Abstract
1) Dendritic activities of spinal motoneurons in infant pigs and adult rabbits were studied intracellularly in acute experiments.
2) The motoneuron of the normal infant pig showed all-or-none potentials of 1-5 mV in amplitude and 2-6 ms in duration. Because of the multiplicity in waveform, they were ascribed to the dendrites.
3) The motoneuron of the normal rabbit did not exhibit dendritic spikes, but that of the rabbit with chronic stimulation to the L7 dorsal root showed dendritic spikes whose amplitude was less than 9 mV and duration more than 2 ms. The chronically stimulated motoneuron showed no signs of chromatolysis.
4) The discovery of dendritic spikes in the motoneuron suggested the functional importance of the dendrites.
