Electroconvulsive shock-induced retrograde amnesia: An analysis of the variation in the length of the amnesia gradient

Recent evidence indicates that the amnesia gradient produced by post-training electroconvulsive shock is not constant but highly variable. This result provides a considerable problem for consolidation theory. To account for this data, an elaboration of the original idea seems necessary. In this paper, we examine the evidence on the length of the consolidation gradient and find that two variables, task characteristics and electroshock parameters, seem to contribute most to the variation in the amnesia gradient found following electroconvulsive shock. From our point of view, task variables may have to do with the rate of information consolidation, while electroshock variables may directly determine how severely consolidation might be disrupted. A consolidation theory along these lines can account for much of the literature on electroconvulsive shock-produced interference with retention, including the recent findings of diminished amnesia over time, the effect of reminder footshock and the results with repeated training-electroshock trials.