Fig. 7.
Representative data from individual neurons recorded from experiments using 20 Hz train stimulation of the FF. Each panel represents 10 overlaid traces, and gray arrows denote time points where the FF was stimulated. A, Example of a neuron in the control condition (stimulation intensities: FF = 1000 μA, VTA = 750 μA). Train stimulation of the FF by itself reliably evoked firing over all five pulses of the train (A1). Burst stimulation of the VTA 10 msec before train stimulation of the FF drastically reduced firing evoked by the first pulse in the train, whereas firing evoked by the latter pulses was relatively unaffected (A2). For clarity, only the last pulse of the VTA burst (VTA stim) is shown. B, Example of a neuron pretreated with the D1 receptor antagonist SCH23390 (stimulation intensities: FF = 680 μA, VTA = 600 μA). As was observed in control neurons, train stimulation of the FF by itself reliably evoked firing over all five pulses of the train (B1). However, in the presence of SCH23390, burst stimulation of the VTA completely abolished firing evoked by pulses 1–2 and substantially reduced firing evoked by latter pulses of the train (B2).