Multichannel recording of field excitatory postsynaptic potentials (fEPSPs) in hippocampal slices from 2%DMSO + BV and RAPA + BV groups before and after theta burst stimulation. (A-C) Responses from a naive group rat (A) Photograph showing the hippocampal formation from a naïve group rat and Med-64 probe with 8 × 8 array. The asterisk indicates an electrode selected for electrical stimulation of the perforant path (PP) fibers. Real traces of 63 recording electrodes across the DG and the CA1 area in response to perforant path (PP) test stimulation before (black), 60 min after (green), and 120 min (red) after TBS. The PP-evoked network FP responses were localized in both the DG and CA1. (B) fEPSPs are negative-going (lower) in CA1. (C) fEPSPs are positive-going (upper) in the DG. fEPSP amplitudes in these two areas were potentiated by TBS stimulation of PP fibers (asterisk). Scale bar applies to both sweep sets. (D-F) Micrograph of a hippocampal slice and evoked responses from a 2%DMSO + BV group rat. (G-I) Hippocampal slices and typical sample recordings from a RAPA + BV-treated rat. (J and K) Summary of LTP experiments in hippocampal slices from naive, 2%DMSO + BV and RAPA + BV groups. The amplitude of both the DG (J) and CA1 (K) fEPSPs was normalized to pre-TBS baseline. The data were showed as means ± SD (n = 7). *P < 0.05, RAPA + BV group vs. 2%DMSO + BV group.