Steady-state vibration somatosensory evoked potentials: physiological characteristics and tuning function

OBJECTIVE The steady-state somatosensory evoked potentials (S-SEPs) to vibratory stimulation were recorded to characterize their physiological properties. METHODS Vibratory stimuli were applied to the right palmar surface in 10 normal subjects. A total of 200 responses were recorded from electrodes at 2 cm posterior to C3, Cz and C4 and 2 cm anterior to C3. All responses were Fourier analyzed and the amplitudes of the first (1F) and second (2F) harmonic components were thus obtained. The effects of modulation frequency (5-30 Hz) and stimulus intensity (0.001-0.1 Newton (N)) on S-SEPs were studied. RESULTS The amplitudes of 1F and 2F were greatest at the electrode 2 cm posterior to C3, 1F being predominant. The mean 1F amplitudes as a function of modulation frequency showed a bimodal distribution with a trough at 14 Hz and a peak at 21 Hz. The mean 1F amplitudes showed a linear increase of up to 0.05 N and thereafter reached a plateau against the logarithmic stimulus intensity axis. CONCLUSION Vibratory S-SEPs may originate from the primary somatosensory cortex and provide information on the fast-adapting mechanoreceptive afferents. The temporal resonance at 21 Hz places the somatosensory system between the visual and auditory systems.

[1]  V. Mountcastle,et al.  The sense of flutter-vibration: comparison of the human capacity with response patterns of mechanoreceptive afferents from the monkey hand. , 1968, Journal of neurophysiology.

[2]  S Makeig,et al.  Auditory steady-state responses: threshold prediction using phase coherence. , 1987, Electroencephalography and clinical neurophysiology.

[3]  T Imada,et al.  Human somatosensory evoked magnetic fields to vibratory stimulation of the index finger: is there frequency organization in SI? , 1998, Electroencephalography and clinical neurophysiology.

[4]  M. Onofrj,et al.  Maps of somatosensory evoked potentials (SEPs) to mechanical (tapping) stimuli: comparison with P14, N20, P22, N30 of electrically elicited SEPs. , 1990, Electroencephalography and clinical neurophysiology.

[5]  V. Mountcastle,et al.  Capacities of humans and monkeys to discriminate vibratory stimuli of different frequency and amplitude: a correlation between neural events and psychological measurements. , 1975, Journal of neurophysiology.

[6]  R J Sclabassi,et al.  Somatosensory responses to stimulus trains: normative data. , 1974, Electroencephalography and clinical neurophysiology.

[7]  D. Regan.  Human brain electrophysiology: Evoked potentials and evoked magnetic fields in science and medicine , 1989 .

[8]  J. Hyvärinen,et al.  Cortical neuronal mechanisms in flutter-vibration studied in unanesthetized monkeys. Neuronal periodicity and frequency discrimination. , 1969, Journal of neurophysiology.

[9]  T W Picton,et al.  Reliability estimates for steady-state evoked potentials. , 1987, Electroencephalography and clinical neurophysiology.

[10]  S. Tobimatsu,et al.  Normal variability of the amplitude and phase of steady-state VEPs. , 1996, Electroencephalography and clinical neurophysiology.

[11]  H Pratt,et al.  Mechanically and electrically evoked somatosensory potentials in humans: effects of stimulus presentation rate. , 1980, Electroencephalography and clinical neurophysiology.

[12]  A. Starr,et al.  Mechanically and electrically evoked somatosensory potentials in normal humans , 1979, Neurology.

[13]  M. Trulsson,et al.  Periodic microstimulation of single mechanoreceptive afferents produces frequency-following responses in human EEG. , 1997, Journal of neurophysiology.

[14]  S Tobimatsu,et al.  The effect of binocular stimulation on each component of transient and steady-state VEPs. , 1996, Electroencephalography and clinical neurophysiology.

[15]  R. Johansson,et al.  Responses of mechanoreceptive afferent units in the glabrous skin of the human hand to sinusoidal skin displacements , 1982, Brain Research.

[16]  Robert Galambos,et al.  TACTILE AND AUDITORY STIMULI REPEATED AT HIGH RATES (30–50 PER SEC) PRODUCE SIMILAR EVENT RELATED POTENTIALS * , 1980 .

[17]  D. Regan,et al.  COMPARISON OF TRANSIENT AND STEADY‐STATE METHODS * , 1980, Annals of the New York Academy of Sciences.

[18]  A Z Snyder,et al.  Steady-state vibration evoked potentials: descriptions of technique and characterization of responses. , 1992, Electroencephalography and clinical neurophysiology.

[19]  H Hämäläinen,et al.  Human somatosensory evoked potentials to mechanical pulses and vibration: contributions of SI and SII somatosensory cortices to P50 and P100 components. , 1990, Electroencephalography and clinical neurophysiology.