A COMPARISON OF THE EFFECTS OF 2 FIMBRIA-FORNIX LESION TECHNIQUES ON BEAM-WALKING PERFORMANCE IN THE RAT - ASPIRATION VERSUS ELECTROLYSIS

This experiment was aimed at comparing the sensorimotor correlates of fimbria-fornix lesions made with either a classical aspiration techniq ue that also removes part of the overlying cortical structures, or an electrolytic one that does not encroach upon these cortical structures . About 4 months after lesion surgery, Long-Evans female rats which ha d sustained an aspiration or an electrolytic fimbria-fornix lesion at the age of 90 days were tested to measure their beam-walking performan ce as an index for their sensorimotor capabilities. We found that afte r an aspiration lesion, the rats presented sensorimotor deficits which did not occur after an electrolytic lesion. After having found that e lectrolytic lesions of the fimbria and the fornix produced neurochemic al deficits (in the dorsal hippocampus) and cognitive alterations clos e to those resulting from aspiration lesions, it is concluded from the present experiment that the electrolytic lesion technique is an inter esting alternative to an aspiration technique, essentially because the former does not induce the sensorimotor deficits due to the partial d amage that an aspiration technique produces in the medial parietal cor tex. As the electrolytic lesion technique may minimize the risk of int roducing a sensorimotor bias in the accuracy of cognitive evaluations, the present result might be of interest to neuroscientist using a fim bria-fornix lesion paradigm in order to investigate the efficacy of dr ugs, grafts or other treatments on the recovery from cognitive deficit s.