EXPERIMENTAL ANALYSIS OF THE SIMPLE ACTION POTENTIAL WAVE IN NERVE BY THE CATHODE RAY OSCILLOGRAPH

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Abstract
Both the simple action potential wave in the phrenic nerve (dog) and constituent waves (alpha, beta, gamma, etc.) in the sciatic action potential (Rana catesbiana and Rana pipiens) are composed of axon action potentials traveling at different rates in individual component fibers, as proved by the following observations. The waves diminish in height and broaden as they move from the point whence they are started by an induction shock; but despite this change in form the area of the waves, amount of current in them, and position of the end of the absolutely refractory phase relative to the beginning of the conducted action potential remain constant. On the other hand the beginning of the absolutely refractory phase coincides with the beginning of the action potential only at the site of the initiating stimulus. In the action potential at a distance from the site of stimulation the absolutely refractory phase is later than the start of the action potential by an interval that is determined by the lag of the start of slowest moving axon wave behind the fastest. By causing 2 action waves, each consisting of the alpha process only, but started by stimuli of 2 different strengths both short of maximal, to travel toward each other, a type of blocking is obtained that can be accounted for only if the fibers participating in the alpha process differ among themselves in respect to irritability; and configuration of the resulting action waves is such as to indicate that the less irritable the fiber the slower is the rate with which it conducts its action wave. And finally it is found that fibers contributing to the simple action wave differ among themselves in respect to utilization periods. The time constants of axon potential waves seem to be approximately alike in all fibers, the time to maximum and the duration measuring, respectively, in bullfrog''s sciatic at room temp., 0.4+ and 1.4+ sigma, and in the dog''s phrenic at body temp., 0.24[plus or minus] and 0.7+ sigma; but nearly all of the experimental data derived from the study of the alpha wave in the sciatic nerve of the bullfrog are consistent with conclusions reached by inference through analysis of a diagram constructed of axon waves having a time to maximum of 0.3 and a duration of 0.9 sigma, and traveling at uniformly distributed rates ranging between 42-30 or 27 m.p.s., indicating that the slow initial rise and terminal fall of potential contribute relatively little to the summed effect of all of the axon potentials. If there is any measurable spread of potential ahead of the refractory region under the propagated axon action wave it does not exceed 0.07 sigma in duration or 2.9 mm. in length, when the action potential wave is traveling at the rate of 42 m.p.s. Additional evidence is given indicating that instrumental distortion of the amplified action potential is within the limit of error of measurement of the records.

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