Influence of anesthesia on cerebral blood flow, cerebral metabolic rate, and brain functional connectivity

Bonhomme, Vincent; Hans, Pol; Brichant, Jean François; Vanhaudenhuyse, Audrey; Boly, Mélanie; Laureys, Steven

doi:10.1097/aco.0b013e32834a12a1

Cited by 51 publications

(39 citation statements)

References 49 publications

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“…Previous studies demonstrated diverse effects of anesthesia on resting-state brain connectivity Bonhomme et al, 2011Bonhomme et al, , 2012Hudetz, 2012;Nallasamy and Tsao, 2011). The early work of Kiviniemi and associates (2005) indicated that sedative levels of the intravenous anesthetic, midazolam enhanced the amplitude and synchrony of spontaneous BOLD signal fluctuations.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, a rapidly expanding group of investigators began to approach the problem by applying anesthetic agents to reversibly modulate the state of consciousness in search of unique neuronal correlates of state transitions in the brain in both humans and animals Boly et al, 2013;Bonhomme et al, 2012;Brown et al, 2010;Hudetz, 2012;Mashour and Alkire, 2013). Tentative findings have suggested a role for large-scale thalamocortical and corticocortical networks, subcortical modulatory and higher cortical integration centers in the orchestration of the reversible transitions between conscious and unconscious states (Alkire, 2008;Bonhomme et al, 2011;Boveroux et al, 2010;Ferrarelli et al, 2010;Guldenmund et al, 2013;Hudetz, 2012;Langsjo et al, 2012;Lee et al, 2009aLee et al, , 2009bLee et al, , 2013Mhuircheartaigh et al, 2010;Nallasamy and Tsao, 2011;Peltier et al, 2005;Schrouff et al, 2011;White and Alkire, 2003). However, a final common pathway or unitary theory for losing and regaining consciousness has not emerged.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Repertoire of Intrinsic Brain States Is Reduced in Propofol-Induced Unconsciousness

2015

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The richness of conscious experience is thought to scale with the size of the repertoire of causal brain states, and it may be diminished in anesthesia. We estimated the state repertoire from dynamic analysis of intrinsic functional brain networks in conscious sedated and unconscious anesthetized rats. Functional resonance images were obtained from 30-min whole-brain resting-state blood oxygen level-dependent (BOLD) signals at propofol infusion rates of 20 and 40 mg/kg/h, intravenously. Dynamic brain networks were defined at the voxel level by sliding window analysis of regional homogeneity (ReHo) or coincident threshold crossings (CTC) of the BOLD signal acquired in nine sagittal slices. The state repertoire was characterized by the temporal variance of the number of voxels with significant ReHo or positive CTC. From low to high propofol dose, the temporal variances of ReHo and CTC were reduced by 78% -20% and 76% -20%, respectively. Both baseline and propofol-induced reduction of CTC temporal variance increased from lateral to medial position. Group analysis showed a 20% reduction in the number of unique states at the higher propofol dose. Analysis of temporal variance in 12 anatomically defined regions of interest predicted that the largest changes occurred in visual cortex, parietal cortex, and caudate-putamen. The results suggest that the repertoire of large-scale brain states derived from the spatiotemporal dynamics of intrinsic networks is substantially reduced at an anesthetic dose associated with loss of consciousness.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic Repertoire of Intrinsic Brain States Is Reduced in Propofol-Induced Unconsciousness

2015

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“…However, studies have shown that anesthesia has a significantly weaker influence in early sensory cortical areas and very likely in the downstream spinal cord than higher order cognitive brain regions (for a review, see ref. 34). We believe that anesthesia is unlikely a major influence on the horn-to-horn connectivity differences between anesthetized monkeys and awake humans (4,5) or before and after injury.…”

