Cortical event-related potentials (ERPs) show a reduction in amplitude when the stimulus is self-produced vs. listened to, a phenomenon known as movement or speech-induced suppression (SIS). The suppression effect appears to be linked to sensorimotor predictive or comparative processes. The degree of suppression does not appear to be as strong in individuals with certain neurological disorders, such as Parkinson’s disease.

Cortical event-related potentials (ERPs) are recorded using a Biosemi system with 64 channels. Speech is recorded using a head-mounted microphone to maintain a consistent mouth-to-microphone distance. Audio is presented with Etymotic ER2 insert earphones. Data are collected using Biosemi’s ActiveTwo system, then transferred to Matlab for post-processing. The lab currently uses Eeglab along with custom programs to automatize certain steps in the signal processing procedure.

The Biosemi module is equipped with an ABR module for brainstem evoked-response recording.