Computer simulation of hippocampal place cells

Hippocampal pyramidal cells show location-specific firing as animais navigate through an environment. It has been suggested that this firing could resuit from the “local view” available in a cell’s field. Hippocampal damage results in learning deficits on a wide variety of tasks. This, along with the fact that an associative form of plasticity has been discovered in the hippocampus has led to the idea that this structure might serve as a distributed, associative-matrix memory device. Here, these ideas are combined in a model in which pyramidal cells are the output layer of a competitive-learning, pattern-classification device. The inputs are patterns of environmental stimuli as viewed by a computerized “rat” from various locations within a simulated environment. These patterns are “classified” on the basis of their similarity. Since views available from contiguous regions of space are similar, single cells come to fire in a circumscribed region (place field). Firing-rate maps for these theoretical units show place fields remarkably similar to those of actual place cells. Also, they show remarkably similar behavior to that of real cells when tested under some of the probe conditions similar to those which have been used for actual cells.