Figure 6.
Effect of bilateral microinfusion of WIN into the mPFCv and latPFC on DR 5-HT neuronal activity. A, Integrated firing rate histogram of a 5-HT neuron showing a robust but slow-onset increase in single-unit activity after intra-mPFCv infusion of WIN (5 μg in 0.5 μl of vehicle) in four of five neurons. This effect was abrogated by RIM (1.0 mg/kg, i.v.). B, Integrated firing rate histogram of a 5-HT neuron before and after intra-mPFCv infusion of WIN (5 μg in 0.5 μl of vehicle) showing an abolition of increased single-unit activity resulting from total prefrontocortical transection (n = 2 neurons). The microinfusion site was anterior to the transection lesion. C, Integrated firing rate histogram of a 5-HT neuron before and after intra-mPFCv infusion of vehicle (0.5 μl), showing no apparent effect on neuronal activity (n = 4 neurons). D, Integrated firing rate histogram showing that intra-latPFC infusion of WIN (5 μg in 0.5 μl of vehicle) did not produce an increase in 5-HT single-unit activity (n = 2 neurons). On each histogram, 5-HT neuronal firing rate is plotted as spikes per 10 s. Horizontal bar represents the time course of infusion, and vertical lines at the bottom represent the frequency of neuronal burst discharge such that each tick corresponds to a burst event. E, Illustrative depiction of the placement of cannulas directed into the mPFCv (shaded region area, bregma +2.2) and the electrode descent into the dorsal raphe nucleus (interaural 0 + 1.2), based on the stereotaxic atlas of Paxinos and Watson (1986).
