Neuromagnetic somatosensory responses to natural moving tactile stimulation.
OBJECTIVE
To explore the somatosensory cortical responses to natural moving tactile stimulation in adult subjects using magnetoencephalography.


METHODS
We measured cortical somatosensory magnetic evoked fields (SEFs) to moving tactile stimuli by a brush over the right thumb once every 1.5 s in seven subjects. Electric SEFs with various intensity or simulated jitter were used for comparison.


RESULTS
Tactile SEFs in primary somatosensory cortex (SI) consisted of two deflections: N24mT and P55mT. Electric SEFs consisted of N24mE, P30mE, P40mE, and P55mE. The amplitude of N24mT was only 34% +/- 12% of N24mE, whereas P55mT and P55mE were of about the same size. With increased jitter or decreased intensity, attenuation of electric SEFs was more clearly found in early deflection than late deflection.


CONCLUSIONS
Natural moving tactile stimulation produced simpler cortical somatosensory waveforms in comparison with electric SEFs, partly related to less sharp intensity and stimulation jitter with moving tactile stimulation. We propose that of all the afferent fibers conveying the early deflection, the low threshold components participate the generation of the late deflection.
Lin
Yung-Yang
YY
Integrated Brain Research Unit, Department of Medical Research and Education, and Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
Kajola
Matti
M
D000328:Adult; D004558:Electric Stimulation; D004585:Electrooculography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006225:Hand / Q000294:innervation / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010812:Physical Stimulation; D013003:Somatosensory Cortex / Q000502:physiology*; D013933:Thumb / Q000294:innervation / Q000502:physiology; D014110:Touch / Q000502:physiology*