The relationship between LTP and spatial learning in the rat was investigated here in a two-part study. Part 1 tested the hypothesis that artificially driving hippocampal synapses to their maximum strength would preclude any further naturally-occurring changes and so disrupt the subsequent spatial learning function of the hippocampus. Part 2 investigated the above LTP-learning correlation in more detail. First, the order of training and LTP induction was reversed to see whether induction of LTP may have caused the corresponding distribution of spatial learning previously. Although poor-learning rats again showed less LTP the correlation was much lower than in the previous experiments, both for the group trained first and the group trained afterwards. Possible reasons were explored in the final experiment. The three main results of this thesis therefore are that (1) contrary to previously reported findings, induction of LTP in the perforant path does not appear to impair spatial learning, (2) the amount of LTP after repeated induction declines with increasing test stimulus intensity at a rate proportional to its initial magnitude and (3) there is a clear relationship between underlying synaptic plasticity and learning ability. It appears that this relationship is in the opposite direction to that predicted by computational theories of learning: namely, animals showing poor learning ability may demonstrate increased rather than decreased plasticity. These results provide clear support for a link between hippocampal synaptic plasticity and spatial learning but raise questions as to the nature of the relationship.