Intrinsic functional architecture in the anaesthetized monkey brain

Abstract

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.

MR connectomics: Principles and challenges

“…We note that, although the relationship between indirect SC and rsFC is weaker than the relationship between direct SC and rsFC, it is nonetheless highly significant. Consistent with the observation of Vincent et al (2007), that interhemispheric rsFC between the visual cortices is most likely subserved by polysynaptic connections, we find in our data that indirect cortico-cortical SC is an especially strong predictor of .…”

“…On the other hand resting-state fMRI has gained in acceptance over the last years for the mapping of functional networks (Raichle et al, 2001;Vincent et al, 2007) that must to some extent be related to the underlying structural connectivity. It has the double advantage of being completely unrelated to diffusion imaging and of being measured in the same scan session and in the same subject.…”

Mesoscale infraslow spontaneous membrane potential fluctuations recapitulate high-frequency activity cortical motifs

“…This is of critical importance in the analysis of infraslow activity given its, by definition, very slow nature and the consequently long-duration observation times necessary to assess it. Furthermore, descriptions of resting-state infraslow activity in humans, non-human primates and rodents have demonstrated these networks to be robust and persistent in task-negative awake states in addition to states of natural sleep and anaesthesia 5,9,32 . Furthermore, our previous data indicated that connectivity maps from quiet awake and anaesthetized states are similar 27,33 .…”

“…From its early description as 'infraslow' 4 , spontaneous or resting-state activity at this very low-frequency domain (o0.1 Hz) has been observed as a consistent feature of ongoing brain activity across different species [4][5][6][7] and across different brain states 5,[8][9][10] , though its precise function and mechanistic underpinnings remain unclear. In the developing brain, electrophysiological infraslow activity in the form of neuronal activity transients or bursting activity has been linked with the development of neuronal networks 11,12 , whereas in the adult brain, infraslow activity has been demonstrated to synchronize with higher-frequency brain activity 13,14 and to correlate to variability in behavioural performance 15,16 .…”

Correlation between resting state fMRI total neuronal activity and PET metabolism in healthy controls and patients with disorders of consciousness

“…2006; Fox and Raichle 2007; Vincent et al. 2007). These results suggest that the study of higher order associative network functionality using resting state fMRI is useful in the absence of patients’ collaboration (Greicius et al.…”