UC Irvine

Here we investigate high frequency activity (HFA) evoked during face perception in humans. The purpose of this research are: (1) to develop and validate an automatic HFA detector, (2) to determine whether HFA is increased during face processing, and (3) to compare the characteristics of HFAs between baseline and activation conditions.

Twelve subjects undergoing clinical evaluation for epilepsy surgery passively viewed a paradigm to activate face-sensitive regions in the brain. The paradigm consisted of alternating 24-second blocks of baseline (landscapes) and activation (faces) video clips for a total of 16 blocks. Target locations for the implanted electrodes were determined solely for the purpose of seizure localization. A total of 465 bipolar signals were analyzed after excluding electrodes within the seizure onset zone and anatomical defects and those having excessive noise. We compared the rate of HFAs during viewing of landscapes versus faces. In 14 sites across four subjects, we found a significant increase in HFA rates during face viewing. Some sites corresponded to regions previously associated with face processing while additional sites were located in frontal regions. These findings may provide important information about the activity of brain regions during face processing that cannot be inferred from phase-locked ERPs.