A compositional letter code in high-level visual cortex explains how we read jumbled words

ABSTRACTWe read words and even jubmled wrods effortlessly, but the neural representations underlying this remarkable ability remain unknown. We hypothesized that word processing is driven by a visual representation that is compositional i.e. with string responses systematically related to letters. To test this hypothesis, we devised a model in which neurons tuned to letter shape respond to longer strings by linearly summing letter responses. This letter model explained human performance in both visual search as well as word reading tasks. Brain imaging revealed that viewing a string activates this compositional letter code in the lateral occipital (LO) region, and that subsequent comparisons to known words are computed by the visual word form area (VWFA). Thus, seeing a word activates a compositional letter code that enables efficient reading.

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A compositional neural code in high-level visual cortex can explain jumbled word reading

eLife ◽

10.7554/elife.54846 ◽

2020 ◽

Vol 9 ◽

Author(s):

Aakash Agrawal ◽

KVS Hari ◽

SP Arun

Keyword(s):

Visual Search ◽

Human Performance ◽

Word Reading ◽

Neural Correlates ◽

Neural Code ◽

Word Form ◽

Visual Model ◽

Visual Word Form Area ◽

High Level ◽

Letter Shape

We read jubmled wrods effortlessly, but the neural correlates of this remarkable ability remain poorly understood. We hypothesized that viewing a jumbled word activates a visual representation that is compared to known words. To test this hypothesis, we devised a purely visual model in which neurons tuned to letter shape respond to longer strings in a compositional manner by linearly summing letter responses. We found that dissimilarities between letter strings in this model can explain human performance on visual search, and responses to jumbled words in word reading tasks. Brain imaging revealed that viewing a string activates this letter-based code in the lateral occipital (LO) region and that subsequent comparisons to stored words are consistent with activations of the visual word form area (VWFA). Thus, a compositional neural code potentially contributes to efficient reading.

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Visual word form processing deficits driven by severity of reading impairments in children with developmental dyslexia

Scientific Reports ◽

10.1038/s41598-020-75111-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

S. Brem ◽

U. Maurer ◽

M. Kronbichler ◽

M. Schurz ◽

F. Richlan ◽

...

Keyword(s):

Reading Fluency ◽

Word Processing ◽

Visual Word ◽

Common Finding ◽

Word Form ◽

Reduced Word ◽

Form Processing ◽

Visual Word Form Area ◽

Intermediate Readers ◽

Spatially Extended

Abstract The visual word form area (VWFA) in the left ventral occipito-temporal (vOT) cortex is key to fluent reading in children and adults. Diminished VWFA activation during print processing tasks is a common finding in subjects with severe reading problems. Here, we report fMRI data from a multicentre study with 140 children in primary school (7.9–12.2 years; 55 children with dyslexia, 73 typical readers, 12 intermediate readers). All performed a semantic task on visually presented words and a matched control task on symbol strings. With this large group of children, including the entire spectrum from severely impaired to highly fluent readers, we aimed to clarify the association of reading fluency and left vOT activation during visual word processing. The results of this study confirm reduced word-sensitive activation within the left vOT in children with dyslexia. Interestingly, the association of reading skills and left vOT activation was especially strong and spatially extended in children with dyslexia. Thus, deficits in basic visual word form processing increase with the severity of reading disability but seem only weakly associated with fluency within the typical reading range suggesting a linear dependence of reading scores with VFWA activation only in the poorest readers.

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White matter disconnectivity fingerprints causally linked to dissociated forms of alexia

Communications Biology ◽

10.1038/s42003-021-02943-z ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Sam Ng ◽

Sylvie Moritz-Gasser ◽

Anne-Laure Lemaitre ◽

Hugues Duffau ◽

Guillaume Herbet

Keyword(s):

Word Reading ◽

Population Based ◽

Neural System ◽

Word Form ◽

Pure Alexia ◽

Visual Word Form Area ◽

Neurosurgical Patients ◽

Streamline Tractography ◽

Models Of Reading

AbstractFor over 150 years, the study of patients with acquired alexia has fueled research aimed at disentangling the neural system critical for reading. An unreached goal, however, relates to the determination of the fiber pathways that root the different visual and linguistic processes needed for accurate word reading. In a unique series of neurosurgical patients with a tumor close to the visual word form area, we combine direct electrostimulation and population-based streamline tractography to map the disconnectivity fingerprints characterizing dissociated forms of alexia. Comprehensive analyses of disconnectivity matrices establish similarities and dissimilarities in the disconnection patterns associated with pure, phonological and lexical-semantic alexia. While disconnections of the inferior longitudinal and posterior arcuate fasciculi are common to all alexia subtypes, disconnections of the long arcuate and vertical occipital fasciculi are specific to phonological and pure alexia, respectively. These findings provide a strong anatomical background for cognitive and neurocomputational models of reading.

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Decoding and disrupting left midfusiform gyrus activity during word reading

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1604126113 ◽

2016 ◽

Vol 113 (29) ◽

pp. 8162-8167 ◽

Cited By ~ 47

Author(s):

Elizabeth A. Hirshorn ◽

Yuanning Li ◽

Michael J. Ward ◽

R. Mark Richardson ◽

Julie A. Fiez ◽

...

