dopamine was observed approximately 8 s before the lever press followed by a more pronounced and significant increase in [DA] (maximum increase of 48.0 ± 1.5 nM) immediately following response completion. Other NAc neurons (n = 6) exhibited significant increases in cell firing (peak increase is 2.51 ± 0.17 Hz) immediately following response completion (termed reinforcement-excitation or RFe cells; Figure 4B). At those sites, an overall significant increase in dopamine was observed (F5, 95 = 2.4, p < 0.001). Dopamine levels began to increase approximately 4 s prior to the response, declined slightly at response completion, and reached a peak maximum increase of 56.3 ± 0.4 nM following the response. However, due to the variability in dopamine release across all sites, post hoc tests did not reveal significant increases at specific time points relative to the response. A third set of NAc neurons (n = 9) displayed decreases in cell firing within seconds before and/or after the cocaine-reinforced lever press response (termed reinforcement-inhibition or RFi cells; Figure 4C). Note that since inhibitions occurred at varying times relative to the response across individual cells, only 5 of the 9 type RFi cells are shown in the average PEH. For those locations,
