A combined fMRI study of typed spelling and reading

Atypical characteristic changes of surface morphology and structural covariance network in developmental dyslexia

BACKGROUND

Developmental dyslexia (DD) is a neurodevelopmental disorder that is characterized by difficulties with all aspects of information acquisition in the written word, including slow and inaccurate word recognition. The neural basis behind DD has not been fully elucidated.

METHOD

The study included 22 typically developing (TD) children, 16 children with isolated spelling disorder (SpD), and 20 children with DD. The cortical thickness, folding index, and mean curvature of Broca's area, including the triangular part of the left inferior frontal gyrus (IFGtriang) and the opercular part of the left inferior frontal gyrus, were assessed to explore the differences of surface morphology among the TD, SpD, and DD groups. Furthermore, the structural covariance network (SCN) of the triangular part of the left inferior frontal gyrus was analyzed to explore the changes of structural connectivity in the SpD and DD groups.

RESULTS

The DD group showed higher curvature and cortical folding of the left IFGtriang than the TD group and SpD group. In addition, compared with the TD group and the SpD group, the structural connectivity between the left IFGtriang and the left middle-frontal gyrus and the right mid-orbital frontal gyrus was increased in the DD group, and the structural connectivity between the left IFGtriang and the right precuneus and anterior cingulate was decreased in the DD group.

CONCLUSION

DD had atypical structural connectivity in brain regions related to visual attention, memory and which might impact the information input and integration needed for reading and spelling.

White matter associations with spelling performance

Multiple neurocognitive processes are involved in the highly complex task of producing written words. Yet, little is known about the neural pathways that support spelling in healthy adults. We assessed the associations between performance on a difficult spelling-to-dictation task and microstructural properties of language-related white matter pathways, in a sample of 73 native English-speaking neurotypical adults. Participants completed a diffusion magnetic resonance imaging scan and a cognitive assessment battery. Using constrained spherical deconvolution modeling and probabilistic tractography, we reconstructed dorsal and ventral white matter tracts of interest, bilaterally, in individual participants. Spelling associations were found in both dorsal and ventral stream pathways. In high-performing spellers, spelling scores significantly correlated with fractional anisotropy (FA) within the left inferior longitudinal fasciculus, a ventral stream pathway. In low-performing spellers, spelling scores significantly correlated with FA within the third branch of the right superior longitudinal fasciculus, a dorsal pathway. An automated analysis of spelling errors revealed that high- and low- performing spellers also differed in their error patterns, diverging primarily in terms of the orthographic distance between their errors and the correct spelling, compared to the phonological plausibility of their spelling responses. The results demonstrate the complexity of the neurocognitive architecture of spelling. The distinct white matter associations and error patterns detected in low- and high- performing spellers suggest that they rely on different cognitive processes, such that high-performing spellers rely more on lexical-orthographic representations, while low-performing spellers rely more on phoneme-to-grapheme conversion.

Written language preservation in glioma patients undergoing awake surgery: The value of tailored intra-operative assessment

Written language is increasingly important, as contemporary society strongly relies on text-based communication. Nonetheless, in neurosurgical practice, language preservation has classically focused on spoken language. The current study aimed to evaluate the potential role of intra-operative assessments in the preservation of written language skills in glioma patients undergoing awake surgery. It is the first feasibility study to use a standardized and detailed Written language battery in glioma patients undergoing awakening surgery. Reading and spelling were assessed pre- and post-operatively in eleven patients. Intra-operatively, 7 cases underwent written language assessment in addition to spoken object naming. Results show that reading and spelling deficits may arise before and after glioma surgery and that written language may be differently affected than spoken language. In our case series, task-specific preservation of function was obtained in all cases when a specific written language skill was monitored intra-operatively. However, the benefits of intra-operative testing did not always generalize, and non-monitored written language tasks may not be preserved. Hence, when a specific written language skill needs to be preserved, to facilitate return to work and maintain quality of life, results indicate that intra-operative assessment of that skill is advised. An illustrative case report demonstrates how profile analyses can be used pre-operatively to identify cognitive components at risk and intra-operatively to preserve written language abilities in clinical practice.

Underlying functions associated with keyboarding performance of elementary-school students

BACKGROUND

Keyboarding (Typing) is a major writing mode in educational settings in addition to, or as an alternative to, handwriting. Therefore, it is important that occupational therapists become experts on this activity, to support students' performance. Yet, the knowledge of keyboarding performance of elementary-school students, and the underlying functions it entails, is limited.

AIM

To compare keyboarding performance (speed and accuracy) of 4th-grade students in copying and dictation keyboarding tasks, and to examine the role of underlying functions in predicting keyboarding performance.

MATERIAL AND METHODS

The sample consisted of 57 4th-grade students, recruited from 2 elementary schools. Students were tested for reading speed, attention shifting, fine-motor skills, kinaesthetic awareness, and keyboarding performance.

RESULTS

Keyboarding performance differed in the copying and dictation tasks. Reading speed was the major underlying function predicting keyboarding performance in both tasks. Additionally, kinaesthetic awareness had a low, negative correlation with dictation accuracy.

CONCLUSIONS

When occupational therapists assess students' keyboarding performance, they should use various tasks. Additionally, therapists should consider students' reading speed and kinaesthetic awareness, as they may explain keyboarding performance. This knowledge may also support decision-making when considering keyboarding as an alternative writing mode for students with handwriting difficulties.

Word Reading and Spelling Processing and Acquired Dyslexia post Unilateral Stroke

This study investigates the performance of adults with cerebrovascular lesion in the right hemisphere (RHL) or left hemisphere (LHL) in word reading (TLPP) and spelling (TEPP) tasks based on the dual-route models. A total of 85 adults were assessed, divided into three groups: 10 with RHL, 15 with LHL, and 60 neurologically healthy ones. The performance of the three groups was compared in terms of the characteristics of the words (regularity, frequency, and length) and pseudowords (length), error types, and psycholinguistic effects. A cluster analysis was performed to investigate the profiles of the reading. The LHL group showed lower scores in reading and spelling tasks of words and pseudowords, as well as a higher frequency of errors. Four LHL cases were found to have an acquired dyslexia profile. This study highlights that the tasks developed in Brazil are in accordance with theoretical models of written language, and the results point to the heterogeneous performance of the cases with acquired dyslexia.

