EFFECT OF ELECTROCONVULSIVE SHOCK DURATION ON GRADIENT OF RETROGRADE AMNESIA

Rats trained in a one trial passive avoidance task received a single 100 mA electroconvulsive shock (ECS) of either 200 msec or 800 msec duration at various intervals following footshock. The resultant amnesic gradient was not significantly altered by the four-fold increase in ECS duration. The results confirm earlier findings that (a) the ECS susceptible phase of memory fixation lasts but a few sec and (b) the maximal effective punishment-ECS interval to produce retrograde amnesia cannot be extended by increasing the intensity of ECS. The data support a previous conclusion that the different amnesic gradients produced by ECS and carbon dioxide gas, in the same learning situation, probably reflect effects on different phases of short term memory fixation. © 1969.