ISSN:
1432-2013
Keywords:
Differential Blocking
;
α Motor Fiber
;
γ Motor Fiber
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Differential blocking of α motor fibers was investigated in single fiber recordings when slowly rising direct current was applied to the gastrocnemius nerve in the cat. 18 out of the 26 (69.2%) L7 ventral root filaments, each of which contained 2–5 single α, or γ motor fibers, or both, showed consecutive blocking from thicker to thinner fibers with increase of polarizing current. In the remaining 8 filaments (30.8%) thicker and thinner fibers were blocked almost simultaneously, or the order was reversed. The relation between the strength of the blocking current and conduction velocity is summarized on 30 α and 41 γ fibers. The blocking current of each single fibers was shown to be inversely proportional to 2.01 power of conduction velocity (correlation coefficient −0.71). A regression line was also drawn for α fibers alone, its correlation coefficient being −0.60. Concerning prolongation of latencies of 82 single fibers (39 α and 43 γ), it was shown that the faster the conduction velocity, the smaller was the prolongation of latencies. In no experiments did the prolongation of latencies of single α fibers exceed the latency range of the mass α volley. Moreover, single α fibers were blocked earlier than or almost simultaneously with the mass α volley.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00587220
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