Invasive electrophysiology offers a unique opportunity to record both the single-cell and population activity of neurons surrounding the depth electrode in a specific target area. Leveraging such direct access to subcortical regions, human and animal research has provided valuable insight into the mechanisms underlying the functional alterations of neural processing associated with Parkinson’s disease and inspired the advent of adaptive deep brain stimulation techniques. This chapter introduces the available methods for acquiring invasive electrophysiological signals and discusses recent findings about disease-related alterations from a frequency-specific perspective.