Auditory evoked MEG responses to interaural phase changes: Effects of aging on response latencies

The ability to perceive time-varying acoustic changes deteriorates with advancing age. To learn more about the mechanisms underlying such perceptual deficits, we used magnetoencephalography (MEG) to examine the physiological response to interaural phase differences (IPD) in young, middle-aged, and older adults. Stimulus onset evoked P1m–N1m–P2m cortical responses, as did the change in interaural phase. There were no significant age-related latency differences in the detection of sound “onset”; however, the ability to detect “changes” within the stimulus deteriorated with increased age. Peak latencies were prolonged for the “change” response when compared to the “onset” response, suggesting that the physiological detection of IPDs requires more time than detecting sound “onset”. These results provide physiological evidence of impaired temporal processing in the elderly that is likely unrelated to hearing loss or cognitive ability because brain activity was measured passively in response to audible low frequency stimuli.