Dejerine's reading area revisited with intracranial EEG: Selective responses to letter strings

Université Pierre et Marie Curie University (M. Sharman), Paris
Neurology (Impact Factor: 8.29). 02/2013; 80(6):602-603. DOI: 10.1212/WNL.0b013e31828154d9
Source: PubMed


The visual word form area in the ventral occipitotemporal cortex develops with acquisition of reading skills. It is debated whether this region is specialized for reading(1) or is rather a general-purpose area associating visual form (words, objects) with meaning. An outline of this debate can be found in appendix e-1 on the Neurology® Web site at We recorded intracranial EEG in 2 patients with epilepsy (figures 1, e-1, and e-2) and found neural populations responding almost exclusively to letter strings, over 500% of all other responses. With the exception of the fusiform face area, such specific responses have never been described before in the human visual system.(2) Strong specialization in the human brain can thus be achieved also through cultural learning.

Download full-text


Available from: Carlos Hamamé, Oct 06, 2015
73 Reads
  • Source
    • "Finally, previous electrophysiological studies nicely demonstrated that the VOTC is activated at approximately 200 ms post word onset as can be evidenced both by ERPs (Nobre et al., 1994) and BG response (Hamame et al., 2013). This early activation in the VOTC fits well with the role of this region in processing pre-lexical and orthographic sensory input as demonstrated by fMRI (Levy et al., 2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Stimulus repetition can produce neural response attenuation in stimulus-category selective networks within the occipito-temporal lobe. It is hypothesized that this neural suppression reflects the functional sharpening of local neuronal assemblies which boosts information processing efficiency. This neural suppression phenomenon has been mainly reported during conditions of conscious stimulus perception. The question remains whether frequent stimuli processed in the absence of conscious perception also induce repetition suppression in those specialized networks. Using rare intracranial EEG recordings in the ventral occipito-temporal cortex (VOTC) of human epileptic patients we investigated neural repetition suppression in conditions of conscious and unconscious visual processing of words. To this end, we used an orthogonal design manipulating respectively stimulus repetition (frequent vs. unique stimuli) and conscious perception (masked vs. unmasked stimuli). By measuring the temporal dynamics of high-frequency broadband gamma activity in VOTC and testing for main and interaction effects, we report that early processing of words in word-form selective networks exhibits a temporal cascade of modulations by stimulus repetition and masking: neuronal attenuation initially is observed in response to repeated words (irrespective of consciousness), that is followed by a second modulation contingent upon word reportability (irrespective of stimulus repetition). Later on (>300ms post-stimulus), a significant effect of conscious perception on the extent of repetition suppression was observed. The temporal dynamics of consciousness, the recognition memory processes and their interaction revealed in this study advance our understanding of their contributions to the neural mechanisms of word processing in VOTC.
    NeuroImage 03/2014; 95. DOI:10.1016/j.neuroimage.2014.03.049 · 6.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The exact role of the left Ventral Occipito-Temporal Cortex (VOTC) during the initial stages of reading acquisition is a hotly debated issue, especially regarding the comparative effect of learning on early stimulus-dependent vs. later task-dependent processes. We show that this controversy can be solved with high-temporal resolution intracerebral EEG recordings of the VOTC. We measured High-Frequency Activity (50-150Hz) as a proxy of population-level spiking activity while participants learned Japanese Katakana symbols, and found that learning primarily affects top-down/task-dependent neural processing, after a few minutes only. In contrast, adaptation of early bottom-up/stimulus-dependent processing takes several days to adapt and provides the basis for fluent reading. Such evidence that two consecutive stages of neural processing, stimulus- and task-dependent are differentially affected by learning, can reconcile seemingly opposite hypotheses on the role of the VOTC during reading acquisition.
    NeuroImage 12/2013; 90. DOI:10.1016/j.neuroimage.2013.12.027 · 6.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Prior investigations of functional specialization have focused on the response profiles of particular brain regions. Given the growing emphasis on regional covariation, we propose to reframe these questions in terms of brain 'networks' (collections of regions jointly engaged by some mental process). Despite the challenges that investigations of the language network face, a network approach may prove useful in understanding the cognitive architecture of language. We propose that a language network plausibly includes a functionally specialized 'core' (brain regions that coactivate with each other during language processing) and a domain-general 'periphery' (a set of brain regions that may coactivate with the language core regions at some times but with other specialized systems at other times, depending on task demands). Framing the debate around network properties such as this may prove to be a more fruitful way to advance our understanding of the neurobiology of language.
    Trends in Cognitive Sciences 01/2014; 18(3). DOI:10.1016/j.tics.2013.12.006 · 21.97 Impact Factor
Show more