[Conditioning and synapse density. Morphometry of stratum lacunosum-moleculare of rat hippocampal CA1-region].

Male albino rats aged 13 weeks experienced a single training for bright -- dark discrimination in a Y-chamber. The numerical density of synapses determined in the stratum lacunosum-moleculare of the hippocampal area CA1 24 hours later turned out to be lower by 3.4 per cent with trained animals compared to passive controls. This difference failed, however, to prove significant.