Neuronal mechanisms of increased accessibility of unpleasant memories in helpless rats - a summary of present findings and implication.

Several studies in humans have indicated an association between enhanced retrieval of unpleasant memory and depressive moods. No analogy has so far been demonstrated in laboratory animals, however. A series of z-tperiments, therefore, was initiated in this laboratory with an aim to develop an analogous model of memory bias and to define the neuronal substrate that may account for the differential memory bias, in rats. This paper summarizes current results of these experiments and discusses the likely neuronal mechanism of the enhanced retrieval of unpleasant memories. Also, the implications of these experimental data in understanding the psychobiologicai aspects of "emotive biasing", so characteristics of human conditions like depression and post-traumatic stress disorders are discussed.