One-trial visual recognition in cats: the role of the rhinal cortex.

Memory for visual recognition in primates is at least partially mediated by the peripheral and entorhinal (i.e., rhinal) areas of the cerebral cortex. The roles of these structures in visual recognition in cats was studied by producing electrolytic combined lesions of the rhinal (perirhinal + entorhinal) areas in a group of cats trained in a modified Wisconsin test apparatus to delayed selection of an object on the basis of its image on presentation of a new object in every trial in the test. Control groups consisted of intact and sham-operated cats. Animals with rhinal lesions were no different from sham-operated and intact animals in the initial training to the rules for correct responding to the objects presented; they also showed no difference at the minimum delay period of 5 sec used in these experiments. However, a statistically significant difference was seen on testing with a delay of 10 sec, demonstrating impairment of intrinsic visual recognition memory.