Publications by authors named "Vincent Bonhomme"

53 Publications

A morphometric approach to track opium poppy domestication.

Sci Rep 2021 May 7;11(1):9778. Epub 2021 May 7.

ISEM, University of Montpellier, CNRS-IRD-EPHE, Montpellier, France.

Opium poppy (Papaver somniferum L. subsp. somniferum) was likely domesticated in the Western Mediterranean, where its putative wild ancestor is indigenous, and then spread to central and northern Europe. While opium poppy seeds are regularly identified in archaeobotanical studies, the absence of morphological criteria to distinguish the seeds of wild and domestic forms prevents the documentation of their respective historical and geographical occurrences and of the process of opium domestication as a whole. To fill this gap and better understand the status of this crop in the Neolithic, we combined seed outline analyses, namely elliptic Fourier transforms, with other morphometric descriptors to describe and identify Papaver setigerum, Papaver somniferum and other Papaver taxa. The combination of all measured parameters gives the most precise predictions for the identification of all seven taxa. We finally provide a case study on a Neolithic assemblage from a pile-dwelling site in Switzerland (Zurich-Parkhaus Opéra, ca. 3170 BC). Our results indicate the presence of mixed populations of domestic and wild seeds belonging to the P. somniferum group, suggesting that the plant was already in the process of domestication at the end of 4th millennium BC. Altogether, these results pave the way to understand the geography and history of the poppy domestication and its spread into Europe.
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http://dx.doi.org/10.1038/s41598-021-88964-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8105347PMC
May 2021

How hot is the hot zone? Computational modelling clarifies the role of parietal and frontoparietal connectivity during anaesthetic-induced loss of consciousness.

Neuroimage 2021 05 9;231:117841. Epub 2021 Feb 9.

School of Computing, University of Kent, United Kingdom; Department of Clinical Neurosciences, University of Cambridge, United Kingdom.

In recent years, specific cortical networks have been proposed to be crucial for sustaining consciousness, including the posterior hot zone and frontoparietal resting state networks (RSN). Here, we computationally evaluate the relative contributions of three RSNs - the default mode network (DMN), the salience network (SAL), and the central executive network (CEN) - to consciousness and its loss during propofol anaesthesia. Specifically, we use dynamic causal modelling (DCM) of 10 min of high-density EEG recordings (N = 10, 4 males) obtained during behavioural responsiveness, unconsciousness and post-anaesthetic recovery to characterise differences in effective connectivity within frontal areas, the posterior 'hot zone', frontoparietal connections, and between-RSN connections. We estimate - for the first time - a large DCM model (LAR) of resting EEG, combining the three RSNs into a rich club of interconnectivity. Consistent with the hot zone theory, our findings demonstrate reductions in inter-RSN connectivity in the parietal cortex. Within the DMN itself, the strongest reductions are in feed-forward frontoparietal and parietal connections at the precuneus node. Within the SAL and CEN, loss of consciousness generates small increases in bidirectional connectivity. Using novel DCM leave-one-out cross-validation, we show that the most consistent out-of-sample predictions of the state of consciousness come from a key set of frontoparietal connections. This finding also generalises to unseen data collected during post-anaesthetic recovery. Our findings provide new, computational evidence for the importance of the posterior hot zone in explaining the loss of consciousness, highlighting also the distinct role of frontoparietal connectivity in underpinning conscious responsiveness, and consequently, suggest a dissociation between the mechanisms most prominently associated with explaining the contrast between conscious awareness and unconsciousness, and those maintaining consciousness.
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http://dx.doi.org/10.1016/j.neuroimage.2021.117841DOI Listing
May 2021

Seed morphology uncovers 1500 years of vine agrobiodiversity before the advent of the Champagne wine.

Sci Rep 2021 Jan 27;11(1):2305. Epub 2021 Jan 27.

ISEM, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France.

