Evidence supporting the memory disruption hypothesis of electro-convulsive shock action

A double foot-shock paradigm is used in a situation involving both passive avoidance and discriminated avoidance, and amnesia was observed when ECS followed seconds after training, in accord with the retrograde amnesia hypothesis.

Abstract

Electroconvulsive shock (ECS) following training is known to disrupt performance on passive avoidance tasks. The effect is usually seen as evidence that ECS produces retrograde amnesia. Recently it was reported that if passive avoidance training was followed by a second footshock (FS) several hours after training, and then ECS, impaired avoidance was shown on subsequent testing. This was interpreted as showing that the training-ECS interval is not crucial, thus questioning the retrograde amnesia hypothesis. Our repetition of the double foot-shock studies, however, failed to replicate these observations. We did notice that the second FS made animals hyperactive, suggesting that this is not an appropriate procedure in passive avoidance studies. We then used a double foot-shock paradigm in a situation involving both passive avoidance and discriminated avoidance. The experimental animals moved more rapidly, but displayed no amnesia in their choice behavior. Amnesia was observed when ECS followed seconds after training. The results are in accord with the retrograde amnesia hypothesis.