Muscle-afferent projection to the sensorimotor cortex after voluntary movement and motor-point stimulation: an MEG study.
OBJECTIVE
To investigate the projection of muscle afferents to the sensorimotor cortex after voluntary finger movement by using magnetoencephalography (MEG).


METHODS
The movement-evoked magnetic fields (MEFs) after voluntary index-finger extension were recorded by a 204-channel whole-head MEG system. Somatosensory-evoked magnetic fields (SEFs) were recorded after motor-point stimulation was applied to the right extensor indicis muscle by using a pair of wire electrodes.


RESULTS
The MEF waveforms were observed at 35.8±9.7 ms after movement onset (MEF1). The most concentrated SEFs were identified at 78.7±5.6 ms (M70), and the onset latency of M70 was 39.0±5.5 ms after motor-point stimulation. The mean locations of the equivalent current dipoles (ECDs) of MEF1 and M70 were significantly medial and superior to that of N20m elicited by median-nerve stimulation. The ECD locations and directions of both MEF1 and M70 were concordant in the axial, coronal and sagittal planes.


CONCLUSIONS
MEF1 and M70 might be elicited by muscle-afferent feedback following muscle contraction. In addition, these ECDs may be located in area 4.


CONCLUSIONS
Motor-point stimulation is a useful tool for confirming the projection of muscle-afferent feedback to the sensorimotor cortex after voluntary movement.
Onishi
Hideaki
H
Niigata University of Health and Welfare, Niigata 950-2181, Japan. Electronic address: onishi@nuhw.ac.jp.
Oyama
Mineo
M
Niigata University of Health and Welfare, Niigata 950-2181, Japan.
Soma
Toshio
T
Niigata University of Health and Welfare, Niigata 950-2181, Japan.
Kirimoto
Hikari
H
Niigata University of Health and Welfare, Niigata 950-2181, Japan.
Sugawara
Kazuhiro
K
Niigata University of Health and Welfare, Niigata 950-2181, Japan.
Murakami
Hiroatsu
H
Nishi-Niigata Chuo National Hospital, Niigata, Japan.
Kameyama
Shigeki
S
Nishi-Niigata Chuo National Hospital, Niigata, Japan.
D000328:Adult; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D055815:Young Adult