Experimental induction of retrograde and anterograde amnesia concurrently: An animal model

In the clinical literature on memory dysfunction, the presence of both retrograde (RA) and anterograde (AA) amnesia due to acute trauma are commonly described. There has been, however, virtually no report of concurrently induced RA and AA using experimental procedures. In this study, we used two orthogonal tasks to examine the retrograde and anterograde impact of a single experimental insult. In Experiment 1, rats exposed to cold (hypothermia treatment) following consumption of a novel flavor, but prior to punishment training, showed impaired performance on later tests for attenuation of neophobia (retrograde task) and passive avoidance (anterograde task). The retrograde impairment was found to be time-dependent (Experiment 2) and independent of punishment effects (Experiment 3), indicating that both the retrograde and anterograde effects were based on memory loss. Therefore, it appears that RA and AA can be experimentally induced concurrently by a single traumatic insult. Thus, these findings provide an empirical model for comparing the characteristics of RA and AA when induced either independently or concurrently.