title: Altered temporal variance and neural synchronization of spontaneous brain activity in anesthesia.
abstract: Recent studies at the cellular and regional levels have pointed out the multifaceted importance of neural synchronization and temporal variance of neural activity. For example, neural synchronization and temporal variance has been shown by us to be altered in patients in the vegetative state (VS). This finding nonetheless leaves open the question of whether these abnormalities are specific to VS or rather more generally related to the absence of consciousness. The aim of our study was to investigate the changes of inter- and intra-regional neural synchronization and temporal variance of resting state activity in anesthetic-induced unconsciousness state. Applying an intra-subject design, we compared resting state activity in functional magnetic resonance imaging (fMRI) between awake versus anesthetized states in the same subjects. Replicating previous studies, we observed reduced functional connectivity within the default mode network (DMN) and thalamocortical network in the anesthetized state. Importantly, intra-regional synchronization as measured by regional homogeneity (ReHo) and temporal variance as measured by standard deviation (SD) of the BOLD signal were significantly reduced in especially the cortical midline regions, while increased in the lateral cortical areas in the anesthetized state. We further found significant frequency-dependent effects of SD in the thalamus, which showed abnormally high SD in Slow-5 (0.01-0.027 Hz) in the anesthetized state. Our results show for the first time of altered temporal variance of resting state activity in anesthesia. Combined with our findings in the vegetative state, these findings suggest a close relationship between temporal variance, neural synchronization and consciousness.
authors.affiliation: Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, People's Republic of China; Institute of Mental Health Research, University of Ottawa, Ottawa, Canada.
authors.forename: Zirui
authors.initials: Z
authors.lastname: Huang
authors.forename: Zhiyao
authors.initials: Z
authors.lastname: Wang
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Dai
authors.forename: Jinsong
authors.initials: J
authors.lastname: Wu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Weimin
authors.initials: W
authors.lastname: Liang
authors.forename: Ying
authors.initials: Y
authors.lastname: Mao
authors.forename: Zhong
authors.initials: Z
authors.lastname: Yang
authors.forename: Giles
authors.initials: G
authors.lastname: Holland
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Georg
authors.initials: G
authors.lastname: Northoff
mesh_terms: D000328:Adult; D000758:Anesthesia; D000777:Anesthetics / Q000008:administration & dosage*; D001921:Brain / Q000098:blood supply* / Q000187:drug effects*; D001931:Brain Mapping; D004333:Drug Administration Routes; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage*; D008875:Middle Aged; D008959:Models, Neurological; D010100:Oxygen / Q000097:blood; D015742:Propofol / Q000008:administration & dosage*; D000077149:Sevoflurane; D014851:Wakefulness
chemical_list: D000777:Anesthetics; D008738:Methyl Ethers; D000077149:Sevoflurane; D010100:Oxygen; D015742:Propofol
keywords: anesthesia; consciousness; cortical midline regions; fMRI; functional connectivity; low-frequency fluctuations; resting state