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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Urasaki
Eiichirou
E
Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, Iseigaoka 1-1, Yahata Nishi-ku, Kitakyushu City 807-8555, Japan. urasaki@med.uoeh-u.ac.jp
Genmoto
Tetsuya
T
Akamatsu
Naoki
N
Wada
Shin-ichi
S
Yokota
Akira
A
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*