Abstract
The effects of small electrolytic lesions in the medial septal region on retention of a spatiotemporal task (contingently reinforced T-maze alternation) were determined in Long-Evans rats. With brief intertrial intervals (massed trials), control rats were only slightly (if at all) affected by the 17-day vacation from testing during the period of postoperative recovery.The experimental rats with medial septal lesions, on the other hand, dropped to chance levels of alternation and then recovered to a statistically significant but slight amount over nine sessions of postoperative testing. With long intertrial intervals produced by running the animals in squads of four, control rats dropped to chance levels of alternation and then recovered somewhat over seven additional sessions of testing. Animals with septal lesions tended to perseverate and showed no evidence of recovery. Results were interpreted to indicate that a major hippocampal afferent system (dorsal fornix) plays a crucial role in mediating the spatiotemporal construction and use by the brain of the “cognitive maps” necessary for successful T-maze alternation.
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The authors are indebted to Jean A. Conlon for assistance with the histological materials and to Louise Behrens for assistance in preparing the manuscript. The study was partially supported by a fellowship (No. PRA-59768) from the Organization of American States to G.N.O.B.
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Thomas, G.J., Brito, G.N.O. & Stein, D.P. Medial septal nucleus and delayed alternation in rats. Psychobiology 8, 467–472 (1980). https://doi.org/10.3758/BF03326477
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DOI: https://doi.org/10.3758/BF03326477