Yuki Sato (Master's student) and Professor Shu Morioka of the Graduate School of Kio University have shown that administering transcranial direct current stimulation to the cerebellum in healthy subjects sitting in a seated position has no effect on the excitability of spinal motor neurons or the vestibulospinal tract.
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that can modulate brain excitability and is thought to be effective in rehabilitation. It has been reported that tDCS to the cerebellum, an important brain region in motor learning and postural control, can modulate the activity of the cerebellar cortex, but its effects on the excitability of spinal motor neurons and vestibulospinal tracts that are functionally connected to the cerebellum were unknown.
Therefore, the research group used neurophysiological techniques (H-reflex and direct current vestibular stimulation (GVS) etc.) to examine the effect of tDCS to the cerebellum on the excitability of spinal motor neurons and the vestibulospinal tract. As a result, the excitability of spinal motor neurons and the vestibulospinal tract was not changed before, during, or after tDCS stimulation to the cerebellum. It was suggested that tDCS to the cerebellum in healthy subjects in a sitting position may not affect the excitability of spinal motor neurons and the vestibulospinal tract.
The results of this study may be related to the neurological mechanism of action of tDCS, which changes the membrane potential of neurons, and it is possible that modulating cerebellar activity by tDCS may not have much effect on the regulation of spinal motor neurons and vestibulospinal tract excitability in healthy subjects in the sitting position. In the future, it is necessary to investigate the involvement of the cerebellum in spinal motor neurons and vestibulospinal tract under different neuromodulation techniques and postural conditions.
