title: Gradual emergence of spontaneous correlated brain activity during fading of general anesthesia in rats: Evidences from fMRI and local field potentials.
abstract: Intrinsic brain activity is characterized by the presence of highly structured networks of correlated fluctuations between different regions of the brain. Such networks encompass different functions, whose properties are known to be modulated by the ongoing global brain state and are altered in several neurobiological disorders. In the present study, we induced a deep state of anesthesia in rats by means of a ketamine/medetomidine peritoneal injection, and analyzed the time course of the correlation between the brain activity in different areas while anesthesia spontaneously decreased over time. We compared results separately obtained from fMRI and local field potentials (LFPs) under the same anesthesia protocol, finding that while most profound phases of anesthesia can be described by overall sparse connectivity, stereotypical activity and poor functional integration, during lighter states different frequency-specific functional networks emerge, endowing the gradual restoration of structured large-scale activity seen during rest. Noteworthy, our in vivo results show that those areas belonging to the same functional network (the default-mode) exhibited sustained correlated oscillations around 10Hz throughout the protocol, suggesting the presence of a specific functional backbone that is preserved even during deeper phases of anesthesia. Finally, the overall pattern of results obtained from both imaging and in vivo-recordings suggests that the progressive emergence from deep anesthesia is reflected by a corresponding gradual increase of organized correlated oscillations across the cortex.
authors: Center for Brain and Cognition, Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona 08018, Spain. Electronic address: ruggero.bettinardi@upf.edu.
authors: Ruggero G
authors: RG
authors: Bettinardi
authors: Institut D' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain.
authors: Núria
authors: N
authors: Tort-Colet
authors: Institut D' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain.
authors: Marcel
authors: M
authors: Ruiz-Mejias
authors: Institut D' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain.
authors: Maria V
authors: MV
authors: Sanchez-Vives
authors: Center for Brain and Cognition, Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona 08018, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain.
authors: Gustavo
authors: G
authors: Deco
mesh_terms: D018681:Anesthetics, General / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000502:physiology*; D001931:Brain Mapping; D058256:Brain Waves / Q000187:drug effects; D003344:Cortical Synchronization / Q000187:drug effects; D007649:Ketamine / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D008297:Male; D020926:Medetomidine / Q000494:pharmacology; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018681:Anesthetics, General; D007649:Ketamine; D020926:Medetomidine
keywords: Alpha rhythm; Anesthesia levels; Brain states; Connectivity; Default-mode network; Gamma rhythm