We examined the differences in interhemispheric functional correlation in the somatosensory system using coherence (Coh) analysis. Ten healthy adult volunteers served as subjects for this experiment. Vibratory stimulation (modulation frequency, 21 Hz) was given to each palm to record vibratory steady-state somatosensory evoked potentials (S-SEPs). S-SEPs were recorded from four electrodes placed at 2 cm posterior and anterior to C3 and C4, referred to an electrode at Fpz, respectively. For comparison, unstimulated S-SEPs were also recorded. A total of 50 responses of 1-s epochs was averaged and subjected to discrete fast Fourier transforms to yield the amplitudes of major harmonic components and Coh value. The Coh value between the two signals, x and y at each frequency f, was calculated as [Cohxy(f)]2=[Sxy(f)]2/[S xx(f)×Syy(f)]. The amplitude at 21 Hz in the contralateral somatosensory area was significantly larger than that in the other electrodes. The interhemispheric Coh of the somatosensory area at 21 Hz was significantly lower than that in the unstimulated condition or intrahemispheric Coh. The initial somatosensory information is desynchronized. These findings indicate less significance of interhemispheric correlation as the first step of the vibratory information processing in the somatosensory cortex.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Clinical Neurology
- Developmental Biology