Keyword(s):

Word Processing ◽

Word Reading ◽

Early Stage ◽

Visual Representation ◽

Strong Support ◽

Visual Word ◽

Word Form ◽

Word Forms ◽

Precise Representation ◽

Intracranial Electroencephalography

The nature of the visual representation for words has been fiercely debated for over 150 y. We used direct brain stimulation, pre- and postsurgical behavioral measures, and intracranial electroencephalography to provide support for, and elaborate upon, the visual word form hypothesis. This hypothesis states that activity in the left midfusiform gyrus (lmFG) reflects visually organized information about words and word parts. In patients with electrodes placed directly in their lmFG, we found that disrupting lmFG activity through stimulation, and later surgical resection in one of the patients, led to impaired perception of whole words and letters. Furthermore, using machine-learning methods to analyze the electrophysiological data from these electrodes, we found that information contained in early lmFG activity was consistent with an orthographic similarity space. Finally, the lmFG contributed to at least two distinguishable stages of word processing, an early stage that reflects gist-level visual representation sensitive to orthographic statistics, and a later stage that reflects more precise representation sufficient for the individuation of orthographic word forms. These results provide strong support for the visual word form hypothesis and demonstrate that across time the lmFG is involved in multiple stages of orthographic representation.

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Considering unique, shared, and dominant brain activation in the Visual Word Form Area and Lateral Occipital Cortex: A comparison of separate and combined word reading and picture naming

10.1101/2021.09.20.461111 ◽

2021 ◽

Author(s):

Josh Neudorf ◽

Layla Gould ◽

Marla J. S. Mickleborough ◽

Chelsea Ekstrand ◽

Ron Borowsky

Keyword(s):

Picture Naming ◽

Word Reading ◽

Visual Complexity ◽

Occipital Cortex ◽

Visual Word ◽

Word Form ◽

Lateral Occipital Complex ◽

Visual Word Form Area ◽

The Right ◽

Lateral Occipital Cortex

Identifying printed words and pictures concurrently is ubiquitous in daily tasks, and so it is important to consider the extent to which reading words and naming pictures may share a cognitive-neurophysiological functional architecture. Two functional magnetic resonance imaging (fMRI) experiments examined whether reading along the left ventral occipitotemporal region (vOT; often referred to as a visual word form area, VWFA) has activation that is overlapping with referent pictures (i.e., both conditions significant and shared, or with one significantly more dominant) or unique (i.e., one condition significant, the other not), and whether picture naming along the right lateral occipital complex (LOC) has overlapping or unique activation relative to referent words. Experiment 1 used familiar regular and exception words (to force lexical reading) and their corresponding pictures in separate naming blocks, and showed dominant activation for pictures in the LOC, and shared activation in the VWFA for exception words and their corresponding pictures (regular words did not elicit significant VWFA activation). Experiment 2 controlled for visual complexity by superimposing the words and pictures and instructing participants to either name the word or the picture, and showed primarily shared activation in the VWFA and LOC regions for both word reading and picture naming, with some dominant activation for pictures in the LOC. Overall, these results highlight the importance of including exception words to force lexical reading when comparing to picture naming, and the significant shared activation in VWFA and LOC serves to challenge specialized models of reading or picture naming.

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Word and non-word reading: What role for the Visual Word Form Area?

NeuroImage ◽

10.1016/j.neuroimage.2005.04.038 ◽

2005 ◽

Vol 27 (3) ◽

pp. 694-705 ◽

Cited By ~ 107

Author(s):

M. Vigneau ◽

G. Jobard ◽

B. Mazoyer ◽

N. Tzourio-Mazoyer

Keyword(s):

Word Reading ◽

Visual Word ◽

Word Form ◽

Visual Word Form Area

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High-level Integrative Networks: A Resting-state fMRI Investigation of Reading and Spelling

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01405 ◽

2019 ◽

Vol 31 (7) ◽

pp. 961-977 ◽

Cited By ~ 1

Author(s):

Gali Ellenblum ◽

Jeremy J. Purcell ◽

Xiaowei Song ◽

Brenda Rapp

Keyword(s):

Resting State ◽

Resting State Fmri ◽

Visual Word ◽

Orthographic Processing ◽

Word Form ◽

Visual Word Form Area ◽

Reference Networks ◽

High Level ◽

Reading And Spelling ◽

Processing Networks

Orthographic processing skills (reading and spelling) are evolutionarily recent and mastered late in development, providing an opportunity to investigate how the properties of the neural networks supporting skills of this type compare to those supporting evolutionarily older, well-established “reference” networks. Although there has been extensive research using task-based fMRI to study the neural substrates of reading, there has been very little using resting-state fMRI to examine the properties of orthographic networks. In this investigation using resting-state fMRI, we compare the within-network and across-network coherence properties of reading and spelling networks directly to these properties of reference networks, and we also compare the network properties of the key node of the orthographic networks—the visual word form area—to those of the other nodes of the orthographic and reference networks. Consistent with previous results, we find that orthographic processing networks do not exhibit certain basic network coherence properties displayed by other networks. However, we identify novel distinctive properties of the orthographic processing networks and establish that the visual word form area has unusually high levels of connectivity with a broad range of brain areas. These characteristics form the basis of our proposal that orthographic networks represent a class of “high-level integrative networks” with distinctive properties that allow them to recruit and integrate multiple, lower level processes.

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