Fig. 6: HF-HI changes discrete chronic neuronal and synaptic properties including the AMPA/NMDA ratio and LTP at 1 month post impact.

a Schematic of the experimental design for this figure. b Stimulus input–output curve in the Schaffer collaterals of acute hippocampal slices showed no difference in synaptic recruitment between groups (n = 9), but c long-term potentiation (LTP) reveal decreased plasticity in HF-HI hippocampus (n = 9 per group). d Paired-pulse ratio estimated from the EPSC recording was elicited with stimuli delivered 50 ms apart (n = 9 per group). e Example traces of miniature excitatory postsynaptic currents (mEPSC) for sham and HF-HI mice. f Mean amplitude of mEPSCs per cell and cumulative fraction of amplitudes did not show any difference between groups (n = 8 mice per group). g Mean inter-event interval of mEPSCs and cumulative fraction of inter-event interval did not show differences between groups (n = 8 mice per group). h Example traces of voltage-clamp recordings at −70 or + 40 mV to identify AMPA- and NMDA-mediated EPSC. The AMPA/NMDA ratio was decreased in HF-HI CA1 neurons (n = 11 per group; *P = 0.018, unpaired, two-tailed t test). i Representative traces of voltage responses of CA1 neurons to 20 pA step depolarizing current injections. There was no difference between groups in the frequency of action potential firing in response to depolarizing current injections (n = 11 mice per group). j Example traces of voltage responses in CA1 neurons to 20 pA step hyperpolarizing current injections for sham (top) and HF-HI (bottom) mice. k Rheobase, l V₁rectification indicating inward rectifying potassium currents, and m V₂ sag of the voltage response indicating lh current, all showed no difference between sham and HF-HI CA1 neurons (n = 11 per group). Data are shown as mean ± SEM.