368 Information Storage and Neural Control 



arily pretty well out when asymmetry appears. Before that, presum- 

 ably, impulses coming down the cord have not been effective. 



E. Roy John (Rochester, New York): I would like to mention a 

 couple of experiments related to your remarks and ask if you 

 would react to them. I ain sure the first one will be of interest 

 to you, although it is not directly related to the question of memory 

 in the nervous system, but rather to your comments on the loss 

 of plasticity and functional specialization in tissue. The data are 

 contained in a recent paper by Buchsbaum in the Journal oj 

 Experimental ^oology. He and his co-workers were trying to develop 

 a planarian tissue culture inethod, and succeeded in making a 

 pleasantly simple medium in which explants were grown. They 

 observed that a small explant occasionally proliferated as a sheet, 

 reached a certain size, folded back on itself, apparently dedifferenti- 

 ated, and developed into a planarian. This rather unexpected 

 observation suggests that, at least at this level, the loss of plasticity 

 with specialization is reversible. 



More directly relevant to our major concern here is the recent 

 paper by Sporn and Dingman in the Journal of Psychiatric Research 

 in which 8-azaguanine was used to interfere with RNA synthesis, 

 and a significant decrease in the rate of maze learning was ob- 

 served. I would also like to mention the on-going thesis work of 

 Eugene Sachs, in our laboratory, which may provide additional 

 insight into aspects of information storage. 



Some time ago, in collaboration with Wenzel and Tschirgi, we 

 observed that small intraventricular injections of electrolytes seri- 

 ously interfered with the performance of some previously estab- 

 lished conditioned responses. Mr. Sachs has investigated the effects 

 of small alterations in central potassium or calcium on learning 

 and performance by making intraventricular injections before 

 each training session. Control groups are first trained, and then 

 receive an appropriate number of central injections. Sachs' results 

 indicate that animals perform conditioned responses best under 

 conditions of central electrolyte concentration like those present 

 during training and poorly under other conditions, including 

 normal cerebrospinal fluid concentration. Control groups that 

 receive the injections after training show no evidence of accom- 

 modation effects. In these animals, central injection causes per- 



