Electrical activity of the dorsal hippocampus in rats operantly trained to lever press and to lick.

Abstract

One group of four rats was operantly conditioned in a Sidman avoidance procedure to lever press during one discriminative stimulus and to lick during another discriminative stimulus. Another group of four rats was conditioned in a similar manner in order to receive positive reinforcements. More dorsal hippocampal rhythmic slow activity (RSA) occurred during lever pressing than during operant licking. It was also found that dorsal hippocampal RSA accompanied walking and that dorsal hippocampal large irregular activity occurred during periods of immobility, during normal drinking and grooming and during the intense saliva spreading and grooming that were induced by exposure to a 40 degrees C environmental temperature. The data suggested that hippocampal RSA is related to type of response rather than to sensory, motivational, or learning processes. Furthermore, the data suggested that RSA is not related to the operant role of response or to relative vigor of response.