Dynamics of the hippocampus during encoding and retrieval of face-name pairs.
The medial temporal lobe (MTL) is critical in forming new memories, but how subregions within the MTL carry out encoding and retrieval processes in humans is unknown. Using new high-resolution functional magnetic resonance imaging (fMRI) acquisition and analysis methods, we identified mnemonic properties of different subregions within the hippocampal circuitry as human subjects learned to associate names with faces. The cornu ammonis (CA) fields 2 and 3 and the dentate gyrus were active relative to baseline only during encoding, and this activity decreased as associations were learned. Activity in the subiculum showed the same temporal decline, but primarily during retrieval. Our results demonstrate that subdivisions within the hippocampus make distinct contributions to new memory formation.
Zeineh
Michael M
MM
Ahmanson-Lovelace Brain Mapping Center, UCLA School of Medicine, 660 Charles Young Drive South, Los Angeles, CA 90095-7085, USA.
Engel
Stephen A
SA
Thompson
Paul M
PM
Bookheimer
Susan Y
SY
D001931:Brain Mapping; D018891:Dentate Gyrus / Q000502:physiology*; D005145:Face; D007839:Functional Laterality; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007858:Learning; D008279:Magnetic Resonance Imaging; D008568:Memory / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology*; D009275:Names; D021641:Recognition, Psychology