Neural Activity in the Dentate Gyrus of the Rat During the Acquisition and Performance of Simple and Complex Sensory Discrimination Learning

Abstract

Neural activity recorded in the outer molecular layer of the dentate gyrus changes during the course of simple and differential auditory discrimination learning. Such neural activity in the form of time-locked evoked potentials to the conditioned auditory stimulus has been correlated with 1) the acquisition, extinction and reconditioning of a simple discrimination task, and 2) maintained performance of a complex differential discrimination task. Several tests examining the possible influences of behavioral variables have indicated that the above neural activity is not generated by gross changes in the behavior of the animal during the different phases of conditioning. The sensory evoked neural activity in the dentate gyrus has been shown to reflect the inputs of two major hippocampal afferents, the septo-hippocampal fibers, and the perforant path. Recent experiments suggest that such activity may represent not only processes which are directly related to the conditioned status of the auditory stimulus in terms of its behavioral significance, but also the pattern of events which has just preceded that stimulus.