Figure 6.

D2 receptor-dependent modulation of current-evoked action potential firing in interneurons from saline- and cocaine-treated animals. (a) Examples of fast-spiking (FS) and non-fast spiking (NFS) interneurons recorded in the prelimbic cortex of adult rats. Cells were filled with Alexa 594 during whole-cell recording and reconstructed using z-stacked confocal images. Scale bar is 50 μm. (b) Example sweeps showing that D2 receptor stimulation with quinpirole (5 μM) increases the action-potential firing evoked by somatic current injection in both NFS and FS cells from saline-treated animals (left column), but not from cocaine-treated animals. Scale bars represent 200 ms and 20 mV. (c) Summary plot for the effects of quinpirole on evoked spike firing in FS cells (open symbols) and NFS cells (gray squares) in saline- and cocaine-treated animals. Individual values for each cell are averages of at least three repetitions for baseline and quinpirole condition. (d) Same data as in (c) plotted to show the average change in the number of action potentials for FS and NFS cells in saline- and cocaine-treated animals (^*p<0.05 paired t-tests).