High frequency activation data used to validate localization of cortical electrodes during surgery for deep brain stimulation

Movement related synchronization of high frequency activity (HFA, 76–100 Hz) is a somatotopic process with spectral power changes occurring during movement in the sensorimotor cortex (Miller et al., 2007) [1]. These features allowed movement-related changes in HFA to be used to functionally validate the estimations of subdural electrode locations, which may be placed temporarily for research in deep brain stimulation surgery, using the novel tool described in Randazzo et al. (2015) [2]. We recorded electrocorticography (ECoG) signals and localized electrodes in the region of the sensorimotor cortex during an externally cued hand grip task in 8 subjects. Movement related HFA was determined for each trial by comparing HFA spectral power during movement epochs to pre-movement baseline epochs. Significant movement related HFA was found to be focal in time and space, occurring only during movement and only in a subset of electrodes localized to the pre- and post-central gyri near the hand knob. To further demonstrate the use of movement related HFA to aid electrode localization, we provide a sample of the electrode localization tool, with data loaded to allow readers to map movement related HFA onto the cortical surface of a sample patient.