusiform gyri extending to inferior temporal gyrus and the right middle temporal gyrus extending into superior temporal sulcus. The comparison of reading in Spanish greater than reading in English revealed involvement of the left middle temporal gyrus extending into the superior temporal sulcus. English greater than Spanish, however, demonstrated greater engagement of the left middle frontal gyrus extending into the superior frontal gyrus. We conclude that although word processing in either language activates classical areas associated with reading, there are language-specific differences, which can be attributed to the disparity in orthographic transparency. English, an orthographically deep language, may require greater engagement of the frontal regions for phonological coding, whereas Spanish allows increased access to semantic processing via the left middle temporal areas. Together, these results suggest that bilinguals will show adjustments to the typical neural representation of reading as necessitated by the demands of the orthography.

from Human Brain Mapping

Orthographic context and the acquisition of orthographic knowledge in normal and dyslexic readers

We tested the hypothesis that the acquisition of orthographic knowledge of novel words that are presented in an indistinct context, that is a context with many orthographically similar words, would be more difficult for dyslexic than for normal readers. Participants were 19 Dutch dyslexic children (mean age 10;9 years), 20 age-matched and 20 reading-age-matched normal readers. During training the children repeatedly read a series of nonwords in a distinct (KWOG with KWES and SNAR) and an indistinct (KWOG with KWOS and KROG) orthographic context. At posttest, the dyslexic children were slower but more accurate in the reading of nonwords if these had been acquired in an indistinct than in a distinct training context. In normal readers context did not have an effect. We argue that dyslexic children’s sensitivity to orthographic context is due to their problems in the acquisition of fully specified orthographic representations causing interference by similar words. Copyright © 2011 John Wiley & Sons, Ltd.

from Dyslexia

Dyslexia in regular orthographies: manifestation and causation

This article summarizes our research on the manifestation of dyslexia in German and on cognitive deficits, which may account for the severe reading speed deficit and the poor orthographic spelling performance that characterize dyslexia in regular orthographies. An only limited causal role of phonological deficits (phonological awareness, phonological STM, and rapid naming) for the emergence of reading fluency and spelling deficits is inferred from two large longitudinal studies with assessments of phonology before learning to read. A review of our cross-sectional studies provides no support for several cognitive deficits (visual–attention deficit, magnocellular dysfunction, skill automatization deficit, and visual–sequential memory deficit), which were proposed as alternatives to the phonological deficit account. Finally, a revised version of the phonological deficit account in terms of a dysfunction in orthographic–phonological connectivity is proposed. Copyright © 2010 John Wiley & Sons, Ltd.

from Dyslexia

An examination of orthographic and phonological processing using the task-choice procedure

The task-choice procedure provides a way for assessing whether stimuli are processed immediately upon presentation and in parallel with other cognitive operations. In this procedure, the task changes on a trial-by-trial basis and the cue informing participants about the task appears either before or simultaneously with the target, which is either degraded or clear. Of interest is whether the effect of stimulus clarity will disappear when the cue is presented simultaneously with the target, suggesting capacity-free processing, or whether the effect of stimulus clarity will remain, suggesting target processing is delayed. Besner and Care developed this procedure using nonword targets and found that phonological information was not extracted in parallel with deciphering the task cue. The current experiment examined whether phonological and orthographic information could be extracted from word and nonword stimuli in a capacity-free manner. Results indicate that in both tasks some processing does occur in a capacity-free manner when words are used but not when nonwords are used. These data may be consistent with interactive activation models which posit top-down lexical connections that facilitate the extraction of sublexical codes.

from Language and Cognitive Processes

The weight of skill: Interindividual variability of reading related brain activation patterns in fluent readers

Neuroimaging studies of reading have so far mainly focused on the description of brain regions involved in processing writ words, particularly through approaches revealing the average activation pattern of entire groups of subjects. The aim of the present study was to contribute to the question of functional inter-individual variability of reading, and investigate whether reading can rely on different brain activation patterns, even in literate subjects, in a way that reflects their level of proficiency with written material. The present fMRI results obtained with a group of 33 literate subjects are consistent with models of reading postulating the existence of two routes to access words. They show that subject’s proficiency with written words is one factor that can shape the amount with which subjects rely on one route or the other. An essential functional set of brain regions was found to be reliably activated by each subject of our group, and its implication did not vary as a function of the reader’s skill. This set comprises regions devoted to the visual analysis of words (bilateral occipital regions and the left occipito-temporal junction), access to semantics (the basal temporal language area) and pronunciation (left rolandic sulcus) and could correspond to a direct access to words. Lower skilled readers showed a greater involvement of additional regions related to the grapho-phonological conversion of words. The deactivations observed in these regions for the most proficient readers indicate a functional independence of the two routes to access words.

