The effects of stimulus rates on high frequency oscillations of median nerve somatosensory-evoked potentials--direct recording study from the human cerebral cortex.

Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, Iseigaoka 1-1, Yahata Nishi-ku, Kitakyushu City 807-8555, Japan.
Clinical Neurophysiology (Impact Factor: 2.98). 12/2002; 113(11):1794-7. DOI: 10.1016/S1388-2457(02)00291-2
Source: PubMed

ABSTRACT To study the effects of different stimulus rates on high-frequency oscillations (HFOs) of somatosensory-evoked potentials (SEPs), we recorded median nerve SEPs directly from the human cerebral cortex.
SEPs were recorded from subdural electrodes in 5 patients with intractable epilepsy, under the conditions of low (3.3Hz) and high (12.3Hz) stimulus rates.
Increased stimulus rates to the median nerve from 3.3 to 12.3Hz showed a pronounced amplitude reduction of HFOs when compared with the primary N20-P20, area 3b, and P25, area 1, responses.
HFOs were more sensitive to a high stimulus rate than the primary cortical responses, suggesting that the post-synaptic intracortical activities may greatly contribute to the HFO generation.

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