Fig. 1.
Within-session tolerance of the extracellular DA response to self-administered cocaine in four different rhesus monkeys (M103, M32, M49, and M47), with responses collapsed across all striatal subdivisions. Initial studies were done in animal M103 with 10 min collection times, after which, for greater temporal detail, a 2 min sampling procedure was used. For animals M49 and M47, a time offset to compensate for dead volume in the outflow lines was incorporated; thus, the temporal pattern of the dopaminergic response for them is the most accurate. Cocaine was self-administered at t = 0. The second self-administration occurred 100 min after the first in the same session. Solidcircles represent the first injection; opencircles represent the second injection. The number of trials is as follows: M103,n = 4; M32, n = 5; M49,n = 14; M47, n = 9.