Somatosensory-evoked magnetic fields following stimulation of the tongue in humans.
OBJECTIVE
To clarify the characteristics relating to the temporal dynamics of the tongue primary somatosensory cortex (SI).


METHODS
We fabricated individual intraoral devices and recorded somatosensory-evoked magnetic fields (SEFs) from 10 normal subjects. The tongue was stimulated with a concentrated bipolar electrode in four areas: the right and left antero-lateral margins, and the right and left postero-lateral margins.


RESULTS
The primary component was recorded about 19 ms post-stimulation. Six components, termed 1M, 2M, 3M, 4M, 5M, and 6M, respectively, were found within 130 ms of the stimulation. These activities were detected in hemispheres both contralateral and ipsilateral to the stimulation, and were estimated to be located around the tongue SI. In addition, the latency of the contralateral hemisphere was significantly shorter than that of the ipsilateral hemisphere for all components, independent of the area stimulated.


CONCLUSIONS
Tactile stimulation of the tongue-elicited activity in the tongue SI in both hemispheres.


CONCLUSIONS
This is the first study to investigate the brain responses evoked by stimulating different areas of the tongue, using magnetoencephalography.
Sakamoto
Kiwako
K
Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, Japan. kiwakos@nips.ac.jp
Nakata
Hiroki
H
Kakigi
Ryusuke
R
D000328:Adult; D000704:Analysis of Variance; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D004566:Electrodes; D004569:Electroencephalography; D004574:Electromagnetic Fields; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008475:Median Nerve / Q000502:physiology; D010812:Physical Stimulation; D013003:Somatosensory Cortex / Q000502:physiology; D014059:Tongue / Q000294:innervation / Q000502:physiology*