200 



BC5I 



Information Storage and Neural Control 



pre. 



5 s. 



i".-^\^ 



let. 



\/v/\Ay\,^r^iPw^/^\Ar. 



9cps 



V^/v 



3cps 



Fig. 9. Same preparation and same electrode arrangement as in Figure 8. The 

 relevant section is labeled "B." A pre- and immediate post-tetanization stimulus 

 frequency of nine per second was shifted to three per second. As the response 

 "locks" in at three per second (last tracing) a series of inter-stimulus, regularly 

 spaced waves appear which seem to recapitulate the nine per second rhythm 

 For discussion, see text. Calibration: 100 microvolts and 100 milliseconds. 

 (Chow, K. L. and Dewson, J.: unpublished data.) 



are evenly spaced smaller potentials which seem to recapitulate 

 the earlier nine per second sequence. Is this the electrical expression 

 of the neural trace of nine per second? Unfortunately the experi- 

 ments are still too few to afford a confident answer. 



How, it may be asked, can these experiments with tetanization 

 be linked to the earlier studies on polarizing" currents? Although 

 measurements of the steady potential were not made in these 

 studies the inference is clear from the fact that tetanization is 

 effective across a solution of neural continuity that an alteration 

 of electrical field contours has occurred. Furthermore there is 

 abundant data from many laboratories to indicate the drastic 

 alterations of steady potential gradients accompanying tetanic 

 stimulation of this kind (7, 8, 9, 15, 16, 17, 18). 



