title: Contributions of human hippocampal subfields to spatial and temporal pattern separation.
abstract: We sought to explore the roles of the hippocampal subregions and adjacent medial temporal lobe regions in pattern separation and any differential contributions based on sequential or spatial information. Young adults performed an incidental-encoding task on a sequence of four objects presented on the screen in one of eight locations while we collected high-resolution functional MRI brain scans. We employed five trials of interest: first presentations, exact repetitions, lures in which the same objects were repeated in different locations (spatial lures), lures in which the same objects were presented in a different sequential order (sequential lures), and lures in which both the spatial location and sequence were changed (both lures). We found no evidence for spatial or sequential specialization in the hippocampal subfields, consistent with the hypothesis that the dentate gyrus acts as a universal pattern separator. Likewise, we did not observe specialization for the perirhinal or parahippocampal cortices for spatial or sequential information, though both regions show evidence for associative processing in this task.
authors.affiliation: Center for the Neurobiology of Learning and Memory, University of California, Irvine, California.
authors.forename: Marwa
authors.initials: M
authors.lastname: Azab
authors.forename: Shauna M
authors.initials: SM
authors.lastname: Stark
authors.forename: Craig E L
authors.initials: CE
authors.lastname: Stark
mesh_terms: D000293:Adolescent; D000328:Adult; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D018891:Dentate Gyrus / Q000502:physiology; D005260:Female; D059907:Functional Neuroimaging; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D061212:Memory, Episodic; D020534:Parahippocampal Gyrus / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: CA1; CA3; hippocampus; medial temporal lobe; sequence learning