Effect of Electrotonus on Accommodation in Nerve

Abstract

Hill1 has proposed an approach to the response of excitable tissues involving two processes, one a rise of the “local potential” and the other a change of threshold called “accommodation”, the rates of which are represented by the time constants “κ” and “λ” respectively. Blair2 has pointed out some theoretical inadequacies arising from investigations of the effects of electrotonus on rheobase and chronaxie (theoretically .693k), but in the absence of similar studies on λ, the extent of such limitations is not clear. Consequently, the present investigation of λ was undertaken.The technic described by Solandt3 employing exponentially rising currents was used to determine the λ of the sciatic nerves of Rana pipiens. The same nonpolarizable electrodes, 2 cm apart, were employed to produce a 2-second electrotonus and to apply the exponential currents. Special precautions were taken to minimize residual and progressive effects. Most experiments were performed at 20°C.The chief results obtained are summarized in...