A single case neuroimaging study of tickertape synesthesia

Reading acquisition is enabled by deep changes in the brain's visual system and language areas, and in the links subtending their collaboration. Disruption of those plastic processes commonly results in developmental dyslexia. However, atypical development of reading mechanisms may occasionally result in ticker-tape synesthesia (TTS), a condition described by Francis Galton in 1883 wherein individuals "see mentally in print every word that is uttered (…) as from a long imaginary strip of paper". While reading is the bottom-up translation of letters into speech, TTS may be viewed as its opposite, the top-down translation of speech into internally visualized letters. In a series of functional MRI experiments, we studied MK, a man with TTS. We showed that a set of left-hemispheric areas were more active in MK than in controls during the perception of normal than reversed speech, including frontoparietal areas involved in speech processing, and the Visual Word Form Area, an occipitotemporal region subtending orthography. Those areas were identical to those involved in reading, supporting the construal of TTS as upended reading. Using dynamic causal modeling, we further showed that, parallel to reading, TTS induced by spoken words and pseudowords relied on top-down flow of information along distinct lexical and phonological routes, involving the middle temporal and supramarginal gyri, respectively. Future studies of TTS should shed new light on the neurodevelopmental mechanisms of reading acquisition, their variability and their disorders.

Positive changes to written language following phonological treatment in logopenic variant primary progressive aphasia: Case report

Phonological impairment contributes to deficits in repetition and spoken naming in logopenic variant Primary Progressive Aphasia (lvPPA), but weakened phonology can also affect written language skills. In this experimental case report, we demonstrate phonological text agraphia in a 71-year-old woman in the early stages of lvPPA that undermined her ability to write meaningful, grammatical sentences. We investigated the therapeutic value of a rigorous treatment protocol to strengthen phonological manipulation skills coupled with transcranial direct current stimulation (tDCS). Intervention took place 5 days a week for 2 weeks with active tDCS, followed by a 2-month rest period, and then a second period of phonological treatment with sham tDCS. Over the course of treatment, our participant demonstrated improved phonological transcoding and manipulation skills as well as marked improvement in the proportion of grammatically well-formed, meaningful written narratives. Improvements in spelling and letter selection were also observed. Treatment gains were documented during phonological intervention in both active tDCS and sham treatment phases and were maintained 2 months after the conclusion of intervention. Importantly, improvements were observed in the context of a progressive disorder. These data present compelling evidence regarding the impairment-based approach that targets compromised phonological skills, presenting opportunity for improving functional written communication skills relevant to the everyday lives of individuals with lvPPA.

A Crossed Pure Agraphia by Graphemic Buffer Impairment following Right Orbito-Frontal Glioma Resection

Pure agraphias are caused by graphemic buffer damage. The graphemic buffer stores graphemic representations that handle the transition from spelling lexicon to writing or oral spellings. The authors report a case of a crossed pure agraphia, following the post-surgical removal of a right frontal low-grade glioma in a right-handed French patient. He presented a pure agraphia displaying the features of a graphemic buffer impairment. Our patient only made spelling errors, whereas repetition and other oral language abilities remained perfect. We found a greater number of errors for longer stimuli, increased errors for the medially located graphemes, and agraphia for both words and non-words and error types, essentially consisting of omissions, substitutions, and letter transpositions. We also observed no significant effect of word frequency on spelling errors, but word length affected the rate of errors. The particularity of this case was linked to right frontal subcortical injuries in a right-handed subject. To our knowledge, it is the first report of a crossed pure agraphia caused by graphemic buffer impairment. Further studies are needed in order to analyse the role of subcortical structures, particularly the caudate nucleus in the graphemic buffer during writing tasks, as well as the participation of the non-dominant hemisphere in writing language.

A connectivity model of the anatomic substrates underlying Gerstmann syndrome

The Gerstmann syndrome is a constellation of neurological deficits that include agraphia, acalculia, left–right discrimination and finger agnosia. Despite a growing interest in this clinical phenomenon, there remains controversy regarding the specific neuroanatomic substrates involved. Advancements in data-driven, computational modelling provides an opportunity to create a unified cortical model with greater anatomic precision based on underlying structural and functional connectivity across complex cognitive domains. A literature search was conducted for healthy task-based functional MRI and PET studies for the four cognitive domains underlying Gerstmann’s tetrad using the electronic databases PubMed, Medline, and BrainMap Sleuth (2.4). Coordinate-based, meta-analytic software was utilized to gather relevant regions of interest from included studies to create an activation likelihood estimation (ALE) map for each cognitive domain. Machine-learning was used to match activated regions of the ALE to the corresponding parcel from the cortical parcellation scheme previously published under the Human Connectome Project (HCP). Diffusion spectrum imaging-based tractography was performed to determine the structural connectivity between relevant parcels in each domain on 51 healthy subjects from the HCP database. Ultimately 102 functional MRI studies met our inclusion criteria. A frontoparietal network was found to be involved in the four cognitive domains: calculation, writing, finger gnosis, and left–right orientation. There were three parcels in the left hemisphere, where the ALE of at least three cognitive domains were found to be overlapping, specifically the anterior intraparietal area, area 7 postcentral (7PC) and the medial intraparietal sulcus. These parcels surround the anteromedial portion of the intraparietal sulcus. Area 7PC was found to be involved in all four domains. These regions were extensively connected in the intraparietal sulcus, as well as with a number of surrounding large-scale brain networks involved in higher-order functions. We present a tractographic model of the four neural networks involved in the functions which are impaired in Gerstmann syndrome. We identified a ‘Gerstmann Core’ of extensively connected functional regions where at least three of the four networks overlap. These results provide clinically actionable and precise anatomic information which may help guide clinical translation in this region, such as during resective brain surgery in or near the intraparietal sulcus, and provides an empiric basis for future study.

Functional MRI evidence for reorganization of language networks after stroke

In this chapter, we review fMRI evidence for language reorganization in individuals with poststroke aphasia. Several studies in the current literature have utilized fMRI as a tool to understand patterns of functional reorganization in poststroke aphasia. Consistent with previous models that have been proposed to explain the trajectory of language recovery, differential patterns of language processing and language recovery have been identified across individuals with poststroke aphasia in different stages of recovery. Overall, a global network breakdown typically occurs in the early stages of aphasia recovery, followed by normalization in "traditional" left hemisphere language networks. Depending on individual characteristics, right hemisphere regions and bilateral domain-general regions may be further recruited. The main takeaway of this chapter is that poststroke aphasia recovery does not depend on individual neural regions, but rather involves a complex interaction among regions in larger networks. Many of the unresolved issues and contrastive findings in the literature warrant further research with larger groups of participants and standard protocols of fMRI implementation.

