CE37 - Neurosciences intégratives et cognitives

Origins of the specialization for reading in the occipitotemporal cortex – TOPLEX

In WP1, we will study those predictions using brain imaging in normal subjects. Using 3T fMRI, we will first prove that all of these factors can affect VOT activity. Using MEG and source analysis, we will probe the latency with which they do. Finally, we will use 7T fMRI to increase resolution in the cortical plane and to attempt to reach laminar resolution across cortical layers, thus separating the predominantly bottom-up inputs to layer IV and the top-down influences to supra- and infra-granular layers 22. Although challenging, there is now evidence that it is possible to reach laminar resolution with 7 Tesla fMRI, including in the VWFA 23-26.
In WP2, we will test the causality of top-down influences using brain-imaging in brain-damaged patients. The unique contribution of neuropsychological data is to allow us to determine the causal involvement of distant regions on reading-related properties of the VOT, which the imaging methods cannot provide. For instance, assuming that sensitivity of the VOT to word frequency originates in perisylvian language areas, the effect should be obliterated in patients with lesions in the source area. If however, this effect is bottom-up, it should remain in the VWFA even in severely aphasic patients.
In WP3, we will develop models of the interaction of bottom-up and top-down influences on the development and functioning of the VWFA. We will use variants of CORNET, a convolutional neural network whose properties are thought to tightly match those of the primate visual system for object recognition27-29. We will study how this network, usually used for image identification, changes with reading acquisition. We will probe to what extent a purely bottom-up model can mimic the effect of the above factors, then examine whether and how top-down connectivity must be introduced.

Work in progress

Development of the ongoing project

Cohen, Laurent, Philippine Salondy, Christophe Pallier, and Stanislas Dehaene. “How Does Inattention Affect Written and Spoken Language Processing?” Cortex 138 (May 2021): 212–27. doi.org/10.1016/j.cortex.2021.02.007.

Zhan, Minye, Pallier, Christophe, Dehaene, Stanislas, and Cohen, Laurent. “Does the Visual Word Form Area Split in Bilingual Readers? A Millimeter-Scale 7T FMRI Study,” In preparation

Hauw, Fabien, Mohamed El Soudany, Charlotte Rosso, Jean Daunizeau, and Laurent Cohen. “Seeing Speech: The Cerebral Substrate of Tickertape Synesthesia,” Submitted.

Hauw, Fabien, Mohamed El Soudany, and Laurent Cohen. “Subtitled Speech: Phenomenology of Tickertape Synesthesia,” Submitted.

Hannagan, T., A. Agrawal, L. Cohen, and S. Dehaene. “Emergence of a Compositional Neural Code for Written Words: Recycling of a Convolutional Neural Network for Reading.” Proceedings of the National Academy of Sciences 118, no. 46 (November 16, 2021): e2104779118. doi.org/10.1073/pnas.2104779118.

Submission summary

The left ventral occipitotemporal cortex plays a key role in word reading. Brain imaging revealed that this ability rests on a reproducible patch of cortex along the left fusiform gyrus, the Visual Word Form Area (VWFA), which shows functional specialization for word perception. It is unknown whether the reading-specific properties of the VWFA result from bottom-up (BU) input from low-level visual areas, or from top-down (TD) influences from areas involved in phonology and semantics. The goal of the TOPLEX project is to disentangle the role of BU and TD input through 3 workpackages. We will (i) study brain activations of the VWFA in healthy subjects with 7 Tesla fMRI, while manipulating BU and TD input to the VWFA; (ii) study activation of the VWFA in stroke patients with remote lesions disrupting the TD input to the VWFA; (iii) use neural networks to model the interaction of BU and TD influences on the development and functioning of the VWFA.

Project coordination

Laurent Cohen (INSTITUT DU CERVEAU MOELLE EPINIERE)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ICM INSTITUT DU CERVEAU MOELLE EPINIERE
JOLIOT Institut des sciences du vivant FRÉDÉRIC-JOLIOT

Help of the ANR 443,349 euros
Beginning and duration of the scientific project: January 2021 - 36 Months

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