title: Effects of general anesthesia on high-frequency oscillations in somatosensory evoked potentials.
abstract: To determine the characteristics of high-frequency oscillations (HFOs) of cortical somatosensory evoked potentials (SEPs), the effect of general anesthesia on HFOs and low-frequency primary cortical responses was studied. The authors recorded SEPs elicited by median nerve stimulation directly from human brains of seven patients who underwent implantation of subdural electrodes before surgical treatment of intractable epilepsy. Recordings were made before and during general anesthesia. Changes in the number of HFOs and amplitude ratios of HFOs/primary cortical responses were analyzed. Under general anesthesia, the number of HFO peaks and the amplitude ratios were significantly decreased. General anesthesia induced remarkably decreased HFO activities when compared to low-frequency SEPs, suggesting that each of those originated from different generators. Possible relations between gamma-amino-butyric acid (GABA)ergic inhibitory interneurons and HFOs are discussed.
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu City, Japan. k01197@nmcn.jp
authors.forename: Eiichirou
authors.initials: E
authors.lastname: Urasaki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Genmoto
authors.forename: Akira
authors.initials: A
authors.lastname: Yokota
authors.forename: Rieko
authors.initials: R
authors.lastname: Maeda
authors.forename: Naoki
authors.initials: N
authors.lastname: Akamatsu
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000768:Anesthesia, General / Q000379:methods*; D004558:Electric Stimulation / Q000379:methods; D004827:Epilepsy / Q000628:therapy; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006612:High-Frequency Ventilation; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000187:drug effects / Q000503:physiopathology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D013003:Somatosensory Cortex / Q000187:drug effects* / Q000502:physiology