Spectral Changes in Cortical Surface Potentials during Motor Movement

TLDR

The study quantified electrocorticographic changes during motor movement in 22 patients with subdural electrodes. Patients underwent 5–7 days of subdural monitoring and performed a motor‑repetition task, with spectral shifts in high‑ and low‑frequency bands mapped onto a Talairach‑standardized cortical template. Movement produced a decrease in low‑frequency power and an increase in high‑frequency power, with the high‑frequency changes being more focal and aligning with sensorimotor cortical sites and a classic somatotopic homunculus.

Abstract

In the first large study of its kind, we quantified changes in electrocorticographic signals associated with motor movement across 22 subjects with subdural electrode arrays placed for identification of seizure foci. Patients underwent a 5–7 d monitoring period with array placement, before seizure focus resection, and during this time they participated in the study. An interval-based motor-repetition task produced consistent and quantifiable spectral shifts that were mapped on a Talairach-standardized template cortex. Maps were created independently for a high-frequency band (HFB) (76–100 Hz) and a low-frequency band (LFB) (8–32 Hz) for several different movement modalities in each subject. The power in relevant electrodes consistently decreased in the LFB with movement, whereas the power in the HFB consistently increased. In addition, the HFB changes were more focal than the LFB changes. Sites of power changes corresponded to stereotactic locations in sensorimotor cortex and to the results of individual clinical electrical cortical mapping. Sensorimotor representation was found to be somatotopic, localized in stereotactic space to rolandic cortex, and typically followed the classic homunculus with limited extrarolandic representation.