Figure 10.

Types of neuronal responses to repeated amphetamine during instrumental responding task. A, B, Based on sustained changes in firing rate (see Materials and Methods), neuronal responses to treatment were divided into increase, decrease, or no change responses. The distribution of different response types induced by vehicle or days 1, 3, 5, or challenge (Chal) of amphetamine are compared in mPFC (A) and OFC (B). χ² test showed a significant change in the distribution of responses to day 1 amphetamine compared with vehicle (mPFC, χ² = 55.05, p < 0.001; OFC, χ² = 52.52, p < 0.05). The proportions of decrease responses in mPFC and increase responses in OFC were significantly enhanced on days 5 and challenge compared with day 1 (mPFC, day 5, χ² = 12.24, p < 0.01; challenge day, χ² = 13.87, p < 0.001; OFC, day 5, χ² = 6.50, p < 0.05; challenge day, χ² = 7.56, p < 0.05).