AEPs

Auditory evoked potentials (AEPs) are electrical responses generated by the auditory nervous system in reaction to sound. They are recorded noninvasively from the scalp or ear canal using surface electrodes and reflect the sequential activation of auditory pathways from the cochlea to the cortex. AEPs are typically measured by averaging responses over many stimulus presentations to improve signal-to-noise ratio.

AEPs are commonly categorized by their latency (timing after the stimulus). Brainstem auditory evoked potentials (BAEPs or ABRs) occur within the first 10 milliseconds and include waves I through V that correspond to activity in the auditory nerve and brainstem nuclei. Middle-latency responses (MLRs) occur roughly from 12 to 50 milliseconds and reflect thalamic and early cortical processing. Late or cortical AEPs include components such as N1 and P2 (approximately 80 to 200 milliseconds) and the P300 (around 300 milliseconds), which are associated with attention, discrimination, and higher-level cognitive processing. The mismatch negativity (MMN) is another cortical response elicited by deviant sounds in a sequence and is often considered part of the AEP family in cognitive research.

Applications of AEPs include objective assessment of hearing in individuals who cannot provide behavioral responses (e.g., newborns or uncooperative patients), evaluation of auditory pathway integrity (including retrocochlear pathology), intraoperative monitoring during brain or auditory nerve procedures, and research into auditory perception, attention, and cognitive processing. Recording requires controlled stimuli, proper electrode placement, and artifact management; results can be influenced by factors such as state of arousal, medication, and technical setup.