Figure 3. Methylphenidate modulates response inhibition in adults but not in adolescents.

A. In adults, methylphenidate had dose dependent effects on response inhibition. Low dose methylphenidate (.3 mg/kg) caused a trend toward increased ability to withhold a response, mid dose (1 mg/kg) did not alter behavior, and high dose (3. mg/kg) impaired the ability to withhold a response. There were no effects of any dose methylphenidate in adolescents. A drug X age interaction revealed that the age groups statistically responded differently to methylphenidate. Note that, as in Figure 2A, there were no baseline differences between age groups in response inhibition under saline treatment. B. Methylphenidate had no effects on omitted trials in either adults or adolescents. Note that, as in Figure 2B, an age-related difference in omissions was evident in rats treated with saline. C. Methylphenidate did not affect latency to respond after the response inhibition tone. Adolescents showed increased response latency compared to adults with saline treatment, as in Figure 2B.