Abstracts

Rationale: To determine if behavioral states can be shown to exhibit unique spatial EEG when recorded with a microgrid array applied to the cortical surface. Methods: A 34 year old woman with intractable epilepsy underwent intracranial EEG monitoring after standard methods failed to reveal localization of seizures. During the 8 day period of invasive recording, in addition to standard clinical electrodes, a cm2 microgrid array, consisting of 8x8 electrodes was placed over the right inferior temporal gyrus. Careful review of video recordings identified four extended naturalistic behaviors: reading, conversing on the telephone, looking at photographs, and face-to-face interactions. EEG activity recorded with the microgrid and corresponding to these behaviors was collected and electrographic spatial patterns were analyzed. During periods of EEG selected for analysis, no electrographic seizures or epileptiform patterns were present. Moments of maximal spatial variance were entered into a principal component analysis, with results plotted on a 3-D scatter-gram for each condition. Results: The first 3 principal components are clustered by behavior (Figure 1). Between condition comparisons using a permutation test reveal significantly different spatial patterns for each behavior. Conclusions: With optimal spatial resolution, EEG recordings obtained on the cortical surface may reveal distinct local spatial patterns that reflect different behavioral states