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Proc Natl Acad Sci U S A. 2016 Jul 19;113(29):8162-7. doi: 10.1073/pnas.1604126113. Epub 2016 Jun 20.

Decoding and disrupting left midfusiform gyrus activity during word reading.

Author information

1
Learning Research and Development Center, University of Pittsburgh, Pittsburgh, PA 15260; hirshorn@pitt.edu.
2
Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15260; Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh, Pittsburgh, PA 15213; Program in Neural Computation, Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh, Pittsburgh, PA 15213;
3
Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15260;
4
Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15260; Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh, Pittsburgh, PA 15213;
5
Learning Research and Development Center, University of Pittsburgh, Pittsburgh, PA 15260; Center for the Neural Basis of Cognition, Carnegie Mellon University and University of Pittsburgh, Pittsburgh, PA 15213; Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15260.

Abstract

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.

KEYWORDS:

electrical stimulation; fusiform gyrus; intracranial EEG; temporal dynamics; word reading

Comment in

PMID:
27325763
PMCID:
PMC4961146
DOI:
10.1073/pnas.1604126113
[Indexed for MEDLINE]
Free PMC Article

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