Spatial memory deficit following fimbria-fornix lesions: independent of time for stimulus processing.

The present experiment examined the possible role of stimulus processing time in the spatial memory deficit found following fimbria-fornix lesions in rats. Rats were trained preoperatively on a radial arm maze in a procedure that placed them at the end of each arm and confined them there for 30 seconds. This confinement period was markedly longer than the few seconds the rats normally spend there in the usual test procedure. Rats with fimbria-fornix lesions performed no better than expected by chance on the first choice after placements. Although performance on subsequent choices was above chance, this was due to a strong turning pattern; when this pattern was interrupted, performance was no greater than that expected by chance on all choices. These data demonstrate that the deficit in the radial arm maze resulted primarily from a difficulty in spatial memory, rather than from an insufficient time for processing stimulus information.