Intolerance to Noise in Psychiatric Disorders

is confounded by state-dependent passivity, as might be expected in the depressed state. In other words, if the animal remains passive in a passive avoidance task, we do not know whether the prolonged latency to response is due to depression-associated passivity or to better recall of a noxious stimulus. Thus, in passive avoidance tasks, passivity of the animal on account of depression related behaviour can falsely inflate task performance scores, and hence be misinterpreted as better recall. It is currently considered that in research involving learning and memory, such potential biases should be identified and eliminated at the level of the study design itself (Andrade et al., 2000). I.therefore suggest that authors' point might have been more validly made had they used an active avoidance task to demonstrate that inescapable shocks improve the recall of noxious stimuli. Finally : a healthy rat in a controlled environment is far removed from a dysfunctional human in a complex psychosocial milieu; therefore, generalization from laboratory to clinic should be made with caution, and only after artefactual influences have been eliminated through appropriate experimental designs (Andrade, 1995, Andrade et al.,2000).