 The overall goal of this study is to preliminarily evaluate an improved recording strategy and analytical techniques to better define SD events and structural abnormalities in the severely injured brain that produce these CSD events in severe TBI. In order to achieve this goal, this study will utilize 4 subdural electrode strips arranged to produce a 4x4 grid of electrode contacts for the recording of ECoG activity in conjunction with simultaneous acquisition of several other physiological measures in TBI patients requiring neurosurgical intervention. 