BERRY— HINSEY: RECOVERY, REGENERATING NERVES 551 



An accurate method of determining the conduction velocities of the 

 most rapidly conducting fibers is illustrated in figure 1. Several 

 records were taken along a regenerating nerve at various conduction 

 distances, and either the stimulating or the recording electrodes were 

 placed at a fixed point along the nerve. Then the other electrodes were 

 moved stepwise, to provide a greater conduction distance for each suc- 

 cessive record. Thus, in figure 1, the stimulating electrodes were 

 placed 4.6 cm. distal to the suture, and the pair of recording electrodes 

 was placed at a variety of points both distal and proximal to the 



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Conduction time - msec. 



1.5 



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 — 8 end 



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) Suture 



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■^^ Distal 

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Figure 1. Graph of conduction distance against conduction time of the action potentials, from 

 a saphenous nerve, 58 days after suture. The diagram on the right sliows that the stimulating 

 electrodes were held stationary on the distal stump, while the recording electrodes were moved. 

 The conduction velocity jumped from 23 m./s. in the distal stump to 50 m./s. in the central stump. 

 (Berry, Grundfest, & Hinsey.') 



suture. At each distance, a record was taken, and the conduction time 

 was measured between the shock and the initial rise of the spike. When 

 this time was plotted against conduction distance, as in figure 1, the 

 slope of the line indicated the maximum conduction velocity. 



The change in the slope of the line, in figure 1, occurred at the suture 

 line which shows that the distal outgrowths conduct more slowly than 

 their parent fibers in the central stump. The actual velocities from this 

 saphenous nerve, 58 days after suture, were 23 m.p.s. distal to the 

 suture, and these same fibers central to the suture conducted at 50 

 m.p.s. The continuity of the plotted line and its straight contour cen- 

 tral to the suture demonstrates that the change in velocity was recorded 

 from identical fibers on both sides of the suture. 



Assuming that conduction velocity is related to the fiber diameter, 

 the electrical method proves that the small fibers of the distal stump 

 are not the result of a selective ability of only the small fibers of the 



