Rats with chronically implanted electrodes in the dorsal hippocampus and fornix were operantly conditioned in a straight alley to press a bar placed at one end of the alley and to run for the water reward available at the other end. Both start and run times increased during hippocampal stimulation, but were differentially affected after electrolytic lesion of the fimbria-fornix system. The effect of stimulation on start times was abolished after the lesion, while the effect of stimulation on running remained unaltered. Perseverance of bar pressing was significantly higher during stimulation of the hippocampus, and this effect was abolished after fornix lesion. Threshold for stimulation effects increased with distance away from the pyramidal layer. These findings question the validity of a simple inhibitory explanation.
ASJC Scopus subject areas
- Environmental Science(all)
- Earth and Planetary Sciences(all)