Abstracts

Rationale: Cognitive flexibility is involved in the process of adapting to changing circumstances and is often assessed by neuropsychologists, using a task requiring switching from one goal to another. Previous studies have suggested an association between frontal lobe damage and impaired performance on tasks measuring cognitive flexibility. Few investigators have attempted to localize the cortical region exerting cognitive flexibility for children undergoing epilepsy surgery. Here, we explored if measurement of event-related high-gamma activity on extraoperative electrocorticography (ECoG) during a game play session can localize the cortical sites involved in cognitive flexibility. Methods: Chronic ECoG recording was performed as part of routine procedures for localization of the epileptogenic zone and eloquent areas. High-gamma activity at 70-110 Hz was measured during five sessions of 1-min game play (Lumosity; Lumos Labs, Inc, San Francisco, CA). 'Ebb and Flow' was chosen as the game, in which users are presented either green or orange leaves moving across a pond, and have to swipe in the direction of where green leaves are pointing or orange leaves are moving. Color and direction of leaves were changed across trials in an unpredictable manner. We determined the spatial-temporal pattern of high-gamma modulation immediately after task switch as well as during patient's swiping response. Results: Task switch (i.e.: changing the color of leaves), in general, elicited larger high-gamma augmentation at the ventral visual pathway at 50-350 ms after task-switch onset. Furthermore, task switch specifically from green- to orange-leave trials elicited high-gamma augmentation in the caudal middle-frontal gyrus at 0-400 ms after task-switch onset. Finger swiping was associated with high-gamma augmentation in the pre- and post-central gyri at the level of hand sensorimotor area. Conclusions: Measurement of high-gamma modulation related to task switching is feasible in presurgical evaluation of pediatric population. The caudal middle-frontal gyrus showing high-gamma augmentation specifically associated with task switch in a green-to-orange direction may be involved in selective attention to visual motion. Further studies are warranted to determine the clinical utility of our brain mapping method to predict behavioral outcomes following pediatric epilepsy surgery. Funding: R01NS064033 to E. Asano.