Reading and Calculation Neural Systems and Their Weighted Adaptive Use for Programming Skills

Software programming is a modern activity that poses strong challenges to the human brain. The neural mechanisms that support this novel cognitive faculty are still unknown. On the other hand, reading and calculation abilities represent slightly less recent human activities, in which neural correlates are relatively well understood. We hypothesize that calculus and reading brain networks provide joint underpinnings with distinctly weighted contributions which concern programming tasks, in particular concerning error identification. Based on a meta-analysis of the core regions involved in both reading and math and recent experimental evidence on the neural basis of programming tasks, we provide a theoretical account that integrates the role of these networks in program understanding. In this connectivity-based framework, error-monitoring processing regions in the frontal cortex influence the insula, which is a pivotal hub within the salience network, leading into efficient causal modulation of parietal networks involved in reading and mathematical operations. The core role of the anterior insula and anterior midcingulate cortex is illuminated by their relation to performance in error processing and novelty. The larger similarity that we observed between the networks underlying calculus and programming skills does not exclude a more limited but clear overlap with the reading network, albeit with differences in hemispheric lateralization when compared with prose reading. Future work should further elucidate whether other features of computer program understanding also use distinct weights of phylogenetically “older systems” for this recent human activity, based on the adjusting influence of fronto-insular networks. By unraveling the neural correlates of program understanding and bug detection, this work provides a framework to understand error monitoring in this novel complex faculty.

Neural patterns of word processing differ in children with dyslexia and isolated spelling deficit

There is an ongoing debate concerning the extent to which deficits in reading and spelling share cognitive components and whether they rely, in a similar fashion, on sublexical and lexical pathways of word processing. The present study investigates whether the neural substrates of word processing differ in children with various patterns of reading and spelling deficits. Using functional magnetic resonance imaging, we compared written and auditory processing in three groups of 9-13-year olds (N = 104): (1) with age-adequate reading and spelling skills; (2) with reading and spelling deficits (i.e., dyslexia); (3) with isolated spelling deficits but without reading deficits. In visual word processing, both deficit groups showed hypoactivations in the posterior superior temporal cortex compared to typical readers and spellers. Only children with dyslexia exhibited hypoactivations in the ventral occipito-temporal cortex compared to the two groups of typical readers. This is the result of an atypical pattern of higher activity in the occipito-temporal cortex for non-linguistic visual stimuli than for words, indicating lower selectivity. The print-speech convergence was reduced in the two deficit groups. Impairments in lexico-orthographic regions in a reading-based task were associated primarily with reading deficits, whereas alterations in the sublexical word processing route could be considered common for both reading and spelling deficits. These findings highlight the partly distinct alterations of the language network related to reading and spelling deficits.

Word frequency effect in written production: Evidence from ERPs and neural oscillations

It has been widely documented that word frequency (WF) modulates language processing in various input and output modalities. WF effect has also been reported in the domain of written production; however, how WF affects written production is a controversial issue. The present study attempts to investigate the time course of and neural oscillation underlying the WF effect in handwritten production. Participants were asked to handwrite pictures names of high versus low WF, while concurrently recording EEG. EEG trials were extracted time-locked to picture onsets and then submitted to event-related potential analysis and time-frequency analysis. WF affected ERPs in the time windows of around 98-160 and 282-360 ms after picture onsets. More importantly, WF modulated the evoked and induced theta-band (4-8 Hz) neural oscillations in the time window of around 36-240 and 244-472 ms, respectively. Considering the time course of language production and the role of theta-band oscillation in long-term memory retrieval, we suggest that the two stages of the WF effect, respectively, reflect conceptual preparation and retrieval of orthographic word-forms in written production.

Clinical Pearls and Methods for Intraoperative Awake Language Mapping

Intraoperative language mapping of tumor and peritumor tissue is a well-established technique for avoiding permanent neurological deficits and maximizing extent of resection. Although there are several components of language that may be tested intraoperatively (eg, naming, writing, reading, and repetition), there is a lack of consistency in how patients are tested intraoperatively as well as the techniques involved to ensure safety during an awake procedure. Here, we review appropriate patient selection, neuroanesthetic techniques, cortical and subcortical language mapping stimulation paradigms, and selection of intraoperative language tasks used during awake craniotomies. We also expand on existing language mapping reviews by considering how intensity and timing of electrical stimulation may impact interpretation of mapping results.

The handwriting brain in middle childhood

While the brain network supporting handwriting has previously been defined in adults, its organization in children has never been investigated. We compared the handwriting network of 23 adults and 42 children (8- to 11-year-old). Participants were instructed to write the alphabet, the days of the week, and to draw loops while being scanned. The handwriting network previously described in adults (five key regions: left dorsal premotor cortex, superior parietal lobule (SPL), fusiform and inferior frontal gyri, and right cerebellum) was also strongly activated in children. The right precentral gyrus and the right anterior cerebellum were more strongly activated in adults than in children, while the left fusiform gyrus (FuG) was more strongly activated in children than in adults. Finally, we found that, contrary to adults, children recruited prefrontal regions to complete the writing task. This constitutes the first comparative investigation of the neural correlates of writing in children and adults. Our results suggest that the network supporting handwriting is already established in middle childhood. They also highlight the major role of prefrontal regions in learning this complex skill and the importance of right precentral regions and cerebellum in the performance of automated handwriting.

Children's neurodevelopment of reading is affected by China's language input system in the information era

Communications through electronic devices require knowledge in typewriting, typically with the pinyin input method in China. Yet, the over utilization of the pronunciation-based pinyin input method may violate the traditional learning processes of written Chinese, which involves abundant visual orthographic analysis of characters and repeated writing. We used functional magnetic resonance imaging to examine the influence of pinyin typing on reading neurodevelopment of intermediate Chinese readers (age 9-11). We found that, relative to less frequent pinyin users, more frequent pinyin users showed an overall weaker pattern of cortical activations in the left middle frontal gyrus, left inferior frontal gyrus, and right fusiform gyrus in performing reading tasks. In addition, more frequent pinyin typists had relatively less gray matter volume in the left middle frontal region, a site known to be crucial for Chinese reading. This study demonstrates that Chinese children's brain development in the information era is affected by the frequent use of the pinyin input method.

