LTP-like synaptic efficacy changes following electroconvulsive stimulation.

Synaptic plasticity is thought to represent a mechanism for memory formation. Memory disturbances commonly follow electroconvulsive therapy (ECT) for depression. Accordingly, we examined the development and duration of the effects of electroconvulsive stimulation (ECS) on hippocampal synaptic plasticity in rats. Daily recording of field potentials during 10 spaced ECS revealed an increase in the dentate gyrus evoked response, reaching a maximum after the fifth seizure. In a second experiment, an identical ECS series substantially reduced the degree to which electrically induced synaptic changes (long-term potentiation--LTP) could be elicited under anaesthesia for up to 40 days. These findings suggest that ECS induces LTP-like long-lasting synaptic changes which may underlie the neuropsychological sequelae of ECT treatment in humans.