The efficacy of response prevention on avoidance behavior in young and adult rats with prefrontal cortical injury.

Five days prior to one-way active avoidance training, 36 rats of 18-20 days of age and 36 rats of 110-130 days received dorsomedial, ventrolateral or sham lesions. During acquisition, the CS consisting of the raising of a guillotine door was followed 5 sec later by footshock US onset unless a response was emitted. After acquisition, subjects of each surgical condition were given 1 of 3 extinction treatments. Twelve pups and 12 adults received 5 response prevention trials, in which a second door blocked responses upon CS onset. The same number of subjects was given a delay prior to extinction, and the remaining subjects began extinction immediately following acquisition. Both lesion conditions interfered with adult acquisition, but produced superior acquisition in the lesioned pups, as measured by trials to criterion and trial speeds. In extinction, response prevention seriously disrupted the sham adults, as did the delay condition to a lesser extent. Resistance to extinction decreased to an equivalent extent after both response prevention and delay in the sham pups. An overall disruption in extinction was found in the adult lesioned groups, although there was some evidence of response prevention and delay equivalency in the medial adults. The lesioned pups showed a dramatic persistence responding. A test of passive avoidance to the previous shock compartment was administered 24 h later. Both response prevention and delay treatments in the adults produced residual fear, which was not found in the pups. Rather, all pups behaved with characteristic response inhibitory deficits. The results were considered in light of the prefrontal mediation of response inhibitory centers during ontogeny.