Event-related brain potential investigations of memory and aging.

A review of the literature that examines event-related brain potentials (ERPs) and memory with respect to aging reveals some consistency in the processes that might be spared and those that might be compromised with increasing age. By and large, the ERP repetition effect, recorded during indirect memory paradigms, appears to be relatively intact with aging, suggesting spared repetition priming mechanisms and the brain substrates upon which they depend. Some age-related findings during direct (i.e. explicit) memory testing suggest that a left-sided posterior old/new effect ( approximately 500-800 ms), thought to reflect a relatively automatic retrieval of item information, is equivalent in young and old. A later, long-duration, right-sided, prefrontal old/new effect, allied with the search for and/or the retrieval of contextual information (i.e. source memory), has been found to be smaller or absent in the waveforms of the old in two of three studies, suggesting impaired source memory mechanisms in the elderly. It is argued that the data are relatively consistent with spared item retrieval mechanisms in the elderly presumably supported by medial temporal lobe structures. However, although the data are suggestive, there are too few studies at this time to reach a firm conclusion as to whether the mechanisms that support contextual retrieval, presumably mediated by prefrontal cortical structures, are impaired in the elderly.