Fig. 2: HF-HI reduces synaptic plasticity through modifications to synaptic function. | Nature Communications

Fig. 2: HF-HI reduces synaptic plasticity through modifications to synaptic function.

From: High-frequency head impact causes chronic synaptic adaptation and long-term cognitive impairment in mice

Fig. 2: HF-HI reduces synaptic plasticity through modifications to synaptic function.The alternative text for this image may have been generated using AI.

a Schematic of the experimental design. b Dendritic spine analysis of CA1 neurons shows that there was no effect of HF-HI on spine density (n = 48 sham and 49 HF-HI neurons from 5 mice/group, insert box = 20 µm). c Stimulus input–output curve in the Schaffer collaterals of acute hippocampal slices (n = 8) and d long-term potentiation (LTP) reveal decreased plasticity in HF-HI hippocampus (n = 8 per group). e Paired-pulse ratio (n = 8 sham, n = 10 HF-HI). f Example traces of miniature excitatory postsynaptic currents (mEPSC) for sham (top) and HF-HI (bottom) mice. g Mean amplitude of mEPSCs per cell and a cumulative fraction of amplitudes were unchanged between groups (n = 8 mice per group). h Mean inter-event interval of mEPSCs and cumulative fraction of inter-event interval per group showed that mEPSC frequency was decreased in HF-HI CA1 neurons (n = 8 per group. *P = 0.011, unpaired, two-tailed t test). i 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 = 0.031, unpaired, two-tailed t test). j Representative traces of voltage responses of CA1 neurons to 20 pA step, depolarizing current injections. Frequency of action potential firing in response to depolarizing current injections was decreased in HF-HI CA1 neurons (n = 8 per group; **P = 0.0019; ***P = 0.001, ****P < 0.0001, two-way repeated-measures ANOVA with Bonferroni post hoc). k Example traces of voltage responses in CA1 neurons to 20 pA step, hyperpolarizing current injections for sham (top) and HF-HI (bottom) mice. l Approximate rheobase was increased in HF-HI CA1 neurons (n = 8 per group; unpaired, two-tailed t test, **P = 0.0019). m V1 rectification indicating the inward rectifying potassium currents was increased in HF-HI CA1 neurons (n = 8; unpaired, two-tailed t test, *P = 0.049), but n sag of the voltage response indicating Ih current (V2 sag) was unchanged (n = 8). Data are shown as mean ± SEM.

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