EFFECTS ON BIOELECTRIC ACTIVITY OF NERVES 



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Fig. 13. Relative conduction velocity of giant nerve fiber impulse under UV irradi- 

 ation, plotted as a function of time of irradiation, as in Fig. 12. 



on the graph, since for stable nerves the vakie did not deviate significantly, 

 once the nerve had settled on the electrodes and the initial period of insta- 

 bility had passed. The relative activity represents the ratio of the refractory 

 period in milliseconds at the beginning of irradiation to the refractory period 

 in milliseconds at any designated time. This inverse relationship is used 

 because a decrease in refractory period connotes an increase in responsive- 

 ness of the nerve. Hence, a rise in the curve indicates an enhancement of 

 activity of the nerve. Figure 16 shows the same twofold effect observed 

 previously — an almost immediate enhancement of activity, followed by an 



