Memory of electroconvulsive shock as a function of intensity and duration

Following multitrial active-avoidance training in a two-way shuttlebox, rats received a single electroconvulsive shock (ECS) of one of three intensities and six durations. Convulsed animals required more trials to relearn the task than they had taken in original learning, suggesting that ECS was an aversive stimulus. This effect first increased and then decreased with increasing ECS intensity. A similar, but weaker (p <.10), inverted U-shaped function was found for ECS duration. The inverted-U function is thought to be an interaction of the aversive stimulus properties and amnesic properties of ECS. The significance of memory of ECS surviving the amnesic properties of ECS is considered.