R. W. GERARD 29 



memories are feeble or abolished (Duncan, 194.S ; Gerard, [953 ; Ransmeier, 

 1954; Leukcl, 1957; Otis and Cerf, 1959). Thus, hamsters or rats trained in 

 grouped runs on some learning situation — a maze or an avoidance 

 conditioning or the like — show a normal learning curve if a convulsive 

 electroshock is delivered after each set of runs with an interval of 4 hours 

 or more. It the shocks follow the experience by an hour there is some 

 deterioration, at 1 5 minutes loss is very considerable, and at 5 minutes or 

 less learning is in effect prevented. If a hamster is promptly cooled after 

 the learning experience, a shock given an hour later can be as deleterious 

 as one given a few minutes later at body temperature; the Q^^ of the 

 fixation process has been thus determined at nearly three (Ransmeier and 

 Gerard, 1954). 



Anoxia acts much like electroshock, and the two sum their effects 

 (Ransmeier and Gerard, 1954; Thompson, 1957). A number of drugs has 

 now been tested for influences on the electroshock effect. Reserpine, like 

 anoxia, potentiates the ECS disruption of learning (Weyner and Reimonis, 

 1959); ether protects against electroshock effects (Seigel ct al, 1949; 

 Potter and Stone, 1947); and, in man, meprobamate decreases the con- 

 tusion produced following electroshock (Thai, 1956). Miss Rabc and I 

 (1959) have just completed studies of the action of phenobarbital and of 

 meprobamate on ECS action in rats on an avoidance conditioning test. In 

 effect, phenobarbital slows and prolongs the fixation time, as judged by 

 the greater disruptive effects of a convulsive stimulus at i, 2, 5 and 15 

 minutes in animals under the barbiturate as compared with undrugged 

 ones; while meprobamate, contrary to expectation, seems to have the 

 reverse effect. Interestingly enough, meprobamate, but not phenobarbital, 

 slows the learning process, aside from any ECS. Strychnine, according to 

 an informal communication from Dr Krech, shortens the fixation time; a 

 convulsive shock at a given time interval is less disruptive in the strychnized 

 rat than in one without the drug. 



The above facts fit well into a theory of continued activity in the nervous 

 system, following the arrival of sensory impulses, in the course of which a 

 dynamic memory is fixed as a structural one (Gerard, 1960a). Summation, 

 irradiation and reverberation of messages would lead to repeatec^ activity 

 of the same neurones, with progressively greater and greater residual 

 changes from the continued activity. At 50 reverberations per second, 

 100,000 actions could easily occur during the fixation time; presumably 

 sufficient to leave an indelible trace. 



Any change that would enhance the extent or intensity of reverberation 

 should hasten the fixation process; any agent acting in the converse 



