SEPARATE NEURAL BASES OF 2 FUNDAMENTAL MEMORY PROCESSES IN THE HUMAN MEDIAL TEMPORAL-LOBE

The participation of medial temporal-lobe structures in memory perform ance was examined by functional magnetic resonance imaging of local bl ood oxygenation level-dependent signals. Signals were measured during encoding into memory complex scenes or line drawings and during retrie val from memory of previously studied line drawings or words. Encoding tasks yielded increased signals for unfamiliar information in a poste rior medial-temporal region that were focused in the parahippocampal c ortex. Retrieval tasks yielded increased signals for successfully reme mbered information in an anterior medial-temporal region that were foc used in the subiculum. These results indicate that separate components of the human medial temporal-lobe memory system are active during dis tinct memory processes.