Mean (±SEM) changes in electrochemical currents detected by Glu sensors after the iv saline injection (brown; n=8). The changes induced by the initial injection of cocaine (gray, n=9) are shown for comparison. There was a significant main effect between cocaine and saline (gray bar; 230 s/n=59, F1,15=4.55 p<0.05) or a significant Injection × Time interaction (black bar; 122 s, F31,465=1.48, p<0.05).