Chunk #22 — Results — Differential dopamine release dynamics in the core versus shell relative to cocaine-reinforced responding during self-administration
Although dopamine levels in the shell also increased relative to lever press responding for intravenous cocaine, the profile of those changes differed from that observed in the core across all shell recording sites (Figure 2B). Specifically, a pronounced and relatively prolonged increase in [DA] began approximately 8 s preceding the response followed by a slight decline at response completion (mean pre-response maximum increase was 27.2 ± 7.9 nM). This was followed by a larger increase in [DA] that began approximately 2 s following the response and peaked at 52.1 ± 4.9 nM approximately 6 s after the operant response. This post-response increase in [DA] remained elevated for approximately 9 s. A one-way analysis of variance (ANOVA) revealed significant fluctuations in [DA] in the shell relative to the lever-press response (F19, 171 = 4.819, p < 0.001). Dunnett’s multiple comparison test revealed that dopamine concentrations were significantly (p < 0.05) elevated relative to baseline 2 to 3 s prior to the response and during 1 to 8 s following response completion.
