Context versus content: contributions of the hippocampus and cortical organization to spatiotemporal memory

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dc.contributor.authorDemchuk, Aubrey M.
dc.contributor.supervisorMcNaughton, Bruce L.
dc.date.accessioned2023-08-15T20:40:24Z
dc.date.available2023-08-15T20:40:24Z
dc.date.issued2023
dc.degree.levelPh.D
dc.description.abstractDuring learning, the hippocampus is proposed to link the distributed components of neocortical memory representations to a spatiotemporal framework. However, the continued involvement of the hippocampus after memory consolidation is debated. Moreover, the relative encoding of spatial context (descending ‘where’ information) versus sensory content (ascending ‘what’ information), and how cortical architecture supports these interactions, remains poorly understood. Thus, in vivo two-photon microscopy of genetically encoded Thy1-GCaMP6s calcium indicator mice was used to longitudinally image cortical volumes from retrosplenial and motor cortices during behaviour both before and after bilateral lesions of the dorsal hippocampus. While the global spatial context remained constant throughout training and imaging, two familiar obstacles were added, interchanged, or removed from a cued treadmill to decouple sensorimotor activity from location-specific activity. The results support that (1) the online binding of unreliable sensory attributes to a coherent spatial framework remains mediated by the hippocampus in pre-operatively familiar environments, (2) the descending suppression of cortical responses by the hippocampus obeys hierarchical interareal and interlaminar gradients opposite to the flow of ascending sensory inputs, (3) motor cortices exhibit weak columnar spatial tuning, and (4) probabilistic cell dynamics drive the temporal drift of memory representations. Altogether, even in familiar environments, the hippocampus appears to actively integrate current sensory information with an internal model of the environment and propagate top-down predictions throughout the cortical hierarchy to improve the efficiency of ongoing information processing.
dc.identifier.urihttps://hdl.handle.net/10133/6566
dc.language.isoen
dc.proquest.subject0317
dc.proquestyesYes
dc.publisherLethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience
dc.publisher.departmentDepartment of Neuroscience
dc.publisher.facultyArts and Science
dc.relation.ispartofseriesThesis (University of Lethbridge. Faculty of Arts and Science)
dc.subjectHippocampus
dc.subjectSpatiotemporal memory
dc.subjectCortical
dc.subjectSpatial context
dc.subjectSensory content
dc.subject.lcshHippocampus (Brain)
dc.subject.lcshDissertations, Academic
dc.titleContext versus content: contributions of the hippocampus and cortical organization to spatiotemporal memory
dc.typeThesis
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