Although the concept that information processing continues following the termination of a learning trial has long been represented in human research (e.g., "rehearsal"), it has only recently gained ac­ knowledgement in studies of animal memory. An in­ fluential paper by McGaugh (1966) provided an im­ portant impetus in this direction by reviewing evi­ dence that various posttrial manipulations could modulate retention. Thus, electroconvulsive shock (BCS) after training impaired memory, whereas strychnine administration enhanced it. Although McGaugh's (1966) specific interpretation was linked to a consolidation model of memory, the more gen­ eral impact of his analysis may have been in calling attention to phenomena implying that the processing of information continues after the events constituting the nominallearning episode have ended. The notion of postacquisition processing has come to furnish a frame of reference for a variety of studies of animal memory (e.g., directed forgetting­ Maki & Hegvik, 1980, and Stonebraker & Rilling, 1981; memory counterconditioning-Richardson, Riccio, Jamis, Skozcen, & Cabosky, 1982; priming­ Wagner, 1978; posttrial surprise-Wagner, Rudy, & Whitlow, 1973), but our presentation here will con­ centrate on a phenomenon that has been particularly weIl established, namely, experimentally induced retrograde amnesia (RA). In this paper we consider some of the data that demonstrate that postacquisi­ tion traumatic insult can produce profound memory losses. But we will also suggest that these retrograde amnesias are not attributable to disruption or failure of the storage process. Rather, the memory loss ap­ pears to be linked to the lack of appropriate cues for retrieva1. It is in this respect, then, that memory can

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The status of memory following experimentally induced amnesias: Gone, but not forgotten

Persistent but modifiable retrograde amnesia produced by hypothermia

Fear and punishment as determinants of passive-avoidance responding.

The effects of cooling on associative learning and memory processes in Caenorhabditis elegans were investigated by giving the worms cold shock at various times before or after conditioning. A pretraining cold shock in the 30 min immediately before conditioning and a posttraining cold shock in the 30 min immediately after conditioning both disrupted learning and memory processes tested a short time after conditioning. However, if tested 3 hr after conditioning, worms given a pretraining cold shock demonstrated learned preferences, whereas worms given a posttraining cold shock still had memory deficits. These results suggest that the effects of cold shock on associative learning and memory can be dissociated into effects on memory retrieval and memory retention.

Cold shock before associative conditioning blocks memory retrieval, but cold shock after conditioning blocks memory retention.

In two experiments, hypothermia produced retrograde amnesia (RA) for passive avoidance and induced paroxysmal spike discharges in cortical EEC Weak doses of strychnine had no apparent effect on behavior but hastened onset of brain seizures during cooling. Hypothermia appears to produce RA by inducing brain seizures similar to those elicited by ESB.

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Paula Cohen

Papers

Some behavioral aspects of retrograde amnesia produced by hypothermia