Dissociating the functions of superior and inferior parts of the left ventral occipito-temporal cortex during visual word and object processing

During word and object recognition, extensive activation has consistently been observed in the left ventral occipito-temporal cortex (vOT), focused around the occipito-temporal sulcus (OTs). Previous studies have shown that there is a hierarchy of responses from posterior to anterior vOT regions (along the y-axis) that corresponds with increasing levels of recognition - from perceptual to semantic processing, respectively. In contrast, the functional differences between superior and inferior vOT responses (i.e. along the z-axis) have not yet been elucidated. To investigate, we conducted an extensive review of the literature and found that peak activation for reading varies by more than 1 cm in the z-axis. In addition, we investigated functional differences between superior and inferior parts of left vOT by analysing functional MRI data from 58 neurologically normal skilled readers performing 8 different visual processing tasks. We found that group activation in superior vOT was significantly more sensitive than inferior vOT to the type of task, with more superior vOT activation when participants were matching visual stimuli for their semantic or perceptual content than producing speech to the same stimuli. This functional difference along the z-axis was compared to existing boundaries between cytoarchitectonic areas around the OTs. In addition, using dynamic causal modelling, we show that connectivity from superior vOT to anterior vOT increased with semantic content during matching tasks but not during speaking tasks whereas connectivity from inferior vOT to anterior vOT was sensitive to semantic content for matching and speaking tasks. The finding of a functional dissociation between superior and inferior parts of vOT has implications for predicting deficits and response to rehabilitation for patients with partial damage to vOT following stroke or neurosurgery.

Reading and spelling skills are differentially related to phonological processing: Behavioral and fMRI study

The manuscript reports a study on a large sample (N = 170) of Polish speaking 8-13 year old children, whose brain activation was measured in relation to tasks that require auditory phonological processing. We aimed to relate brain activation to individual differences in reading and spelling. We found that individual proficiency in both reading and spelling significantly correlated with activation of the left ventral occipito-temporal cortex encompassing the Visual Word Form Area which has been implicated in automatic orthographic activations. Reading but not spelling was found to correlate with activation in the left anterior dorsal stream (anterior supramarginal and postcentral gyri). Our results indicate that the level of both reading and spelling is related to activity in areas involved in the storage of fine-grained orthographic representations. However, only the reading level is uniquely related to activity of regions responsible for the articulation, motor planning and grapheme-to-phoneme correspondence, which form the basis for effective decoding skill.

Written Verb Naming Improves After tDCS Over the Left IFG in Primary Progressive Aphasia

Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique, is an effective adjunct to naming treatments in post-stroke aphasia and primary progressive aphasia (PPA). Enhanced performance in oral and written naming and spelling of nouns with tDCS has been quantified in detail, but it is not known whether it is effective for verb treatment in PPA. We addressed the question of whether performance in naming and spelling of verbs can be augmented with anodal tDCS over the left inferior frontal gyrus (IFG). We compared tDCS coupled with oral and written verb naming/spelling treatment with oral and written verb naming/spelling treatment alone. In a double-blind, sham-controlled, crossover design, 11 participants with logopenic or non-fluent variant PPA received approximately 15 consecutive sessions of anodal tDCS and sham over the left IFG coupled with oral and written verb-naming + spelling treatment. Written verb-naming performance improved significantly more for trained verbs in the tDCS than the sham condition. Importantly, tDCS effects generalized to untrained items for written verb naming and were significant even at 2 months post-treatment. We conclude that tDCS over the left IFG can improve written verb naming and spelling in PPA.

Reliability and practical clinical application of an accelerometer-based dual-task gait balance control assessment

BACKGROUND

Gait balance control assessment using whole body center of mass (COM) kinematic measures in concussed individuals reveals persistent balance deficits up to two months post-injury. A reliable and clinically practical gait balance control assessment leveraging similar kinematic measures is necessary to improve concussion assessment and management.

RESEARCH QUESTION

Can peak accelerations collected during a dual-task (DT) gait assessment from a single low back placed accelerometer be measured reliably on different days, by different raters, in different environments, and be practically applied in a Division One (D1) athletics program?

METHODS

A single accelerometer placed on the low back over the L5 vertebra was utilized with a DT gait analysis protocol. Twenty (10 F) healthy participants performed the assessment in a laboratory and non-laboratory environment, on two separate days, and with two different raters. Eight gait event specific peak accelerations along three orthogonal axes were collected. In addition, data were collected from a cohort of 14 D1 female soccer players during a single assessment to explore the practical clinical application.

RESULTS

Cronbach's α values for the eight metrics ranged from 0.881 to 0.980 and ICC values from 0.868 to 0.987. Average assessment time for the 14 D1 female athletes was 8.50 ± 0.58 min, and significant differences between walking conditions were identified for Vert Accel 1 (p < .01), Vert Accel 2 (p = .01), and A-P Accel (p < .01).

SIGNIFICANCE

High Cronbach's α and ICC values coupled with a short assessment time and sensitivity to differences in gait balance control indicate our testing apparatus and protocol are both reliable and clinically practical. Additionally, gait event specific peak accelerations from a single accelerometer can detect subtle changes in gait balance control and may facilitate improvements in sport-related concussion diagnosis and return to activity decision making.

Reductions in GABA following a tDCS-language intervention for primary progressive aphasia

Transcranial direct current stimulation (tDCS) has shown efficacy in augmenting the effects of language therapy in primary progressive aphasia (PPA). The mechanism of action of tDCS is not understood, but preliminary work in healthy adults suggests it modulates γ-aminobutyric acid (GABA) levels to create an environment optimal for learning. It is unknown if this proposed mechanism translates to aging or neurodegenerative conditions. This study tested the hypothesis that tDCS reduces GABA at the stimulated tissue in PPA. We applied GABA-edited magnetic resonance spectroscopy to quantify GABA levels before and after a sham-controlled tDCS intervention with language therapy in PPA. All participants showed improvements but those receiving active tDCS showed significantly greater language improvements compared to sham both immediately after the intervention and at 2-month follow-up. GABA levels in the targeted tissue decreased from baseline after the intervention and remained decreased 2 months after the intervention. This work supports the hypothesis that tDCS modulates GABAergic inhibition to augment learning and is clinically useful for PPA combined with language therapy.

Electrical brain stimulation in different variants of primary progressive aphasia: A randomized clinical trial

Introduction

Transcranial direct current stimulation (tDCS) has been recently shown to improve language outcomes in primary progressive aphasia (PPA) but most studies are small and the influence of PPA variant is unknown.

Methods

Thirty-six patients with PPA participated in a randomized, sham-controlled, double-blind, within-subject crossover design for 15 daily sessions of stimulation coupled with written naming/spelling therapy. Outcome measures were letter accuracy of treated and untreated words immediately after and at 2 weeks and 2 months posttreatment.

