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Differential connectivity of perirhinal and parahippocampal cortices within human hippocampal subregions revealed by high-resolution functional imaging.

Abstract

Numerous studies support the importance of the perirhinal cortex (PRC) and parahippocampal cortex (PHC) in episodic memory. Theories of PRC and PHC function in humans have been informed by neuroanatomical studies of these regions obtained in animal tract-tracing studies, but knowledge of the connectivity of PHC and PRC in humans is limited. To address this issue, we used resting-state functional magnetic resonance imaging to compare the intrinsic functional connectivity profiles associated with the PRC and PHC both across the neocortex and within the subfields of the hippocampus. In Experiment 1, we acquired standard-resolution whole-brain resting-state fMRI data in 15 participants, and in Experiment 2, we acquired high-resolution resting-state fMRI data targeting the hippocampus in an independent sample of 15 participants. Experiment 1 revealed that PRC showed preferential connectivity with the anterior hippocampus, whereas PHC showed preferential connectivity with posterior hippocampus. Experiment 2 indicated that this anterior-posterior functional connectivity dissociation was more evident for subfields CA1 and subiculum than for a combined CA2/CA3/dentate gyrus region. Finally, whole-brain analyses from Experiment 1 revealed preferential PRC connectivity with an anterior temporal and frontal cortical network, and preferential PHC connectivity with a posterior medial temporal, parietal, and occipital network. These results suggest a framework for refining models of the functional organization of the human medial temporal lobes in which the PRC and PHC are associated with distinct neocortical pathways that, in turn, may differentially interact with regions along the anterior-posterior axis of the hippocampus.

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  • Authors

    Libby LA, Ekstrom AD, Ragland JD, Ranganath C

    Institution

    Department of Psychology, University of California, Davis, Davis, CA 95616, USA. lalibby@ucdavis.edu

    Source

    The Journal of neuroscience : the official journal of the Society for Neuroscience 32:19 2012 May 9 pg 6550-60

    MeSH

    Cerebral Cortex
    Female
    Follow-Up Studies
    Hippocampus
    Humans
    Magnetic Resonance Imaging
    Male
    Neural Pathways
    Parahippocampal Gyrus
    Young Adult

    Pub Type(s)

    Comparative Study
    Journal Article
    Research Support, N.I.H., Extramural
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22573677