Krasnow Institute > Monday Seminars > Abstracts

Hippocampal Place Fields
and
Spatial Landmarks:
Translations, Rotations, and Relations

James Knierim
Krieger Mind/Brain Institute, Johns Hopkins University

Place cells of the rat hippocampus combine information from self-motion and from external sensory cues to define their spatially selective firing fields.    The interactions among these cues can be complex.  Data from the brain regions that are afferent to the hippocampus suggest that an internally generated, spatial framework is encoded by the medial entorhinal grid cell system, using primarily self-motion cues.  This framework exists independent of external sensory cues, but it requires input from external cues to align with the external world.  Distal cues primarily set the orientation of the internal framework relative to the external world, most likely via the head direction cell system.  Local cues and geometric boundaries  primarily set the phase, or translational shift, of the framework.  Behavioral data are consistent with neurophysiological data that demonstrate that animals represent environments based more strongly on a spatial coordinate frame bound to the local apparatus rather than the distal room cues. 

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