EXPLICIT AND IMPLICIT MEMORY IN THE ELDERLY - EVIDENCE FOR DOUBLE DISSOCIATION INVOLVING MEDIAL TEMPORAL-LOBE AND FRONTAL-LOBE FUNCTIONS

Groups of normal old people living in institutions or in the community and young adults were administered tests of implicit (IM) and explici t (EM) memory with word-stem (WSC) and word-fragment (WFC) completion paradigms. Neuropsychological tests sensitive to frontal and medial te mporal lobe function were also administered. Age differences were obse rved on both tests of EM and on all neuropsychological tests. Priming effects on WSC were smaller in the institutionalized group than the ot her 2 groups. Comparisons of EM and IM test results with neuropsycholo gical test scores revealed several effects, including significant corr elations (a) between EM scores on both tests and performance on standa rd memory tests in both aged groups and (b) between IM scores of both aged groups on WSC and frontal-lobe test performance. The results prov ide evidence of a double dissociation with respect to involvement of b rain regions in EM and IM. They also indicate that repetition priming in WSC and WFC involve different mechanisms and that frontal-lobe dysf unction is a factor in reduced priming on the WSC test.