A crucial aspect of viticulture is finally unveiled as the historical dynamics of its agrobiodiversity are described in the Champagne region for the first time. Outline analyses were carried out to compare the morphology of archaeological grape seeds from Troyes and Reims (first c. AD to fifteenth c. AD) with that of a reference collection of modern seeds, including wild vines and traditional grape varieties, believed to be ancient and characteristic of the French vine heritage. This allows us to document the chronological dynamics of the use of the wild Vitis type and of the diversity of the varieties used, based on morphological disparity. After showing the existence of morphological types corresponding to geographical groups, we highlight a geochronological dynamic. Our results show that the wild type is used throughout the series, up to the Middle Ages. In addition, domestic forms, morphologically related to southern varietal groups, are very early involved in the Champagne grape agrodiversity. The groups corresponding to the typical grape varieties of today do not appear until the second millennium. These previously unsuspected dynamics are discussed in light of the social, societal and climatic changes documented for the period.
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http://dx.doi.org/10.1038/s41598-021-81787-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7840976PMC
January 2021

Optimizing digitalization effort in morphometrics.

Biol Methods Protoc 2020 16;5(1):bpaa023. Epub 2020 Nov 16.

Institut des Sciences de l'Evolution-Montpellier, UMR 5554-ISEM, CNRS, Université de Montpellier, IRD, EPHE, 2 place Eugène Bataillon, CC065, 34095 Montpellier Cedex 5, France.

Quantifying phenotypes is a common practice for addressing questions regarding morphological variation. The time dedicated to data acquisition can vary greatly depending on methods and on the required quantity of information. Optimizing digitization effort can be done either by pooling datasets among users, by automatizing data collection, or by reducing the number of measurements. Pooling datasets among users is not without risk since potential errors arising from multiple operators in data acquisition prevent combining morphometric datasets. We present an analytical workflow to estimate within and among operator biases and to assess whether morphometric datasets can be pooled. We show that pooling and sharing data requires careful examination of the errors occurring during data acquisition, that the choice of morphometric approach influences amount of error, and that in some cases pooling data should be avoided. The demonstration is based on a worked example ( teeth) using a combinations of 18 morphometric approaches and datasets for which we identified and quantified several potential sources of errors in the workflow. We show that it is possible to estimate the analytical power of a study using a small subset of data to select the best morphometric protocol and to optimize the number of variables necessary for analysis. In particular, we focus on semi-landmarks, which often produce an inflation of variables in contrast to the number of available observations use in statistical testing. We show how the workflow can be used for optimizing digitization efforts and provide recommendations for best practices in error management.
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http://dx.doi.org/10.1093/biomethods/bpaa023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7723759PMC
November 2020

Eco-evo-devo implications and archaeobiological perspectives of trait covariance in fruits of wild and domesticated grapevines.

PLoS One 2020 6;15(11):e0239863. Epub 2020 Nov 6.

ISEM, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France.

The phenotypic changes that occurred during the domestication and diversification of grapevine are well known, particularly changes in seed morphology, but the functional causes and consequences behind these variations are poorly understood. Wild and domesticate grapes differ, among others, in the form of their pips: wild grapes produce roundish pips with short stalks and cultivated varieties have more elongated pips with longer stalks. Such variations of form are of first importance for archaeobotany since the pip form is, most often, the only remaining information in archaeological settings. This study aims to enlighten archaeobotanical record and grapevine pip development by better understanding how size and shape (co)variates between pip and berry in both wild and domesticated Vitis vinifera. The covariation of berry size, number of seeds per berry ("piposity"), pip size and pip shape were explored on 49 grapevine accessions sampled among Euro-Mediterranean traditional cultivars and wild grapevines. We show that for wild grapevine, the higher the piposity, the bigger the berry and the more elongated the pip. For both wild and domesticated grapevine, the longer is the pip, the more it has a "domesticated" shape. Consequences for archaeobotanical studies are tested and discussed, and these covariations allowed the inference of berry dimensions from archaeological pips from a Southern France Roman site. This systematic exploration sheds light on new aspects of pip-berry relationship, in both size and shape, on grapevine eco-evo-devo changes during domestication, and invites to explore further the functional ecology of grapevine pip and berry and notably the impact of cultivation practices and human selection on grapevine morphology.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239863PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7647109PMC
January 2021

Influence of Levobupivacaine Regional Scalp Block on Hemodynamic Stability, Intra- and Postoperative Opioid Consumption in Supratentorial Craniotomies: A Randomized Controlled Trial.

