TEMPORAL SUMMATION IN PERIPHERAL NERVE FIBERS

Abstract

A state in a single axis cylinder such that a single impulse, recorded with the electron oscillograph after amplification, will not be conducted, but impulses succeeding within about 100 msec. will, can be produced by anodal polarization and by Ca poisoning, and also occurs fortuitously in failing nerve. This temporal summation is referred to a change in the excitability of the blocked segment induced by the first response, which, though blocked, lowers the threshold beyond so that the next response reaches the threshold of, and is conducted through, the depressed area. Cathodal polarization and ether produce a state in nerve such that the second of 2 responses will not be conducted when the first is. By approximating the 2 stimuli under these circumstances it is possible to de crease the 2d spike in steps in a manner entirely comparable to the serial blocking of segments induced by increasing the intensity of depressing agents.