SPATIAL VIEW CELLS IN THE PRIMATE HIPPOCAMPUS - EFFECTS OF REMOVAL OFVIEW DETAILS

Hippocampal function was analyzed by making recordings from hippocampa l formation neurons in macaques actively walking in the laboratory. '' Spatial view'' cells, which respond when the monkey looks at a part of the environment were analyzed. It is shown that many of these cells r etain their spatial characteristics when the view details are obscured totally by curtains and by darkness. It is shown that many of these c ells respond more when the monkey is gazing toward one location in the room than toward other locations, even though none of the view detail s can be seen. Such cells were found in the CA1 region, the parahippoc ampal gyrus, and the presubiculum. Other cells stopped responding when the monkey looked toward the normally effective location in the envir onment if the view details were obscured. These cells were in the CA3 region of the hippocampus. The results indicate that for CA3 cells, th e visual input is necessary for the normal spatial response of the neu rons, and for other cells in the primate hippocampal formation, the re sponse still depends on the monkey gazing toward that location in spac e when the view details are obscured. These latter cells therefore cou ld reflect the operation of a memory system, in which the neuronal act ivity can be triggered by factors that probably include not only eye p osition command/feedback signals, but also probably vestibular and/or proprioceptive inputs. This representation of space ''out there'' woul d be an appropriate part of a primate memory system involved in memori es of where in an environment an object was seen and more generally in the memory of particular events or episodes for which a spatial compo nent normally provides part of the context.