Effects of electrotonus on the electrical activities of spinal motoneurons of the toad.

The method of intracellular potential recording made it possible to investigate the effect of electrotonus on the cellular activities more precisely than before, by using the membrane potential as a parameter. Many studies along this line thus appeared in succession with various kinds of tissues 1, 7,s,15,16'17,18,19,23,31) In the present paper, the results obtained with the spinal motoneurons of the toad will be described. Single intracellular microelectrodes in a bridge circuit were used for applying electric currents to the motoneuron and for the simultaneous recording of its response. This method, first introduced by ARAKI and OTANI1), has already been tried with modifications and discussed by many investigators6,10,11,12,13,17, 18, 30) and, in spite of a few disadvantages pointed out by some of them, has proved to be convenient and reliable, if sufficient caution is paid to its limitations.