Evidence that electroconvulsive shock alters memory retrieval rather than memory consolidation

ECS-induced amnesia: Retention function consistent with state dependency predictions

“…ECS Ss did not approach the level of retention demonstrated by the controls at any tested interval in the present experiment. Also, others, finding spontaneous memory recovery by testing independent groups of ECS Ss at various intervals, have obtained less than complete recovery (e.g., Cooper & Koppenaal, 1964;Kohlenberg & Trabasso, 1968) or, in cases of statistical equivalence between the ECS groups and controls, the use of some form of cut-off procedure at the test obviates any conclusions concerning the completeness of the memory recovered in ECS Ss (e.g., Nielson, 1968;Pagano, Bush, Martin, & Hunt, 1969).…”

“…In general, this hypothesis has received strong experimental support (Galluscio, 1971;Lewis, Misanin, & Miller, 1968;Miller & Springer, 1972;Quartermain, McEwen, & Azmitia, 1970). The other notion, the state dependency hypothesis (De Vietti & Larson, 1971;Mayse & De Vietti, 1971 ;Nielson, 1968), holds that amnesia results from an altered brain state induced by the interaction of ECS with the training-trial footshock. This hypothesis, .…”

“…However, the evidence that the state dependency effect acts to influence the amnesia induced in the typical ECS paradigm, i.e., when ECS follows a training trial footshock, is less than compelling. While some have obtained spontaneous memory recovery under these circumstances (e.g., Cooper & Koppenaal, 1964;Kohlenberg & Trabasso, 1968;Nielson, 1968;Young & Galluscio, 1971) Greenough, Schwitzgebel, & Fulcher, 1968;Herz & Peeke, 1967;Luttges & McGaugh, 1967). Even when parameters have been carefully adjusted to maximize the effect (DeVietti et al, 1973; DeVietti & Hopfer, in press b), little more than nonsignificant trends toward memory recovery have been obtained.…”

Effects of halothane anesthesia on the retention of a passive avoidance task in rats

“…For example, Lewis, Miller, & Misanin (1968) found that seemingly lost memories of step-down a v 0 i dance training could be "returned" to memory be using simple "reminder" shocks before retesting. Nielson (1968) has offered another explanation of the RA effect in terms of brain excitability states, with no reference to memory consolidation. There is evidence that, when the brain excitability level is reduced, CRs conditioned at the original level may be lost (Kawakami & Sawyer, 1964).…”

“…Thus, the problem is, ostensibly, one of retrieval, not storage. To test the theory, Nielson (1968) applied ECS before, as weil as after, training. Consequently, brain excitability levels should have been elevated during both learning and testing.…”