To examine whether differences exist in the relationship between dopamine release and NAc cell firing across the core and shell, measurements were separated according to NP and phasic cells, and the mean [DA] was plotted relative to the lever press (Figure 6). Examination of [DA]s at locations where only NP neurons were recorded revealed no significant increases in [DA] in the core (Figure 6A) or shell (Figure 6B); in fact a significant decrease in dopamine release was observed immediately following the response at shell locations. In contrast, when [DA] changes were plotted at sites in which only phasic (type PR, RFe and RFi) cells were recorded, significant increases in dopamine was observed in both the core (F13, 247 = 2.6, p < 0.0001, Figure 6C) and shell (F10, 190 = 31.7, p < 0.0001; Figure 6D). There were only four locations (two in the core and two in the shell) at which phasic cells were recorded and no significant changes in dopamine were observed (data not shown).
