Aperiodic activity distinguishes cortical and subcortical signals

Alan Bush and colleagues examined the aperiodic “1/f” component of local field potentials — the broadband part of the signal often discarded as background — recorded from cortex, basal ganglia, and thalamus in movement-disorder and epilepsy patients. Refining a widely used model for extracting aperiodic parameters, they found the cortical aperiodic exponent was higher in Parkinson’s patients with more severe motor symptoms, suggesting a potential electrophysiological biomarker. Strikingly, subcortical structures — thalamus, pallidum, and subthalamic nucleus — showed a consistently lower exponent and no aperiodic “knee,” a pattern replicated in epilepsy patients that may reflect cytoarchitectonic and functional differences. The work shows the aperiodic signal carries meaningful, region-specific information rather than mere noise.