title: EEG activities in the orbitofrontal cortex and dorsolateral prefrontal cortex during the development of morphine dependence, tolerance and withdrawal in rhesus monkeys.
abstract: Investigating the activities of the prefrontal cortex (PFC) in the process of addiction is valuable for understanding the neural mechanism underlying the impairments of the PFC after drug abuse. However, limited data are obtained from primate animals and few studies analyze Electroencephalogram (EEG) in the gamma band, which plays an important role in cognitive functions. In addition, it is yet unclear whether drug abuse affects the orbitofrontal cortex (OFC) and dorsolateral PFC (DLPFC)--the two most important subregions of the PFC--in similar ways or not. The aim of this study is to address these issues. We recorded EEG in the OFC and DLPFC in three rhesus monkeys. All animals received a course of saline (NaCl 0.9%, 2 ml) injection (5 days) followed by 10 days of morphine injection (every 12 h), and then a further series of saline injection (7 days). A main finding in the present study was that morphine decreased EEG power in all frequency bands in a short period after injection in both the OFC and DLPFC in monkeys. And gamma power decreased not just in a short period after morphine injection but lasted to 12 h after injection. Moreover, we found that although the changes in EEG activities in the OFC and DLPFC at 30-35 min after injection were similar, the DLPFC was more sensitive to the effect of morphine than the OFC.
authors.affiliation: Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, PR China.
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.forename: Yancheng
authors.initials: Y
authors.lastname: Liu
authors.forename: Yaodong
authors.initials: Y
authors.lastname: Fan
authors.forename: Hualin
authors.initials: H
authors.lastname: Yu
authors.forename: Fraser A W
authors.initials: FA
authors.lastname: Wilson
authors.forename: Yuanye
authors.initials: Y
authors.lastname: Ma
authors.forename: Xintian
authors.initials: X
authors.lastname: Hu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004361:Drug Tolerance / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology*; D008253:Macaca mulatta; D009020:Morphine / Q000008:administration & dosage; D009021:Morphine Dependence / Q000503:physiopathology*; D009294:Narcotics / Q000008:administration & dosage; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D009294:Narcotics; D009020:Morphine