Epileptiform activity induces a use-dependent synaptic potentiation at B2

<p>–<b>B2 synapses.</b> (A) Sample electrophysiological recordings of five consecutive EPSPs evoked at the basal rate of 0.05 Hz. Synapses were tested before and every 15 minutes after PTZ treatment and washout. An enhancement of synaptic strength was detectable at both 15 and 30 minutes after drug washout. (B) Bar graph of the mean amplitude of the first EPSP in treated synapses. EPSP amplitudes recorded before and at the end of PTZ exposure were similar. Conversely, a significant potentiation of 218.30±46.77% and 265.50±59.31% of pre-treatment value occurred at 15 and 30 minutes post-treatment, respectively. (C) Unchanged values were measured in the control group at any time-point. (D,E) Time course of EPSP amplitude in treated and untreated monosynaptic connections stimulated at 0.05 Hz. Values were expressed as percentages of the first EPSP amplitude to better appreciate the trend of EPSPs recorded at 15 and 30 minutes after PTZ washout. (F) Bar graph of EPSP rise times measured at each experimental time-point, showing that epileptiform activity temporarily speeded up the kinetics of release. (G) No significant difference was found in control group.