Intrinsic functional architecture in the anaesthetized monkey brain

• Published in: Nature Vol. 447; no. 7140; pp. 83 - 86
• Main Authors: Fox, M. D, Baker, J. T, Van Essen, D. C, Snyder, L. H, Patel, G. H, Corbetta, M, Snyder, A. Z, Raichle, M. E, Vincent, J. L, Zempel, J. M
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 03.05.2007; Nature Publishing Group
• Subjects: Anatomy; Anesthesia; Anesthetics, Inhalation - pharmacology; Animals; Biological and medical sciences; Blood; Brain; Brain - anatomy & histology; Brain - drug effects; Brain - physiology; Brain Mapping; Central nervous system; Consciousness; Energy consumption; Fluctuations; Fundamental and applied biological sciences. Psychology; Humans; Isoflurane - pharmacology; Macaca fascicularis - anatomy & histology; Macaca fascicularis - physiology; Macaca mulatta - anatomy & histology; Macaca mulatta - physiology; Magnetic Resonance Imaging; Monkeys & apes; Neurosciences; NMR; Nuclear magnetic resonance; Physiological responses; Physiology; Vertebrates: nervous system and sense organs; Visual Cortex - anatomy & histology; Visual Cortex - drug effects; Visual Cortex - physiology; Human; Oxygen; Stimulus; Functional organization; Central nervous system; Monkey; Cognition; Distributed system; Nuclear magnetic resonance imaging; Encephalon; Visual system; Vertebrata; Mammalia; Primates; Functional imaging
• ISSN: 0028-0836; 1476-4687; 1476-4679
• DOI: 10.1038/nature05758

The traditional approach to studying brain function is to measure physiological responses to controlled sensory, motor and cognitive paradigms. However, most of the brain's energy consumption is devoted to ongoing metabolic activity not clearly associated with any particular stimulus or behaviour. Functional magnetic resonance imaging studies in humans aimed at understanding this ongoing activity have shown that spontaneous fluctuations of the blood-oxygen-level-dependent signal occur continuously in the resting state. In humans, these fluctuations are temporally coherent within widely distributed cortical systems that recapitulate the functional architecture of responses evoked by experimentally administered tasks. Here, we show that the same phenomenon is present in anaesthetized monkeys even at anaesthetic levels known to induce profound loss of consciousness. We specifically demonstrate coherent spontaneous fluctuations within three well known systems (oculomotor, somatomotor and visual) and the 'default' system, a set of brain regions thought by some to support uniquely human capabilities. Our results indicate that coherent system fluctuations probably reflect an evolutionarily conserved aspect of brain functional organization that transcends levels of consciousness.