Anesth Analg 2021 02;132(2):500-511

From the Department of Anesthesia and Intensive Care Medicine, Liege University Hospital, Liege, Belgium.

Background: The anesthetic management of supratentorial craniotomy (CR) necessitates tight intraoperative hemodynamic control. This type of surgery may also be associated with substantial postoperative pain. We aimed at evaluating the influence of regional scalp block (SB) on hemodynamic stability during the noxious events of supratentorial craniotomies and total intravenous anesthesia, its influence on intraoperative anesthetic agents' consumption, and its effect on postoperative pain control.

Methods: Sixty patients scheduled for elective CR were prospectively enrolled. Patient, anesthesiologist, and neurosurgeon were blind to the random performance of SB with either levobupivacaine 0.33% (intervention group [group SB], n = 30) or the same volume of saline (control group [group CO], placebo group, n = 30). General anesthesia was induced and maintained using target-controlled infusions of remifentanil and propofol that were adjusted according to hemodynamic parameters and state entropy of the electroencephalogram (SE), respectively. Mean arterial blood pressure (MAP), heart rate (HR), SE, and propofol and remifentanil effect-site concentrations (Ce) were recorded at the time of scalp block performance (Baseline), and 0, 1, 3, and 5 minutes after skull-pin fixation (SP), skin incision (SI), CR, and dura-mater incision (DM). Morphine consumption and postoperative pain intensity (0-10 visual analog scale [VAS]) were recorded 1, 3, 6, 24, and 48 hours after surgery. Propofol and remifentanil overall infusion rates were also recorded. Data were analyzed using 2-tailed Student unpaired t tests, 2-way mixed-design analysis of variance (ANOVA), and Tukey's honestly significant difference (HSD) tests for post hoc comparisons as appropriate.

Results: Demographics and length of anesthetic procedure of group CO and SB were comparable. SP, SI, and CR were associated with a significantly higher MAP in group CO than in group SB, at least at one of the time points of recording surrounding those noxious events. This was not the case at DM. Similarly, HR was significantly higher in group CO than in group SB during SP and SI, at least at 1 of the points of recording, but not during CR and DM. Propofol and remifentanil Ce and overall infusion rates were significantly higher in group CO than in group SB, except for propofol Ce during SP. Postoperative pain VAS and cumulative morphine consumption were significantly higher in group CO than in group SB.

Conclusions: In supratentorial craniotomies, SB improves hemodynamic control during noxious events and provides adequate and prolonged postoperative pain control as compared to placebo.
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http://dx.doi.org/10.1213/ANE.0000000000005230DOI Listing
February 2021

Generalized Prediction of Unconsciousness during Propofol Anesthesia using 3D Convolutional Neural Networks.

Annu Int Conf IEEE Eng Med Biol Soc 2020 07;2020:134-137

Neuroscience has generated a number of recent advances in the search for the neural correlates of consciousness, but these have yet to find valuable real-world applications. Electroencephalography under anesthesia provides a powerful experimental setup to identify electrophysiological signatures of altered states of consciousness, as well as a testbed for developing systems for automatic diagnosis and prognosis of awareness in clinical settings. In this work, we use deep convolutional neural networks to automatically differentiate sub-anesthetic states and depths of anesthesia, solely from one second of raw EEG signal. Our results with leave-one-participant-out-cross-validation show that behavioral measures, such as the Ramsay score, can be used to learn generalizable neural networks that reliably predict levels of unconsciousness in unseen transitional anesthetic states, as well as in unseen experimental setups and behaviors. Our findings highlight the potential of deep learning to detect progressive changes in anesthetic-induced unconsciousness with higher granularity than behavioral or pharmacological markers. This work has broader significance for identifying generalized patterns of brain activity that index states of consciousness.Clinical Relevance- In the United States alone, over 100,000 people receive general anesthesia every day, from which up to 1% is affected by unintended intraoperative awareness [1]. Despite this, brain-based monitoring of consciousness is not common in the clinic, and has had mixed success [2]. Given this context, our aim is to develop and explore an automated deep learning model that accurately predicts and interprets the depth and quality of anesthesia from the raw EEG signal.
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http://dx.doi.org/10.1109/EMBC44109.2020.9175324DOI Listing
July 2020

Potential adaptive divergence between subspecies and populations of snapdragon plants inferred from Q -F comparisons.

