Event-related brain potentials (ERPs) and behavioral indices will be recorded from subjects in 3 age groups (20-30; 45-55; 65-80), free of dementia, depression, health problems and problems with activities of daily living. Converging evidence from ERP and behavioral studies, as well as amnesia, suggest that performance on tasks which do (explicit memory) and do not (implicit memory) require the conscious recollection of items stored in memory reflect cognitively distinct systems and, further, that their underlying brain mechanisms may also be distinct. This proposal is an attempt to begin to apply these findings in order to better understand age-related differences in memory function. Additional experiments are included in order to elucidate the change with age in the scalp distribution of """"""""P300."""""""" Each of the memory experiments includes a study phase, with subsequent implicit and/or explicit memory testing of those items presented during the study series. In this fashion, ERPs and behavior can be compared among age groups, between implicit and explicit memory, and for the interaction of age and type of memory. Hypotheses to be tested are: 1) Behavioral measures of implicit and explicit memory will be relatively independent, and may be associated with different ERP components, manifested by changes in scalp distribution; 2) In general, the elderly will be relatively intact on both ERP and behavioral correlates of implicit relative to explicit memory; 3) Age Group and Encoding Task will not interact for implicit measures, but will for ERP and behavioral measures of explicit memory; 4) For newly learned associations, ERP and behavioral priming will occur for all age groups, although the elderly relative to the younger adults will show ERP and behavioral differences in recognition and recall of those newly learned associations; 5) """"""""Obligatory P300"""""""" to intense auditory stimuli will show the shift in topography with age similar to that shown by classical """"""""P300."""""""" These data will have application to brain models of normal aging as well as for deviant aging, e.g., Alzheimer's disease, in which memory dysfunction is a consequence of deterioration in brain function.
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