Section: Discussion Widespread Fmri Responses To Noxious Stimuli Withmentioning

confidence: 99%

Injury alters intrinsic functional connectivity within the primate spinal cord

Chen

Mishra²,

Yang³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Recent demonstrations of correlated low-frequency MRI signal variations between subregions of the spinal cord at rest in humans, similar to those found in the brain, suggest that such resting-state functional connectivity constitutes a common feature of the intrinsic organization of the entire central nervous system. We report our detection of functional connectivity within the spinal cords of anesthetized squirrel monkeys at rest and show that the strength of connectivity within these networks is altered by the effects of injuries. By quantifying the low-frequency MRI signal correlations between different horns within spinal cord gray matter, we found distinct functional connectivity relationships between the different sensory and motor horns, a pattern that was similar to activation patterns evoked by nociceptive heat or tactile stimulation of digits. All horns within a single spinal segment were functionally connected, with the strongest connectivity occurring between ipsilateral dorsal and ventral horns. Each horn was strongly connected to the same horn on neighboring segments, but this connectivity reduced drastically along the spinal cord. Unilateral injury to the spinal cord significantly weakened the strength of the intrasegment horn-to-horn connectivity only on the injury side and in slices below the lesion. These findings suggest resting-state functional connectivity may be a useful biomarker of functional integrity in injured and recovering spinal cords.hand | spinal cord injury | resting state fMRI | monkey | cervical spinal cord R esting-state functional connectivity (rsFC) has been widely used to identify and characterize neural circuits in the brain (1-3), and its presentation at various spatial scales and its changes with specific physiological conditions confirm its fundamental role in maintaining normal brain function (4, 5). More importantly, alterations of rsFC networks in various disease conditions have altered our view about the functional significance of spontaneous baseline neural activity (3). Two very recent reports of success in detecting intrinsic functional circuits in human spines using resting-state fMRI once more suggest that rsFC is a fundamental, common feature of the entire nervous system (6, 7).Despite these exciting findings in human subjects, the functional and behavioral relevance of the intrinsic functional networks within the spine gray matter remains largely obscure, and there have been no previous reports attempting to understand their significance. One way to address this question is to manipulate the network and then examine how the network reacts to the manipulation. This type of approach is impossible to execute in humans but can be performed in nonhuman primates in a very well-controlled manner. Thus, this study aimed to better understand the functional and behavioral relevance of newly identified rsFC in the spinal cord by first determining whether similar intrinsic rsFC networks can be detected in the spinal cords of anesthetized monkeys. We also sought to determ...

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“…15 Among companion dogs, most Chihuahuas have a molera of the head, and the lacuna may remain open throughout life. Therefore, we realized that a Chihuahua molera is a boneless locus and, consequently, NIRS beams easily reach the cerebral cortex by passing through the molera in the scalp, and is, therefore, ideal for a pilot study of canine brain NIRS in conscious state.…”

Section: Introductionmentioning

confidence: 99%

Examiner’s finger-mounted near-infrared spectroscopy is feasible to analyze cerebral and skeletal muscle oxygenation in conscious Chihuahuas

Hiwatashi

Doi²,

Mizuno

et al. 2017

J. Biomed. Opt

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, "Examiner's finger-mounted nearinfrared spectroscopy is feasible to analyze cerebral and skeletal muscle oxygenation in conscious Chihuahuas," J. Biomed. Opt. 22(2), 026006 (2017), doi: 10.1117/1.JBO.22.2.026006. Abstract. To measure regional saturation of oxygen (rSO 2 ) of hemoglobin and total hemoglobin index (HbI) in the brain (through the molera of the head) and skeletal muscle (musculus gracilis) of conscious Chihuahua dogs using an examiner's finger-mounted near-infrared spectroscopy (NIRS) device, Toccare, we investigated brain and skeletal muscle NIRS in 48 Chihuahuas without severe disease. To measure rSO 2 and total HbI, a Toccare probe was placed on the molera of the head and musculus gracilis of each dog for real-time recording. Stable NIRS values were obtained within 10 s. We also examined the effect of anesthesia on rSO 2 and total HbI of a Chihuahua. Cerebral rSO 2 values (59% AE 7%) were significantly lower than those obtained at femoral regions (67% AE 6%), whereas total HbI values in the brain (0.38 AE 0.09) were significantly higher than those of the musculus gracilis (0.20 AE 0.05). Sedation with a combination of medetomidine and ketamine decreased cerebral rSO 2 along with a corresponding reduction in heart rate. Sevoflurane anesthesia with 100% O 2 maintained rSO 2 in the brain with an even lower heart rate. In conclusions, we measured brain and skeletal muscle rSO 2 of hemoglobin in conscious Chihuahuas using a newly developed NIRS device, Toccare, and found that changes in cerebral oxygenation levels were associated with administration of anesthetics. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Influence of anesthesia on cerebral blood flow, cerebral metabolic rate, and brain functional connectivity

Abstract: Accumulating evidence suggests that hypnotic anesthetic agents disrupt large-scale cerebral connectivity. This would result in an inability of the brain to generate and integrate information, while external sensory information is still processed at a lower order of complexity.

Cited by 51 publications

References 49 publications

Dynamic Repertoire of Intrinsic Brain States Is Reduced in Propofol-Induced Unconsciousness

Dynamic Repertoire of Intrinsic Brain States Is Reduced in Propofol-Induced Unconsciousness

Injury alters intrinsic functional connectivity within the primate spinal cord

Examiner’s finger-mounted near-infrared spectroscopy is feasible to analyze cerebral and skeletal muscle oxygenation in conscious Chihuahuas

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