from the Journal of Neurolinguistics

Modulation of brain regions involved in word recognition by homophonous stimuli: An fMRI study

We used rapid event-related fMRI to explore factors modulating the activation of orthographic and phonological representations of print during a visual lexical decision task. Stimuli included homophonous word and nonword stimuli (MAID, BRANE), which have been shown behaviorally to produce longer response times due to phonological mediation effects. We also manipulated participants’ reliance on orthography by varying the extent to which nonword foils were orthographically typical (wordlike context) or atypical (non-wordlike context) of real words. Key findings showed that reading low frequency homophones in the wordlike context produced activation in regions associated with phonological processing (i.e., opercular region of the left inferior frontal gyrus [IFG; BA 44]), the integration of orthography and phonology (i.e., the inferior parietal lobule (IPL), and lexicosemantic processing (i.e., left middle temporal gyrus, [MTG]). Pseudohomophones in the wordlike context produced greater activity relative to other nonword trials in regions engaged during both phonological processing (i.e., left IFG/precentral gyrus; BA 6/9]), and semantic processing (triangular region of the left IFG; BA 47). Homophonous effects in the non-wordlike context were primarily isolated to medial extrastriate regions, hypothesized to be involved in low level visual processing and not reading-related processing per se. These findings demonstrate that the degree to which phonological and orthographic representations of print are activated depends not only on homophony, but also on the word-likeness of nonword stimuli. Implications for models of visual word recognition are discussed.

from Brain Research

Task effects in the mid-fusiform gyrus: A comparison of orthographic, phonological, and semantic processing of Chinese characters

The left mid-fusiform gyrus is repeatedly reported to be involved in visual word processing. Nevertheless, it is controversial whether this area responds to orthographic processing of reading. To examine this idea, neural activity was measured using functional magnetic resonance imaging in the present study while subjects performed phonological, semantic, and orthographic tasks with Chinese characters under equivalent task difficulties. One region in the left mid-fusiform gyrus exhibited greater activity during the orthographic task than during the phonological and semantic tasks, which did not differ, suggesting that this region is involved in orthographic processing to a greater extent than phonological or semantic processing. In addition, a region in the right mid-fusiform gyrus exhibited a similar effect. This right mid-fusiform activity may relate to the use of pictorial Chinese characters.

from Brain and Language

Children with reading difficulties show differences in brain regions associated with orthographic processing during spoken language processing

We explored the neural basis of spoken language deficits in children with reading difficulty, specifically focusing on the role of orthography during spoken language processing. We used functional magnetic resonance imaging (fMRI) to examine differences in brain activation between children with reading difficulties (aged 9-to-15 years) and age-matched children with typical achievement during an auditory rhyming task. Both groups showed activation in bilateral superior temporal gyri (BA 42, 22), a region associated with phonological processing, with no significant between-groups differences. Interestingly, typically achieving children, but not children with reading difficulties, showed activation of left fusiform cortex (BA 37), a region implicated in orthographic processing. Furthermore, this activation was significantly greater for typically achieving children compared to those with reading difficulties. These findings suggest that typical children automatically activate orthographic representations during spoken language processing, while those with reading difficulties do not. Follow-up analyses revealed that the intensity of the activation in the fusiform gyrus was associated with significantly stronger behavioral conflict effects in typically achieving children only (i.e., longer latencies to rhyming pairs with orthographically dissimilar endings than to those with identical orthographic endings; jazz-has vs. cat-hat). Finally, for reading disabled children, a positive correlation between left fusiform activation and non-word reading was observed, such that greater access to orthography was related to decoding ability. Taken together, the results suggest the integration of orthographic and phonological processing are directly related to reading ability.

from Brain Research

Neural Systems for Reading Aloud: A Multiparametric Approach

Reading aloud involves computing the sound of a word from its visual form. This may be accomplished 1) by direct associations between spellings and phonology and 2) by computation from orthography to meaning to phonology. These components have been studied in behavioral experiments examining lexical properties such as word frequency; length in letters or phonemes; spelling–sound consistency; semantic factors such as imageability, measures of orthographic, or phonological complexity; and others. Effects of these lexical properties on specific neural systems, however, are poorly understood, partially because high intercorrelations among lexical factors make it difficult to determine if they have independent effects. We addressed this problem by decorrelating several important lexical properties through careful stimulus selection. Functional magnetic resonance imaging data revealed distributed neural systems for mapping orthography directly to phonology, involving left supramarginal, posterior middle temporal, and fusiform gyri. Distinct from these were areas reflecting semantic processing, including left middle temporal gyrus/inferior-temporal sulcus, bilateral angular gyrus, and precuneus/posterior cingulate. Left inferior frontal regions generally showed increased activation with greater task load, suggesting a more general role in attention, working memory, and executive processes. These data offer the first clear evidence, in a single study, for the separate neural correlates of orthography–phonology mapping and semantic access during reading aloud.

