208 Information Storage and Neural Control 



2) There is no significant difference in performance between 

 any one of the polarization concUtions (except visual 

 cathode) and any other. 



3) Performance on the day JoUowing visual cathodal polari- 

 zation differs from that on the day preceding it at the 1 

 per cent level. 



4) There was no significant difference between performance 

 on the day following visual cathodal polarization and the 

 day after a break in training. 



5) Comparison of performance on the day after visual anodal 

 polarization with that on the day preceding (visual, 

 anodal) polarization yields a difference significant at 

 better than 1 per cent level of confidence. 



With respect to the last "conclusion'' listed, one must hasten 

 to add that there is no justification for attributing the improve- 

 ment to an effect of anodal polarization. The difference may 

 simply reflect the rising learning curve or the gain normally 

 expected in two days of practice. Only if the experiment were 

 performed at a point on the learning curve where the gain to be 

 expected in two days of practice was negligible could one attribute 

 the change to the neurological intervention. Such was not the 

 case in these experiments and therefore the influence (if any) of 

 anodal polarization of the cortical receiving area for the conditional 

 signal remains uncertain. 



In summary, it is clear that the imposition of a surface negative 

 potential gradient, along the axis of the main neural elements 

 of the cortical receiving area for the conditional signal, interferes 

 with conditioned performance and prevents retention of the 

 experience acquired during such polarization. Although the evi- 

 dence is much less conclusive it seems possible that surface positive 

 currents, while not producing any improvement in performance, 

 may lead to increased retention of the information transmitted 

 during the period of current flow. These last experiments lend 

 some support to the notion that the electrophysiological changes 

 secondary to imposed potential gradients, illustrated in the previous 

 studies, may have behavioral significance and may be relevant 

 to the manner in which the central nervous system achieves short- 



