Within- and Between- Channel Gaps Elicit Mismatch Negativity in the Aging Brain

Objective: This study examined how older and younger adults process silent gaps in auditory stimuli by recording cortical evoked potentials using a multi-deviant paradigm that is compared to a psychophysical gap-detection task. Design: Participants passively listened to pairs of noise markers separated by silent intervals. Markers were either spectrally identical (within-channel) or spectrally distinct (between-channel) narrowband noises. Seven gap durations served as deviants in a multi-deviant sequence. The deviance-related negativity (DRN) and the P2/P3a were recorded from fronto-central electrodes. Study Sample: Thirty-two subjects with normal hearing or minimal hearing loss participated in this study. They were separated into an older adult (mean age = 63 years) and younger adults (mean age = 24 years) group. Results: Gapped deviants significantly enhanced DRN amplitude in both within- and between-channel conditions. Age effects emerged in the peak-to-peak DRN-P2/P3a measure. Older adults showed a longer DRN latency compared to the younger group, but no condition effects. In contrast, the younger group had longer latencies in the between-channel condition only. P2/P3a responses did not show any condition or age-specific effects. Behavioral gap-detection thresholds did not differ across conditions in older adults. Conclusions: Overall, results demonstrate that electrophysiological indices provide a more sensitive marker of age-related auditory changes, revealing subtle neural alterations in temporal resolution that may precede behavioral decline.