Severe deficits of adaptive behaviour after lesions of rat's nucleus reticularis pontis oralis.

Hooded rats of the Long-Evans strain with bilateral symmetric lesions of the nucleus reticularis pontis oralis (RPO) displayed locomotor hyperactivity in the open field (OF) compared with their preoperative values. Their locomotor velocity and their climbing rate were significantly enhanced. Habituation in the OF was significantly weakened. The lesioned rats were unable to acquire any active avoidance responses in a Y-maze or a jump test. They were unable to correctly perform preoperatively learned avoidance responses and could not relearn the tasks. Reaction times to the conditioned stimulus increased and more often the rats escaped only after the onset of the punishment; even their escape responses were instable. The lesioned rats were neurologically inconspicuous. One can assume that the RPO participates in a functional system for control and recall of learned (not inborn) programs.