Sex differences in hippocampal long-term potentiation (LTP) and Pavlovian fear conditioning in rats: positive correlation between LTP and contextual learning - PubMed (original) (raw)

Comparative Study

. 1994 Oct 24;661(1-2):25-34.

doi: 10.1016/0006-8993(94)91176-2.

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Comparative Study

Sex differences in hippocampal long-term potentiation (LTP) and Pavlovian fear conditioning in rats: positive correlation between LTP and contextual learning

S Maren et al. Brain Res. 1994.

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Abstract

Three experiments investigated sex differences in hippocampal long-term potentiation (LTP) and Pavlovian fear conditioning in rats. Experiment 1 revealed a robust sex difference in the magnitude of LTP induced at perforant path synapses in the dentate gyrus of pentobarbital-anesthetized rats. This sex difference in LTP was evident in rats of 35 and 60 days of age and was not the result of pre-LTP sex differences in perforant path synaptic transmission; 20-day-old rats did not show LTP. An analysis of field potentials evoked during LTP induction revealed a sex difference in the magnitude of N-methyl-D-aspartate (NMDA) receptor activation that was highly correlated with the magnitude of LTP. Experiment 2 showed that males condition more fear, measured as freezing, to the contextual conditional stimuli (CSs) of a conditioning chamber compared to their female counterparts. This sex difference in conditional freezing was apparent with both low and high unconditional stimulus (US, footshock) intensities. Experiment 3 revealed that the enhanced fear conditioning in males was specific to contextual CSs, and consisted of a more rapid rate of conditioning. Together, these experiments reveal a positive correlation between the magnitude of hippocampal LTP and a form of learning that depends on the hippocampus. Furthermore, they suggest a neural basis for sex differences in hippocampus-dependent learning tasks.

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