STUDIES ON THE REACTION OF A SINGLE MOTONEURON IN THE SPINAL CORD OF A TOAD TO ELECTRICAL STIMULATION

抄録

The excitability of a single motoneuron soma in a toad's spinal cord is compared with that of a single motor fibre from a experimental point of view.
The following is the results of the experiments.
(1) The strength-duration curve of the neuron soma is compared with that of the motor fibre; it is noticed that the rheobase of the neuron soma is lower and the chronaxie of it is longer than those of the motor fibre. The Weiss formula is acceptable in these two strength-duration curves.
(2) The neuron soma produces more easily multiple responses than the motor fibre by direct current stimulation; but the results obtained from single nervepreparation are not same in every case, and the author has grouped four types according to the character of multiple responses and the accommodation curve.
(3) The effect of the electrotonus on the neuron soma is different from that on the motor fibre.
(4) No differences of the latency are detectable between the neuron soma and the motor fibre.
(5) The relative refractory period of the neuron soma is shorter than that of the motor fibre; the refractoriness of the neuron soma is followed by the supernormal phase which is not recognized with the motor fibre under the same conditions.