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.

[1]  C. C. Wood,et al.  Human cortical potentials evoked by stimulation of the median nerve. I. Cytoarchitectonic areas generating short-latency activity. , 1989, Journal of neurophysiology.

[2]  J. Sarvas,et al.  Mixed and sensory nerve stimulations activate different cytoarchitectonic areas in the human primary somatosensory cortex SI , 1986, Experimental Brain Research.

[3]  R. Ilmoniemi,et al.  Magnetoencephalography-theory, instrumentation, and applications to noninvasive studies of the working human brain , 1993 .

[4]  I Hashimoto,et al.  Somatosensory evoked potentials elicited by air-puff stimuli generated by a new high-speed air control system. , 1987, Electroencephalography and clinical neurophysiology.

[5]  D. Mostofsky,et al.  Somatosensory evoked responses elicited by corneal and nostril air puff stimulation. , 1972, Electroencephalography and clinical neurophysiology.

[6]  O. Franzén,et al.  Evoked response correlates of psychophysical magnitude estimates for tactile stimulation in man , 2004, Experimental Brain Research.

[7]  J. Kaas,et al.  Multiple representations of the body within the primary somatosensory cortex of primates. , 1979, Science.

[8]  R. Hari,et al.  Magnetoencephalography in the study of human somatosensory cortical processing. , 1999, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[9]  J. Huttunen.  Effects of stimulus intensity on frontal, central and parietal somatosensory evoked potentials after median nerve stimulation. , 1995, Electromyography and clinical neurophysiology.

[10]  S. Jones,et al.  Scalp topography of human somatosensory evoked potentials: the effect of interfering tactile stimulation applied to the hand. , 1984, Electroencephalography and clinical neurophysiology.

[11]  Riitta Hari,et al.  Differential Effects of Muscle Contraction from Various Body Parts on Neuromagnetic Somatosensory Responses , 2000, NeuroImage.

[12]  I. Hashimoto,et al.  Somatosensory evoked potential correlates of psychophysical magnitude estimations for tactile air-puff stimulation in man , 2004, Experimental Brain Research.

[13]  J E Desmedt,et al.  The cognitive P40, N60 and P100 components of somatosensory evoked potentials and the earliest electrical signs of sensory processing in man. , 1983, Electroencephalography and clinical neurophysiology.

[14]  J. Kaas.  The Organization of Somatosensory Cortex in Primates and Other Mammals , 1984 .

[15]  E P Gardner,et al.  Somatosensory evoked potentials (SEPs) and cortical single unit responses elicited by mechanical tactile stimuli in awake monkeys. , 1984, Electroencephalography and clinical neurophysiology.

[16]  Y Toyokura,et al.  Somatosensory evoked responses to tactile tap in man. , 1973, Electroencephalography and clinical neurophysiology.

[17]  M Hämäläinen,et al.  Somatosensory evoked cerebral magnetic fields from SI and SII in man. , 1984, Electroencephalography and clinical neurophysiology.

[18]  N Forss,et al.  Effects of stimulus intensity on signals from human somatosensory cortices , 1998, Neuroreport.

[19]  M Schieppati,et al.  Short-latency cortical potentials evoked by tactile air-jet stimulation of body and face in man. , 1984, Electroencephalography and clinical neurophysiology.

[20]  L. Kaufman,et al.  Somatotopic organization of the human somatosensory cortex revealed by neuromagnetic measurements , 2004, Experimental Brain Research.

[21]  V. Mountcastle,et al.  Some aspects of the functional organization of the cortex of the postcentral gyrus of the monkey: a correlation of findings obtained in a single unit analysis with cytoarchitecture. , 1959, Bulletin of the Johns Hopkins Hospital.

[22]  E P Gardner,et al.  Spatial integration of multiple-point stimuli in primary somatosensory cortical receptive fields of alert monkeys. , 1980, Journal of Neurophysiology.

[23]  E P Gardner,et al.  Temporal integration of multiple-point stimuli in primary somatosensory cortical receptive fields of alert monkeys. , 1980, Journal of neurophysiology.

[24]  C. G. Phillips,et al.  Projection from low‐threshold muscle afferents of hand and forearm to area 3a of baboon's cortex , 1971, The Journal of physiology.

[25]  M. Kato,et al.  Subcortical, thalamic and cortical somatosensory evoked potentials to median nerve stimulation. , 1984, Electroencephalography and clinical neurophysiology.

[26]  V. Jousmäki,et al.  Somatosensory evoked fields to large-area vibrotactile stimuli , 1999, Clinical Neurophysiology.

[27]  J. Kaas,et al.  The somatotopic organization of area 2 in macaque monkeys , 1985, The Journal of comparative neurology.

[28]  J. Huttunen,et al.  Magnetic cortical responses evoked by tactile stimulation of the middle finger in man , 1986, Pflügers Archiv.

[29]  C C Wood,et al.  Electrical sources in human somatosensory cortex: identification by combined magnetic and potential recordings. , 1985, Science.

[30]  R Salmelin,et al.  Comparison of somatosensory evoked fields to airpuff and electric stimuli. , 1994, Electroencephalography and clinical neurophysiology.