Synaptic plasticity in the hippocampus of awake C57BL/6 and DBA/2 mice: Interstrain differences and parallels with behavior

C57BL/6 mice consistently outperform DBA/2 mice in a range of hippocampal-d ependent spatial learning behaviors. We recorded evoked responses from the dentate gyrus of awake, freely-moving mice and measured synaptic plasticity (LTP) and performance in a hippocampal-dependent task in individual animal s from these two inbred strains. Spatial alternation tasks confirmed the be havioral divergence between the two strains, with C57BL/6 mice demonstratin g more robust alternation than DBA/2 mice. Recording changes in field poten tials in the dentate gyrus following three different high-frequency stimula tion paradigms in the same groups of animals revealed differences in neural plasticity: both strains were able to support long-term potentiation (LTP) at perforant path synapses, but brief high-frequency stimulation induced l arger and longer potentiation of the population spike in C57BL/6 than in DB A/2 mice. This greater propensity for population-spike potentiation in the strain that performed better in a hippocampal-dependent task is in accord w ith the different neurochemical profiles of C57BL/6 and DBA/2 mice. Hippoca mpus 2001;11:391-396. (C) 2001 Wiley-Liss, Inc.