Post-TBI output (EPSP) levels as a function of input (FV slope). (A) Input/output curves were generated via stimulation of the Schaffer collaterals and medial and lateral perforant path in the dentate region. The injured group trended towards higher mean EPSP levels in CA1 and medial perforant path, and lower levels in lateral perforant path, but these were not significant at individual current levels. (B) The empirical mean EPSP is plotted as a function of mean FV slope for each level of current. In the CA1 region we found strong evidence of an interaction between injury and FV slope [F(2, 428) = 6.95, p = 0.001], indicating the presence of an injury effect that differed as a function of FV slope. These results suggest that for a given input (FV) in area CA1, there is a greater output (EPSP) post injury. The results for this interaction for medial perforant path (mPP) did not achieve statistical significance [F(2, 437) = 2.28, p = 0.10] and there was no evidence of an effect of injury by FV slope interaction in the lateral perforant path (lPP) [F(2,447) = 0.35, p = 0.70, NS]. There was also no evidence of an overall effect of injury in the lPP [F(1,6) = 0.023, p = 0.89 NS]. Data presented as animal mean ± standard error of the mean.