SOMATOSENSORY SYSTEMS, PAINDissociated behavior of low-frequency responses and high-frequency oscillations after systemic morphine administration in conscious ratsLi, Guo-Lianga; Qiao, Zhi-Meib c; Han, Ji-Shengc; Luo, Feic dAuthor Information aDepartment of Anesthesiology, Fourth Affiliated Hospital of Hebei Medical University, Shijiazhuang bDepartment of Biomedical Engineering, School of Medicine, Tsinghua University cNeuroscience Research Institute and Department of Neurobiology, Peking University dKey Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China Correspondence to Dr Fei Luo, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 10A Datun Road, Chaoyang District, Beijing 100101, China Tel: +86 10 64844991; fax: +86 10 64844991; e-mail: firstname.lastname@example.org Guo-Liang Li and Zhi-Mei Qiao contributed equally to this study Received 7 March 2009 accepted 7 May 2009 NeuroReport: January 6th, 2010 - Volume 21 - Issue 1 - p 2-7 doi: 10.1097/WNR.0b013e32832e0c5a Buy SDC Metrics Abstract It has been proposed that high-frequency oscillations (HFOs) and underlying conventional somatosensory-evoked potentials (SEPs) have different brain origins. To further explore the neural mechanism of HFOs, we recorded the SEPs responding to high-intensity electrical stimulation applied to the hind paw of conscious, freely moving rats. We also investigated the effect of systemic morphine on HFOs and the conventional SEPs. HFOs after high-intensity electrical stimulation showed a widespread distribution in frontal and temporal regions of the brain. The amplitude of HFOs was significantly decreased by systemic morphine, whereas the primary conventional SEP components remained unaffected. The different changes in HFOs and primary SEP components after systemic morphine administration provided further evidence for the hypothesis that HFOs and underlying conventional SEP components have different origins. © 2010 Lippincott Williams & Wilkins, Inc.