Hypothermia-induced anterograde amnesia and its reversal in rats trained on a T-maze escape task

Previous studies have demonstrated anterograde amnesia (AA) and its reversal in rats trained on passive avoidance tasks. The present investigation was conducted to determine whether induction and/or reversal of AA is limited to inhibitory learning tasks or whether these phenomena can be illustrated in behavioral situations involving choice. Accordingly, in Experiment 1, rats were trained on a T-maze escape task as either hypothermic (28 degrees C) or normothermic. Twenty-four hours later half of each acquisition group was tested as either hypothermic or normothermic. Results indicated a stern retention decrement for animals trained at a lower body temperature and tested as normothermic. However, this prograde memory deficit was attenuated when animals were recooled shortly prior to testing. In an attempt to extend the phenomenon of memory recovery observed in Experiment 1, Experiment 2 examined whether pretest injections of d-amphetamine (0.5 mg/kg), a purported amnesia-attenuating agent, could lessen the AA induced by hypothermia. Amphetamine, at least at the dose used, did not reduce the memory impairment. Results are interpreted in terms of the state dependent nature of memory.