Results

tDCS treatment was more effective than sham: gains for treated words were maintained 2 months posttreatment; gains from tDCS also generalized to untreated words and were sustained 2 months posttreatment. Different effects were obtained for each PPA variant, with no tDCS advantage for semantic variant PPA.

Discussion

The study supports using tDCS as an adjunct to written language interventions in individuals with logopenic or nonfluent/agrammatic PPA seeking compensatory treatments in clinical settings.

Voxel-based lesion analysis of brain regions underlying reading and writing

The neural basis of reading and writing has been a source of inquiry as well as controversy in the neuroscience literature. Reading has been associated with both left posterior ventral temporal zones (termed the "visual word form area") as well as more dorsal zones, primarily in left parietal cortex. Writing has also been associated with left parietal cortex, as well as left sensorimotor cortex and prefrontal regions. Typically, the neural basis of reading and writing are examined in separate studies and/or rely on single case studies exhibiting specific deficits. Functional neuroimaging studies of reading and writing typically identify a large number of activated regions but do not necessarily identify the core, critical hubs. Last, due to constraints on the functional imaging environment, many previous studies have been limited to measuring the brain activity associated with single-word reading and writing, rather than sentence-level processing. In the current study, the brain correlates of reading and writing at both the single- and sentence-level were studied in a large sample of 111 individuals with a history of chronic stroke using voxel-based lesion symptom mapping (VLSM). VLSM provides a whole-brain, voxel-by-voxel statistical analysis of the role of distinct regions in a particular behavior by comparing performance of individuals with and without a lesion at every voxel. Rather than comparing individual cases or small groups with particular behavioral dissociations in reading and writing, VLSM allowed us to analyze data from a large, well-characterized sample of stroke patients exhibiting a wide range of reading and writing impairments. The VLSM analyses revealed that reading was associated with a critical left inferior temporo-occipital focus, while writing was primarily associated with the left supramarginal gyrus. Separate VLSM analyses of single-word versus sentence-level reading showed that sentence-level reading was uniquely associated with anterior to mid-portions of the middle and superior temporal gyri. Both single-word and sentence-level writing overlapped to a great extent in the left supramarginal gyrus, but sentence-level writing was associated with additional underlying white matter pathways such as the internal capsule. These findings suggest that critical aspects of reading and writing processes diverge, with reading relying critically on the ventral visual recognition stream and writing relying on a dorsal visuo-spatial-motor stream.

Do reading and spelling share orthographic representations? Evidence from developmental dysgraphia

Both spelling and reading depend on knowledge of the spellings of words. Despite this commonality, observed dissociations between spelling and reading in cases of acquired and developmental deficits suggest some degree of independence between the cognitive mechanisms involved in these skills. In this paper, we examine the relationship between spelling and reading in two children with developmental dysgraphia. For both children, we identified significant deficits in spelling that affected the processing of orthographic long-term memory representations of words. We then examined their reading skills for similar difficulties. Even with extensive testing, we found no evidence of a reading deficit for one of the children. We propose that there may be an underlying difficulty that specifically affects the learning of orthographic word representations for spelling. These results lead us to conclude that at least some components of lexical orthographic representation and processing develop with considerable independence in spelling and reading.

Recovery of orthographic processing after stroke: A longitudinal fMRI study

An intact orthographic processing system is critical for normal reading and spelling. Here we investigate the neural changes associated with impairment and subsequent recovery of the orthographic lexical processing system in an individual with an ischemic left posterior cerebral artery (PCA) stroke. This work describes a longitudinal case study of a patient, whose initials are MMY, with impairments in orthographic lexical processing for reading and spelling at stroke onset, and who recovered these skills within 1 year post stroke. We tested the hypothesis that this acute impairment to reading and spelling would be associated with a selective loss of neural activation in the left fusiform gyrus (FG), and that subsequent recovery would be associated with a gain of neural activation in this region. MMY's case provided a unique opportunity to assess the selectivity of neural changes because she demonstrated a behavioral recovery of naming as well; i.e., if there is neural recovery for reading and spelling, but not naming, then these neural changes are selective to the recovery of orthographic processing. To test our hypothesis, we examined longitudinal behavioral and functional magnetic resonance imaging (fMRI) data of reading, spelling, and visual object naming acquired acutely, 3 weeks, 5 months, and one year post stroke. In confirmation of our hypothesis, the loss and subsequent gain of orthographic lexical processing was associated with up-regulation of neural activation in areas previously associated with orthographic lexical processing: i.e., the left mid-FG and inferior frontal junction (IFJ). Furthermore, these neural changes were found to be selective to orthographic processing, as they were observed for reading and spelling, but not for visual object naming within the left mid-FG. This work shows that left PCA stroke can temporarily and selectively disrupt the orthographic lexical processing system, not only in the posterior region adjacent to the stroke, but also in relatively distant frontal orthographic processing regions.

Writing in the air: A visualization tool for written languages

The present study investigated interactions between cognitive processes and finger actions called “kusho,” meaning “air-writing” in Japanese. Kanji-culture individuals often employ kusho behavior in which they move their fingers as a substitute for a pen to write mostly done when they are trying to recall the shape of a Kanji character or the spelling of an English word. To further examine the visualization role of kusho behavior on cognitive processing, we conducted a Kanji construction task in which a stimulus (i.e., sub-parts to be constructed) was simultaneously presented. In addition, we conducted a Kanji vocabulary test to reveal the relation between the kusho benefit and vocabulary size. The experiment provided two sets of novel findings. First, executing kusho behavior improved task performance (correct responses) as long as the participants watched their finger movements while solving the task. This result supports the idea that visual feedback of kusho behavior helps cognitive processing for the task. Second, task performance was positively correlated with the vocabulary score when stimuli were presented for a relatively long time, whereas the kusho benefits and vocabulary score were not correlated regardless of stimulus-presentation time. These results imply that a longer stimulus-presentation could allow participants to utilize their lexical resources for solving the task. The current findings together support the visualization role of kusho behavior, adding experimental evidence supporting the view that there are interactions between cognition and motor behavior.

