Tonic and Phasic Firing of Rat Hippocampal Complex-Spike Cells in Three Different Situations: Context and Place

The firing of hippocampal complex-spike cells has previously been demonstrated to be related to a rat’s position in its environment. In this paper we examine the firing of individual complex-spike cells in three familiar environments: an Olton radial maze, an operant chamber with a DRL-16 schedule in effect, and a home box with the rat’s pups. We have found that individual neurons have spatial fields in several environments, and that the position of the fields is stable within an environment but unpredictable from one environment to the next. We have also found that tonic firing rates are stable in one environment but vary dramatically and unpredictably from one situation to another. The results are interpreted in terms of a hippocampal context system.