The hippocampus as a cognitive map: From grid cells to navigation
The classic book of O’Keefe and Nadel (1978) has inspired a vibrant research program about animal and human navigation to the present day. But is the hippocampus technically a “map” and in what sense is it “cognitive”? Many results about place cells in the hippocampus have recently been clarified by the breakthrough discovery of g rid cells and their remarkable hexagonal activity patterns in the entorhinal cortex (Hafting et al., 2005). This talk will summarize recent modeling results concerning how both grid and place cell maps may be learned in a hierarchy of self-organizing maps as an animal navigates through space. The model clarifies why both types of cells are needed, how top-down cognitive mechanisms may modulate this map, how various observed oscillations may emerge from these learning mechanisms, and how What and Where spatial representations and adaptively-timed object representations may both arise from variations of a shared hippocampal circuit design. In particular, top-down matching and attentional mechanisms may help to stabilize and reset cell properties in this mapping hierarchy and regulate the occurrence of beta and gamma oscillations. The talk will also discuss how optic-flow based navigation and tracking may be achieved in response to natural environments through interactions of visual cortical regions, and how spatial and object attention may interact to learn to recognize and search objects and scenes as part of the information acquisition process during navigation, including roles for perirhinal and parahippocampal cortex in learning object and spatial contextual information.
Supported in part by CELEST, an NSF Science of Learning Center (SBE-0354378), and the SyNAPSE program of DARPA (HR0011-09-C-0001).
References (see http://cns.bu.edu/~steve)
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