A dissociation of encoding and retrieval processes in the human hippocampus.
The hippocampal formation performs two related but distinct memory functions: encoding of novel information and retrieval of episodes. Little evidence, however, resolves how these two processes are implemented within the same anatomical structure. Here we use high-resolution functional magnetic resonance imaging to show that distinct subregions of the hippocampus are differentially involved in encoding and retrieval. We found that regions early in the hippocampal circuit (dentate gyrus and CA fields 2 and 3) were selectively active during episodic memory formation, whereas a region later in the circuit (the subiculum) was active during the recollection of the learning episode. Different components of the hippocampal circuit likely contribute to different degrees to the two basic memory functions.
Eldridge
Laura L
LL
Department of Psychology, University of California, Los Angeles, Los Angeles, California 90095, USA.
Engel
Stephen A
SA
Zeineh
Michael M
MM
Bookheimer
Susan Y
SY
Knowlton
Barbara J
BJ
D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D005071:Evoked Potentials / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000098:blood supply / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D011939:Mental Recall / Q000502:physiology*; D009415:Nerve Net / Q000098:blood supply / Q000502:physiology*; D009434:Neural Pathways / Q000098:blood supply / Q000502:physiology*; D021641:Recognition, Psychology / Q000502:physiology*; D013997:Time Factors