Mol Ecol 2020 08 24;29(16):3010-3021. Epub 2020 Jul 24.

PSL Université Paris, EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan Cedex, France.

Phenotypic divergence among natural populations can be explained by natural selection or by neutral processes such as drift. Many examples in the literature compare putatively neutral (F ) and quantitative genetic (Q ) differentiation in multiple populations to assess their evolutionary signature and identify candidate traits involved with local adaptation. Investigating these signatures in closely related or recently diversified species has the potential to shed light on the divergence processes acting at the interspecific level. Here, we conducted this comparison in two subspecies of snapdragon plants (eight populations of Antirrhinum majus pseudomajus and five populations of A. m. striatum) in a common garden experiment. We also tested whether altitude was involved with population phenotypic divergence. Our results identified candidate phenological and morphological traits involved with local adaptation. Most of these traits were identified in one subspecies but not the other. Phenotypic divergence increased with altitude for a few biomass-related traits, but only in A. m. striatum. These traits therefore potentially reflect A. m. striatum adaptation to altitude. Our findings imply that adaptive processes potentially differ at the scale of A. majus subspecies.
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http://dx.doi.org/10.1111/mec.15546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7540467PMC
August 2020

Long-Term Multicolumn-Lead Spinal Cord Stimulation Efficacy in Patients with Failed Back Surgery Syndrome: A Six-Year Prospective Follow-up Study.

World Neurosurg 2020 10 27;142:e245-e252. Epub 2020 Jun 27.

Department of Algology, Regional Hospital Center Citadelle, Liege, Belgium; University Department of Anesthesia and Intensive Care Medicine, Regional Hospital Center Citadelle, Liege, Belgium; Department of Anesthesia and Intensive Care Medicine, University Hospital Center Liege, Liege, Belgium; Anesthesia and Intensive Care Laboratory, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium.

Objective: The use of multicolumn-lead spinal cord stimulation (SCS) to control back pain (BP) and leg pain (LP) in patients with failed back surgery syndrome (FBSS) in the short term and mid-term has been well documented. Our study investigated whether SCS remained efficient after 72 months.

Methods: In an observational, single-center study, we assessed SCS efficacy in 62 patients with FBSS patients. BP, LP, and magnitude of daily activity limitation (DAL) were graded using a 0-10 visual analog scale (VAS) preoperatively and at 2, 6, 12, 24, 36, and 72 months after SCS implantation. Sleep quality, use of medications, and complications were also recorded.

Results: Of the 62 patients, 15 with complete follow-up data available were still using their SCS device at 72 months (SCS+). For these patients, the VAS scores for BP, LP, and DAL had changed from a median of 9 (interquartile range [IQR], 8.5-10), 7 (IQR, 6-8), and 8 (IQR, 8-9) preoperatively to a median of 4 (IQR, 3-4.5), 3 (IQR, 1.5-3.5), and 3 (IQR, 2-4) at 72 months. Their quality of sleep and analgesic medication consumption had also improved. In a subset of patients no longer using the SCS device after 72 months (SCS-), the VAS scores for BP, LP, and DAL, quality of sleep, and medication consumption were comparable to those for the SCS+ group. The SCS- group was less satisfied with the technique and were less professionally active than were the SCS+ group.

Conclusions: The SCS device provides sustained beneficial effects on BP, LP, DAL, sleep, and medication consumption in patients with FBSS still using it at 72 months postoperatively. Further studies are needed to identify the factors of adherence to the technique and the chances of success compared with the natural evolution of FBSS.
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http://dx.doi.org/10.1016/j.wneu.2020.06.181DOI Listing
October 2020

General Anesthesia: A Probe to Explore Consciousness.

Front Syst Neurosci 2019 14;13:36. