Alterations of exploratory patterns induced by uncontrollable shock.

A series of studies evaluated the effects of footshock on subsequent patterns of exploration in an eight-arm radial maze. When permitted to explore an eight-arm maze freely, mice typically exhibited a characteristic pattern of exploration in which they tended to enter arms of the maze that were least recently visited (spontaneous alternation). Moreover, animals frequently made successive entries into immediately adjacent arms of the maze (adjacent alternation). Following exposure to escapable shock the alternation performance is not appreciably altered; however, an identical amount of uncontrollable shock disrupted the adjacent alternation tendency. The disruption was evident immediately after shock, but was absent if mice were tested 24 hr after the inescapable-shock treatment. Interestingly, when mice were reexposed to a small number of shocks, a treatment which itself has no effect, the disturbance of adjacent alternation was reinstated. It is suggested that the alterations of exploratory patterns may be related to catecholamine alterations provoked by stressors, and that the behavioral disturbance could potentially influence performance in tasks involving associative processes.