Supplementary Figure 5: Effects of cocaine (pharmacological) and responding for cocaine delivery (behavioral) vary with access regimen (ShA/LgA) and intake pattern (Esc/Non-esc).
From: Excessive cocaine use results from decreased phasic dopamine signaling in the striatum
a, Average increases in extracellular concentration of dopamine in the VMS over a thirty-second period following a non-contingent (response-independent; no CS) intravenous infusion of cocaine (0.5 mg/kg) are depicted for non-escalated (closed bars) and escalated (open bars) animals (mean + SEM) given ShA (left) or LgA (right). Cocaine-induced dopamine release in the VMS was significantly decreased in rats given LgA compared to ShA, but release did not differ significantly between non-escalated and escalated rats (P>0.05). b, Phasic dopamine in the VMS of non-escalated animals (n = 6/16) in the third week of LgA was not different to that of non-escalated ShA rats (n = 10/16). Escalated ShA animals (n = 6/16) displayed a non-significant trend for decreased VMS dopamine compared to non-escalating ShA rats (n = 10/16); #P = 0.094). Escalated LgA animals exhibited less dopamine release than escalated ShA animals. Data are mean+SEM. *P<0.05, **P<0.01.
