Spectral Changes in Motor Thalamus Field Potentials during Movement

The motor thalamus plays a crucial role in the integration and modulation of sensorimotor information and projects to the primary motor cortex. While voltage power spectral changes in the motor cortex with movement have been well-characterized, the corresponding activity in the motor thalamus, particularly broadband (sometimes referred to as high gamma) power, remains unclear. The present study aims to characterize spectral changes in the motor thalamus during hand movements of 15 subjects undergoing awake deep brain stimulation surgery targeting the ventral intermediate (VIM) nucleus of the thalamus for disabling tremor. We analyzed power changes in subject-specific low frequency oscillations (<30 Hz) and broadband power (captured in 65-115 Hz band) of serial field potential recordings. Consistent with previous studies, we found widespread decreases in low-frequency oscillations with movement. Importantly, in most subjects we also observed a significant increase in broadband power, primarily in the inferior recording sites corresponding with estimated VIM region. One subject also performed an imagined movement task during which low frequency oscillatory power was suppressed. These electrophysiologic changes may be leveraged as biomarkers for thalamic functional mapping, DBS targeting, and closed loop applications.