Shared orthographic neuronal representations for spelling and reading

A central question in the study of the neural basis of written language is whether reading and spelling utilize shared orthographic representations. While recent studies employing fMRI to test this question report that the left inferior frontal gyrus (IFG) and ventral occipitotemporal cortex (vOTC) are active during both spelling and reading in the same subjects (Purcell et al., 2011a; Rapp and Lipka, 2011), the spatial resolution of fMRI limits the interpretation of these findings. Specifically, it is unknown if the neurons which encode orthography for reading are also involved in spelling of the same words. Here we address this question by employing an event-related functional magnetic resonance imaging-adaptation (fMRI-A) paradigm designed to examine shared orthographic representations across spelling and reading. First, we identified areas that independently showed adaptation to reading, and adaptation to spelling. Then we identified spatial convergence for these two separate maps via a conjunction analysis. Consistent with previous studies (Purcell et al., 2011a; Rapp and Lipka, 2011), this analysis revealed the left dorsal IFG, vOTC and supplementary motor area. To further validate these observations, we then interrogated these regions using an across-task adaptation technique, and found adaptation across reading and spelling in the left dorsal IFG (BA 44/9). Our final analysis focused specifically on the Visual Word Form Area (VWFA) in the vOTC, whose variability in location among subjects requires the use of subject-specific identification mechanisms (Glezer and Riesenhuber, 2013). Using a functional localizer for reading, we defined the VWFA in each subject, and found adaptation effects for both within the spelling and reading conditions, respectively, as well as across spelling and reading. Because none of these effects were observed during a phonological/semantic control condition, we conclude that the left dorsal IFG and VWFA are involved in accessing the same orthography-specific representations for spelling and reading.

Idea units in notes and summaries for read texts by keyboard and pencil in middle childhood students with specific learning disabilities: Cognitive and brain findings

Seven children with dyslexia and/or dysgraphia (2 girls, 5 boys, M=11 years) completed fMRI connectivity scans before and after twelve weekly computerized lessons in strategies for reading source material, taking notes, and writing summaries by touch typing or groovy pencils. During brain scanning they completed two reading comprehension tasks-one involving single sentences and one involving multiple sentences. From before to after intervention, fMRI connectivity magnitude changed significantly during sentence level reading comprehension (from right angular gyrus→right Broca's) and during text level reading comprehension (from right angular gyrus→cingulate). Proportions of ideas units in children's writing compared to idea units in source texts did not differ across combinations of reading-writing tasks and modes. Yet, for handwriting/notes, correlations insignificant before the lessons became significant after the strategy instruction between proportion of idea units and brain connectivity at all levels of language in reading comprehension (word-, sentence-, and text) during scanning; but for handwriting/summaries, touch typing/notes, and touch typing/summaries changes in those correlations from insignificant to significant after strategy instruction occurred only at text level reading comprehension during scanning. Thus, handwriting during note-taking may benefit all levels of language during reading comprehension, whereas all other combinations of modes and writing tasks in this exploratory study appear to benefit only the text level of reading comprehension. Neurological and educational significance of the interdisciplinary research findings for integrating reading and writing and future research directions are discussed.

Neural Signatures of the Reading-Writing Connection: Greater Involvement of Writing in Chinese Reading than English Reading

Research on cross-linguistic comparisons of the neural correlates of reading has consistently found that the left middle frontal gyrus (MFG) is more involved in Chinese than in English. However, there is a lack of consensus on the interpretation of the language difference. Because this region has been found to be involved in writing, we hypothesize that reading Chinese characters involves this writing region to a greater degree because Chinese speakers learn to read by repeatedly writing the characters. To test this hypothesis, we recruited English L1 learners of Chinese, who performed a reading task and a writing task in each language. The English L1 sample had learned some Chinese characters through character-writing and others through phonological learning, allowing a test of writing-on-reading effect. We found that the left MFG was more activated in Chinese than English regardless of task, and more activated in writing than in reading regardless of language. Furthermore, we found that this region was more activated for reading Chinese characters learned by character-writing than those learned by phonological learning. A major conclusion is that writing regions are also activated in reading, and that this reading-writing connection is modulated by the learning experience. We replicated the main findings in a group of native Chinese speakers, which excluded the possibility that the language differences observed in the English L1 participants were due to different language proficiency level.

Neuroanatomy of Handwriting and Related Reading and Writing Skills in Adults and Children with and without Learning Disabilities: French-American Connections

In this article, we present recent neuroimaging studies performed to identify the neural network involved in handwriting. These studies, carried out in adults and in children, suggest that the mastery of handwriting is based on the involvement of a network of brain structures whose involvement and inter-connection are specific to writing alphabet characters. This network is built upon the joint learning of writing and reading and depends on the level of expertise of the writer. In addition, a part of this graphomotor network is also brought into play during the identification letters during visual reading. These skills are also the basis for the development of more complex language activities involving orthographic knowledge and composition of texts. The studies presented cover two perspectives: that of neuroscience and that of cognitive psychology, as both are necessary to understand a complex process of writing and both depend on natural interactions and the influence of educational exposure.

Disfluency effects on lexical selection

Recent research has suggested that introducing a disfluency in the context of written composition (i.e., typing with one hand) can increase lexical sophistication. In the current study, we provide a strong test between two accounts of this phenomenon, one that attributes it to the delay caused by the disfluency and one that attributes it to the disruption of typical finger-to-letter mappings caused by the disfluency. To test between these accounts, we slowed down participants' typewriting by introducing a small delay between keystrokes while individuals wrote essays. Critically, this manipulation did not disrupt typical finger-to-letter mappings. Consistent with the delay-based account, our results demonstrate that the essays written in this less fluent condition were more lexically diverse and used less frequent words. Implications for the temporal dynamics of lexical selection in complex cognitive tasks are discussed.

Response retrieval and motor planning during typing

Recent work in language production research suggests complex relationships between linguistic and motor processes. Typing is an interesting candidate for investigating further this issue. First, typing presumably relies on the same distributed left-lateralized brain network as handwriting and speech production. Second, typing has its own set of highly specific motor constraints, such as internal keystroke representations that hold information about both letter identity and spatial characteristics of the key to strike. The present study aims to further develop research on typed production, by targeting the dynamics between linguistic and motor neural networks. Specifically, we used a typed picture-naming task to examine the interplay between response retrieval and motor planning. To track processes associated with both linguistic processing and keystroke representation, we manipulated, respectively, the semantic context in which the target appeared and the side of the first keystrokes of the word. We recorded high-density electroencephalography (EEG) continuously from the presentation of a picture, to the typing of its name, and computed both event-related potentials (ERP) and beta-band power analyses. Non-parametric data-driven analysis revealed a clear pattern of response preparation over both hemispheres close to response time, in both the ERP and beta-band power modulations. This was preceded by a left-lateralized power decrease in the beta-band, presumably representing memory retrieval, and an early contrast in ERP, between left and right keystrokes' preparation. We discuss these results in terms of a dynamic access approach for internal keystroke representations, and argue for an integrative rather than separatist view of linguistic and motor processes.

