IMPLICIT AND EXPLICIT MEMORY RETRIEVAL WITHIN AND ACROSS THE DISCONNECTED CEREBRAL HEMISPHERES

The authors report that the divided right and left cerebral hemisphere s are both adept at priming, a type of implicit memory, and that subco rtical routes can mediate implicit memory retrieval across the hemisph eres. Two individuals with complete section of all forebrain commissur es, L.B. and N.G., were given tests of recall and recognition (explici t memory) and stem-completion priming (implicit memory). The right and left hemispheres of N.G. and the left hemisphere of L.B. exhibited si gnificant intrahemispheric priming. Interhemispheric priming was simil ar in extent to intrahemispheric priming. Under several intra- and int erhemispheric conditions, significant implicit retrieval occurred in t he face of abnormal explicit retrieval, Because all forebrain commissu res had been severed in L.B. and N.G., interhemispheric priming was ne cessarily supported by subcortical structures. The observed dissociati on between explicit and implicit memory performance indicates that the routes of interhemispheric transfer vary with type of memory retrieva l.