Prefrontal control of trace eyeblink conditioning in rabbits: role in retrieval of the CR?

Rabbits (Oryctolagus cuniculus) were trained on a trace eyeblink (EB) conditioning task to a criterion of 10 consecutive EB conditioned responses (CRs). One week later, ibotenic acid or sham lesions were made in the mPFC centered on the prelimbic region (Brodmann's area 32) or the cingulate cortex (Brodmann's area 24). Following a 1-week postoperative recovery period, all animals were retrained for 4 consecutive days using the same parameters as during acquisition, given 1 week off, and retrained for another 4 days. Mean EB conditioning deficits in the group with area 32 lesions occurred on the first and second days of each retraining period. However, by the third and fourth days of retraining, these lesioned animals were performing at a level comparable to that of the sham group. Lesions of area 24 did not produce deficits at either retesting period. These findings were interpreted to indicate that area 32, but not area 24, is involved in retrieval processes, rather than consolidation or storage, in that the animals were impaired at both retesting times, but were able to relearn the task.