The subthreshold potentials in a crustacean nerve fibre

Abstract

In a recent paper Katz (1937) has described a number of observations which are inconsistent with classical theories of excitation, but which may be explained by assuming that a subthreshold shock can elicit a small and localized action potential in the cathodic part of a nerve fibre. At first the assumption of a subthreshold response seems to be in conflict with the allor-nothing law, but there is in reality no contradiction, since the all-ornothing principle refers to the propagated disturbance, and does not exclude the possibility of graded reactions in the stimulated region. Indeed, the existence of some kind of subliminal action potential is to be expected from the local circuit theory of nervous transmission; for the current generated by the activity of a very short length of nerve would be too weak to excite surrounding regions, so that a shock which activated less than a certain length would fail to produce a self-propagating impulse and would leave behind only a small and localized response (cf. Rosenberg 1937, Rushton 1937).