Separate Neural Bases of Two Fundamental Memory Processes in the Human Medial Temporal Lobe

TLDR

Functional MRI was used to record BOLD signals in medial temporal lobe structures during encoding of complex scenes or line drawings and during retrieval of line drawings or words. Encoding activated posterior medial temporal cortex, especially the parahippocampal cortex, while retrieval activated anterior medial temporal cortex, particularly the subiculum, demonstrating distinct medial temporal lobe components for encoding and retrieval.

Abstract

The participation of medial temporal-lobe structures in memory performance was examined by functional magnetic resonance imaging of local blood oxygenation level–dependent signals. Signals were measured during encoding into memory complex scenes or line drawings and during retrieval from memory of previously studied line drawings or words. Encoding tasks yielded increased signals for unfamiliar information in a posterior medial-temporal region that were focused in the parahippocampal cortex. Retrieval tasks yielded increased signals for successfully remembered information in an anterior medial-temporal region that were focused in the subiculum. These results indicate that separate components of the human medial temporal-lobe memory system are active during distinct memory processes.