Role of body temperature in the onset of, and recovery from, hypothermia-induced anterograde amnesia

The onset of, and recovery from, hypothermia-induced anterograde amnesia in rats was examined in two experiments. The first experiment demonstrated that recooling subjects shortly prior to testing alleviated anterograde amnesia. However, this recovery of memory was found to be temperature dependent: Subjects recooled and tested at 29δC, the temperature at training, demonstrated recovery, whereas subjects allowed to rewarm to 33δ did not. The role of core body temperature in the onset of anterograde amnesia was examined in Experiment 2. Animals were tested 30, 120, 360, or 1,440 min after one-trial punishment training. Subjects tested after 30 min were significantly cooler than the other subjects and exhibited good retention, whereas subjects tested after 360 or 1,440 min did not. Thus, although the onset of hypothermia-induced retrograde amnesia has been found to be temperature independent, onset of anterograde amnesia appears to be more closely linked to the subject’s temperature. The similarity between anterograde amnesia and the more traditional state-dependent retention paradigm is discussed.