from Cerebral Cortex

An examination of orthographic and phonological processing using the task-choice procedure

The task-choice procedure provides a way for assessing whether stimuli are processed immediately upon presentation and in parallel with other cognitive operations. In this procedure, the task changes on a trial-by-trial basis and the cue informing participants about the task appears either before or simultaneously with the target, which is either degraded or clear. Of interest is whether the effect of stimulus clarity will disappear when the cue is presented simultaneously with the target, suggesting capacity-free processing, or whether the effect of stimulus clarity will remain, suggesting target processing is delayed. Besner and Care developed this procedure using nonword targets and found that phonological information was not extracted in parallel with deciphering the task cue. The current experiment examined whether phonological and orthographic information could be extracted from word and nonword stimuli in a capacity-free manner. Results indicate that in both tasks some processing does occur in a capacity-free manner when words are used but not when nonwords are used. These data may be consistent with interactive activation models which posit top-down lexical connections that facilitate the extraction of sublexical codes.

from Language and Cognitive Processes

Learning to assign lexical stress during reading aloud: Corpus, behavioral, and computational investigations

Models of reading aloud have tended to focus on the mapping between graphemes and phonemes in monosyllables. Critical adaptations of these models are required when considering the reading of polysyllables, which constitute over 90% of word types in English. In this paper, we examined one such adaptation – the process of stress assignment in learning to read. We used a triangulation of corpus, behavioral, and computational modeling techniques. A corpus analysis of age-appropriate reading materials for children aged 5–12 years revealed that the beginnings and endings of English bisyllabic words are highly predictive of stress position, but that endings are more reliable cues in texts for older children. Children aged 5–12 years revealed sensitivity to both the beginnings and endings when reading nonwords, but older children relied more on endings for determining stress assignment. A computational model that learned to map orthography onto stress showed the same age-related trajectory as the children when assigning stress to nonwords. These results reflect the gradual process of learning the statistical properties of written input and provide key constraints for adequate models of reading aloud.

from the Journal of Memory and Language

Predictors of Response to Intervention of Word Reading Fluency in Dutch

The objective of this study was to investigate the contribution of rapid digit naming, phonological memory, letter sound naming, and orthographic knowledge to the prediction of responsiveness to a school-based, individual intervention of word reading fluency problems of 122 Dutch second and third graders whose reading scores were below the 10th percentile in comparison with the normative group. Degree of responsiveness was determined by comparison of a pre- and posttest measure of word reading fluency with a 6-month interval. At posttest, 38% of the children had improved their reading scores above the 10th percentile. Maintenance scores revealed no significant growth on average, confirming that word reading fluency skills of poor readers are hard to remediate. Except rapid digit naming, none of the measures predicted responsiveness after controlling for the autoregressive effect of initial performance on fluency of word reading. A large part of the variance remained unexplained, supporting the advantage of a response-to-intervention approach above traditional psychometric testing to identify severe reading disabilities.

from the Journal of Learning Disabilities

The Acquisition of Mental Orthographic Representations for Reading and Spelling Development

Word-level reading and spelling skills support reading comprehension and writing composition. Accurate and fluent word-level reading and spelling are facilitated when individuals have clear mental orthographic representations (MOR) that permit them to quickly recognize and recall the visual representation of a word, freeing up memory and attentional resources for comprehending or composing text. It is interesting that the role MOR development plays in early literacy development has received minimal attention. This article, based on a presentation at the 2007 Katharine G. Butler Symposium on Child Language, first reviews the literature that supports a sequential view of MOR acquisition followed by recent findings that support MOR development as a unique and independently developing skill. A general overview of three investigations designed to determine the independence and contribution of MOR development to children’s acquisition of word-level literacy skills is provided. Suggestions for further research and initial clinical implications are made based on the results of the investigations and the current literature on MOR development.

from Communications Disorders Quarterly

What type of computer-assisted exercise supports young less skilled spellers in resolving problems in open and closed syllable words?

from Annals of Dyslexia

Abstract Dutch bisyllabic words containing open and closed syllables are particularly difficult to spell for children. What kind of support in spelling exercises improves the spelling of these words the most? Two extensions of a commonly used dictation exercise were tested: less skilled spellers in grade 2 (n = 50; 7 years and 10 months) either received explicit syllabic segmentation cues or received spelling cues by means of a visual preview. Comparisons between pre-, post-, and retention tests of spelling skill showed that extra syllabic cues did not show a significant improvement beyond normal spelling dictation and that visual preview was most effective as compared to the other types of training. The findings suggest that word-specific knowledge can effectively be improved by exposure to the correct letter pattern during exercises in spelling and seems to result in lasting improvement of word-specific orthographic representations, at least for 5 weeks.