Lack of standard N2 in elderly participants indicates inhibitory processing deficit.

We analyzed the cortical responses to standard stimuli presented in an auditory oddball paradigm from two groups of young and elderly participants in unattended and attended conditions. A sustained negativity (N2) followed N1 and P2 in the responses of the young participants. This negativity was reduced or absent in the elderly. With attention, the early portion of N2 (N2early) decreased in both groups, whereas the late portion (N2late) increased only in young participants. We suggest inhibitory processes at the origin of this component. The lack of N2 in the elderly participants is consistent with structural changes in the aging brain and supports the hypothesis of a specific age-related deficit in the inhibition of irrelevant information processing.