Decoding and disrupting left midfusiform gyrus activity during word reading.
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.
Learning Research and Development Center, University of Pittsburgh, Pittsburgh, PA 15260; hirshorn@pitt.edu.
Elizabeth A
EA
Hirshorn
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;
Yuanning
0000-0003-3277-0600
Y
Li
Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15260;
Michael J
MJ
Ward
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;
R Mark
0000-0003-2620-7387
RM
Richardson
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.
Julie A
JA
Fiez
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;
Avniel Singh
AS
Ghuman
D000328:Adult; D046690:Deep Brain Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000502:physiology*; D011932:Reading; D013702:Temporal Lobe / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
electrical stimulation; fusiform gyrus; intracranial EEG; temporal dynamics; word reading