The relations between reading and spelling: an examination of subtypes of reading disability

Three groups of reading-disabled children were found in studies of English, German, and French: a group with a double deficit in reading and spelling, a group with a single spelling deficit, and a more rarely reported group presenting a single reading deficit. This study set out to examine whether these groups can be found in adults, readers and spellers of Hebrew, which differs from the previously studied orthographies in many aspects. To this end, Hebrew-speaking adults with or without reading disability were administered various literacy and literacy-related tests. Results confirm the existence of the same three groups. While all shared a phonological deficit, subtle differences in phonological decoding ability and in speed of processing distinguished between the groups. The study therefore suggests that the previously reported associations and dissociations between reading and spelling are not restricted to English, German, or French and may not be only developmental in nature.

Neural bases of orthographic long-term memory and working memory in dysgraphia

Spelling a word involves the retrieval of information about the word's letters and their order from long-term memory as well as the maintenance and processing of this information by working memory in preparation for serial production by the motor system. While it is known that brain lesions may selectively affect orthographic long-term memory and working memory processes, relatively little is known about the neurotopographic distribution of the substrates that support these cognitive processes, or the lesions that give rise to the distinct forms of dysgraphia that affect these cognitive processes. To examine these issues, this study uses a voxel-based mapping approach to analyse the lesion distribution of 27 individuals with dysgraphia subsequent to stroke, who were identified on the basis of their behavioural profiles alone, as suffering from deficits only affecting either orthographic long-term or working memory, as well as six other individuals with deficits affecting both sets of processes. The findings provide, for the first time, clear evidence of substrates that selectively support orthographic long-term and working memory processes, with orthographic long-term memory deficits centred in either the left posterior inferior frontal region or left ventral temporal cortex, and orthographic working memory deficits primarily arising from lesions of the left parietal cortex centred on the intraparietal sulcus. These findings also contribute to our understanding of the relationship between the neural instantiation of written language processes and spoken language, working memory and other cognitive skills.

Contribution of writing to reading: Dissociation between cognitive and motor process in the left dorsal premotor cortex

Functional brain imaging studies reported activation of the left dorsal premotor cortex (PMd), that is, a main area in the writing network, in reading tasks. However, it remains unclear whether this area is causally relevant for written stimulus recognition or its activation simply results from a passive coactivation of reading and writing networks. Here, we used chronometric paired-pulse transcranial magnetic stimulation (TMS) to address this issue by disrupting the activity of the PMd, the so-called Exner's area, while participants performed a lexical decision task. Both words and pseudowords were presented in printed and handwritten characters. The latter was assumed to be closely associated with motor representations of handwriting gestures. We found that TMS over the PMd in relatively early time-windows, i.e., between 60 and 160 ms after the stimulus onset, increased reaction times to pseudoword without affecting word recognition. Interestingly, this result pattern was found for both printed and handwritten characters, that is, regardless of whether the characters evoked motor representations of writing actions. Our result showed that under some circumstances the activation of the PMd does not simply result from passive association between reading and writing networks but has a functional role in the reading process. At least, at an early stage of written stimuli recognition, this role seems to depend on a common sublexical and serial process underlying writing and pseudoword reading rather than on an implicit evocation of writing actions during reading as typically assumed.

Functional and anatomical dissociation between the orthographic lexicon and the orthographic buffer revealed in reading and writing Chinese characters by fMRI

The contribution of orthographic representations to reading and writing has been intensively investigated in the literature. However, the distinction between neuronal correlates of the orthographic lexicon and the orthographic (graphemic) buffer has rarely been examined in alphabetic languages and never been explored in non-alphabetic languages. To determine whether the neural networks associated with the orthographic lexicon and buffer of logographic materials are comparable to those reported in the literature, the present fMRI experiment manipulated frequency and the stroke number of Chinese characters in the tasks of form judgment and stroke judgment, which emphasized the processing of character recognition and writing, respectively. It was found that the left fusiform gyrus exhibited higher activation when encountering low-frequency than high-frequency characters in both tasks, which suggested this region to be the locus of the orthographic lexicon that represents the knowledge of character forms. On the other hand, the activations in the posterior part of the left middle frontal gyrus and in the left angular gyrus were parametrically modulated by the stroke number of target characters only in the stroke judgment task, which suggested these regions to be the locus of the orthographic buffer that represents the processing of stroke sequence in writing. These results provide the first evidence for the functional and anatomical dissociation between the orthographic lexicon and buffer in reading and writing Chinese characters. They also demonstrate the critical roles of the left fusiform area and the frontoparietal network to the long-term and short-term representations of orthographic knowledge, respectively, across different orthographies.

The Neural Basis of Typewriting: A Functional MRI Study

To investigate the neural substrate of typewriting Japanese words and to detect the difference between the neural substrate of typewriting and handwriting, we conducted a functional magnetic resonance imaging (fMRI) study in 16 healthy volunteers. All subjects were skillful touch typists and performed five tasks: a typing task, a writing task, a reading task, and two control tasks. Three brain regions were activated during both the typing and the writing tasks: the left superior parietal lobule, the left supramarginal gyrus, and the left premotor cortex close to Exner’s area. Although typing and writing involved common brain regions, direct comparison between the typing and the writing task revealed greater left posteromedial intraparietal cortex activation in the typing task. In addition, activity in the left premotor cortex was more rostral in the typing task than in the writing task. These findings suggest that, although the brain circuits involved in Japanese typewriting are almost the same as those involved in handwriting, there are brain regions that are specific for typewriting.

A preliminary fMRI study of a novel self-paced written fluency task: observation of left-hemispheric activation, and increased frontal activation in late vs. early task phases

Neuropsychological tests of verbal fluency are very widely used to characterize impaired cognitive function. For clinical neuroscience studies and potential medical applications, measuring the brain activity that underlies such tests with functional magnetic resonance imaging (fMRI) is of significant interest—but a challenging proposition because overt speech can cause signal artifacts, which tend to worsen as the duration of speech tasks becomes longer. In a novel approach, we present the group brain activity of 12 subjects who performed a self-paced written version of phonemic fluency using fMRI-compatible tablet technology that recorded responses and provided task-related feedback on a projection screen display, over long-duration task blocks (60 s). As predicted, we observed robust activation in the left anterior inferior and medial frontal gyri, consistent with previously reported results of verbal fluency tasks which established the role of these areas in strategic word retrieval. In addition, the number of words produced in the late phase (last 30 s) of written phonemic fluency was significantly less (p < 0.05) than the number produced in the early phase (first 30 s). Activation during the late phase vs. the early phase was also assessed from the first 20 s and last 20 s of task performance, which eliminated the possibility that the sluggish hemodynamic response from the early phase would affect the activation estimates of the late phase. The last 20 s produced greater activation maps covering extended areas in bilateral precuneus, cuneus, middle temporal gyrus, insula, middle frontal gyrus and cingulate gyrus. Among these areas, greater activation was observed in the bilateral middle frontal gyrus (Brodmann area BA 9) and cingulate gyrus (BA 24, 32) likely as part of the initiation, maintenance, and shifting of attentional resources. Consistent with previous pertinent fMRI literature involving overt and covert verbal responses, these findings highlight the promise and practicality of fMRI of written phonemic fluency.

