Fig. 16

Steady-state (a) and onset responses (b) for synaptic input (fEPSP) and neuronal output (PS) in DH and VH under control conditions (open circles) and during activation of μ-Ors by fentanyl (filled circles) plotted against stimulation frequency. Data shown were obtained with suprathreshold stimulation. Horizontal bars above curves indicate the frequency range were statistically significant differences were observed between control and drug condition (paired t-test at p < 0.05). Note that symbols in a, for VH–fEPSP, showing results in the two conditions are overlapped between each other