Retrograde Amnesia from Conditioned Competing Responses.

If electroconvulsive shock is given immediately after a learning trial, retrograde amnesia for that response occurs. The usual interpretation of such amnesia states that a neural engram, after a learning trial, requires a certain amount of time to consolidate, and electroconvulsive shock interferes with this consolidation, producing amnesia. Four studies are summarized which indicate that convulsive shock serves as an unconditioned stimulus producing a convulsive response, that takes precedence over other behavior, and part of which becomes conditioned to stimuli in the learning situation. The convulsive response competes with, and replaces, the previous response, resulting in the appearance of amnesia.