| Abstract: | Experiments are reported which show that 2 mg/kg of d-amphetamine sulfate injected intravenously immediately after footshock on a one-trail passive aviodance learning task impairs the performance of mice in retention tests 24 and 96 hr late. When the injection is delayed by as little as 90 sec, no such impairment is seen. A similar intravenous injection immediately after the learning trail of a water-rewarded one-trail appetitive task has no discernible affect on performance in retention trails 24 hr and 6 wk later. It is argued that the effects of the amphetamines on learning behavior depend on whether reward or punishment is involoved and, further, that all such effects could be accounted for in terms of the drugs' influence on memory mechanisms. |
