Averaged evoked potentials were recorded from the outer molecular layer of the denate gyrus in freely moving rats undergoing tests of stimulus generalization during performance of an auditory discrimination task. Results indicated that the two major negative components (N1 and N2) were reciprocally related to the degree of stimulus generalization as indicated by the behavioral response gradient. The N1 component was larger when stimuli were least similar in frequency to the originally trained stimulus, whereas the N2 component was smaller under those same conditions. Destruction of either the entorhinal cortex or the medial and lateral septal nuclei resulted in differential alterations in both stimulus generalization behavior and components of the averaged potentials from the outer molecular layer. The results suggest differential functional roles for the septal and entorhinal projections to the dentate gyrus of the rodent hippocampal formation.
ASJC Scopus subject areas
- Developmental Neuroscience