Hippocampal long-term potentiation does not affect either discrimination learning or reversal learning of the rabbit...

The theoretical premise that the acquisition and storage of information occurs through the strengthening of synaptic connections has contributed to the popularity of long-term potentiation (LTP) as a candidate neural mechanism for associative learning. However, whether experimentally induced LTP facilitates, disrupts, or has no effect on subsequent learning is a controversial issue. The present study examined the reported facilitative effect of LTP within hippocampal perforant path-dentate gyrus synapses on subsequent discriminative conditioning of the rabbit nictitating membrane response. In addition, the effect of LTP on subsequent reversal learning of the initial discrimination was examined. LTP did not significantly affect acquisition of the initial discriminative response or subsequent reversal learning. Furthermore, the magnitude of LTP could not be used to predict the rate of acquisition of either task. The failure to find an effect of LTP on classical conditioning of the rabbit nictitating membrane response mirrors the recent failures to replicate the disruptive effect of LTP on spatial learning in the rat. Thus, the potential contribution of an LTP-like mechanism to associative learning remains equivocal.