Figure 1.

Line graphs displaying operant and infusion data from rats included in the dendritic spine morphologic analyses. Rats underwent cocaine self-administration (SA cocaine) in daily 2 h training sessions for a minimum of 12 d using an FR1 schedule of reinforcement with a 20 s timeout. In addition, some rats were yoked to the SA rats and received noncontingent infusions of cocaine (yoked-cocaine) or saline (yoked-saline) or received a program of noncontingent infusions based upon previous operant behavior from SA cocaine rats. A, Infusions of cocaine (200 μg cocaine/infusion) or saline across the last 12 d of self-administration. Active (B) and inactive (C) lever presses across the last 12 d of self-administration. n = 15 yoked-saline; n = 15 yoked-cocaine; n = 22 SA cocaine.