The dynamics of language-related high-gamma activity assessed on a spatially-normalized brain.
OBJECTIVE
We developed a novel technique of spatial normalization of subdural electrode positions across subjects and assessed the spatial-temporal dynamics of high-gamma activity (HGA) in the dominant hemisphere elicited by three distinct language tasks.


METHODS
The normalization process was applied to 1512 subdural electrodes implanted in 21 patients with intractable epilepsy. We projected each task-related HGA profile onto a normalized brain.


RESULTS
The word interpretation task initially elicited HGA augmentation in the bilateral fusiform gyri at 100 ms after stimulus onsets, subsequently in the left posterior middle temporal gyrus, in the left ventral premotor cortex at 200 ms and in the left middle and left inferior frontal gyri at 300 ms and after. The picture naming task elicited HGA augmentation in few sites in the left frontal lobe. The verb generation task elicited HGA in the left superior temporal gyrus at 100-600 ms. Common HGA augmentation elicited by all three tasks was noted in the left posterior-middle temporal and left ventral premotor cortices.


CONCLUSIONS
The spatial-temporal dynamics of language-related HGA were demonstrated on a spatially-normalized brain template.


CONCLUSIONS
This study externally validated the spatial and temporal dynamics of language processing suggested by previous neuroimaging and electrophysiological studies.
Department of Neurosurgery, The University of Tokyo, Tokyo, Japan.
Naoto
N
Kunii
Kyousuke
K
Kamada
Takahiro
T
Ota
Richard E
RE
Greenblatt
Kensuke
K
Kawai
Nobuhito
N
Saito
D000328:Adult; D000465:Algorithms; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003627:Data Interpretation, Statistical; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006801:Humans; D007802:Language; D007807:Language Tests; D008297:Male; D011578:Psycholinguistics; D012016:Reference Values; D013355:Subdural Space