Neuropsychological Profiles of Written Expression Learning Disabilities Determined by Concordance-Discordance Model Criteria

Children with specific learning disabilities (SLD) have disparate neuropsychological processing deficits that interfere with academic achievement in spelling, writing fluency, and/or written expression (WE). Although there are multiple potential causes of WE SLD, there is a paucity of research exploring this critical academic skill from a neuropsychological perspective. This study examined the neuropsychological profiles of WE SLD subtypes defined using the concordance-discordance model (C-DM) of SLD identification. Participants were drawn from a sample of 283 children (194 boys, 89 girls) aged 6 years to 16 years old (M(age) = 9.58 years, SD = 2.29 years) referred for comprehensive neuropsychological evaluations in school settings and subsequently selected based on C-DM determined spelling, writing fluency, and WE SLD. WE SLD subtypes differed on several psychomotor, memory, and executive function measures (F range = 2.48-5.07, p range = .049 to <.001), suggesting that these children exhibit distinct patterns of neuropsychological processing strengths and weaknesses. Findings have relevance for differential diagnosis of WE subtypes, discriminating WE SLD subtypes from low WE achievement, and developing differentiated evidence-based instruction and intervention for children with WE SLD. Limitations and future research will be addressed.

Accessing orthographic representations from speech: the role of left ventral occipitotemporal cortex in spelling

The present fMRI study used a spelling task to investigate the hypothesis that the left ventral occipitotemporal cortex (vOT) hosts neuronal representations of whole written words. Such an orthographic word lexicon is posited by cognitive dual‐route theories of reading and spelling. In the scanner, participants performed a spelling task in which they had to indicate if a visually presented letter is present in the written form of an auditorily presented word. The main experimental manipulation distinguished between an orthographic word spelling condition in which correct spelling decisions had to be based on orthographic whole‐word representations, a word spelling condition in which reliance on orthographic whole‐word representations was optional and a phonological pseudoword spelling condition in which no reliance on such representations was possible. To evaluate spelling‐specific activations the spelling conditions were contrasted with control conditions that also presented auditory words and pseudowords, but participants had to indicate if a visually presented letter corresponded to the gender of the speaker. We identified a left vOT cluster activated for the critical orthographic word spelling condition relative to both the control condition and the phonological pseudoword spelling condition. Our results suggest that activation of left vOT during spelling can be attributed to the retrieval of orthographic whole‐word representations and, thus, support the position that the left vOT potentially represents the neuronal equivalent of the cognitive orthographic word lexicon. Hum Brain Mapp, 36:1393–1406, 2015. © 2014 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Written language production disorders: historical and recent perspectives

Written language production is often the least examined neuropsychological function, yet it provides a sensitive and subtle sign to a variety of different behavioral disorders. The dissociation between written and spoken language and reading and writing first came to clinical prominence in the nineteenth century, with respect to ideas about localization of function. Twentieth century aphasiology research focused primarily on patients with unifocal lesions from cerebrovascular accidents, which have provided insight into the various levels of processing involved in the cognitively complex task of producing written language. Recent investigations have provided a broader perspective on writing impairments in a variety of disorders, including progressive and diffuse brain disorders, and functional brain imaging techniques have been used to study the underlying processes in healthy individuals.

Greater Utilization of Neural-Circuits Related to Executive Functions is Associated with Better Reading: A Longitudinal fMRI Study Using the Verb Generation Task

INTRODUCTION

Reading is an acquired-developmental ability that relies on intact language and executive function skills. Verbal fluency tasks (such as verb generation) also engage language and executive function skills. Performance of such tasks matures with normal language development, and is independent of reading proficiency. In this longitudinal fMRI study, we aim to examine the association between maturation of neural-circuits supporting both executive functions and language (assessed using verb generation) with reading proficiency achieved in adolescence with a focus on left-lateralization typical for language proficiency.

METHODS

Normalized fMRI data from the verb generation task was collected from 16 healthy children at ages 7, 11, and 17 years and was correlated with reading scores at 17 years of age. Lateralization indices were calculated in key language, reading, and executive function-related regions in all age groups.

RESULTS

Typical development was associated with (i) increasingly left-lateralized patterns in language regions (ii) more profound left-lateralized activation for reading and executive function-related regions when correlating with reading scores, (iii) greater involvement of frontal and parietal regions (in older children), and of the anterior frontal cortex (in younger children).

CONCLUSION

We suggest that reading and verb generation share mutual neural-circuits during development with major reliance on regions related to executive functions and reading. The results are discussed in the context of the dual-networks architecture model.

Beyond the visual word form area: the orthography-semantics interface in spelling and reading

Lexical orthographic information provides the basis for recovering the meanings of words in reading and for generating correct word spellings in writing. Research has provided evidence that an area of the left ventral temporal cortex, a subregion of what is often referred to as the visual word form area (VWFA), plays a significant role specifically in lexical orthographic processing. The current investigation goes beyond this previous work by examining the neurotopography of the interface of lexical orthography with semantics. We apply a novel lesion mapping approach with three individuals with acquired dysgraphia and dyslexia who suffered lesions to left ventral temporal cortex. To map cognitive processes to their neural substrates, this lesion mapping approach applies similar logical constraints to those used in cognitive neuropsychological research. Using this approach, this investigation: (a) identifies a region anterior to the VWFA that is important in the interface of orthographic information with semantics for reading and spelling; (b) determines that, within this orthography-semantics interface region (OSIR), access to orthography from semantics (spelling) is topographically distinct from access to semantics from orthography (reading); (c) provides evidence that, within this region, there is modality-specific access to and from lexical semantics for both spoken and written modalities, in both word production and comprehension. Overall, this study contributes to our understanding of the neural architecture at the lexical orthography-semantic-phonological interface within left ventral temporal cortex.