Fig. 13

Examples of fEPSPs and PS evoked by three representative stimulation frequencies in a dorsal and a ventral hippocampal slice obtained before (Control) and during application of the agonist of μ-opioid receptors (μ-ORs) fentanyl (Fentanyl). Experiments were performed at stimulation current intensity that produced PS with amplitude of 0.5–1 mV. Single traces on the left of first PS and fEPSP traces (i.e. in the 5 Hz example) in each panel represent the first response of the 0.1 Hz train with which each frequency stimulation experimental procedure started; time calibration bars, 5 ms. Amplitude calibration bar for all records, 1 mV. Stimulation artifacts are truncated for clarity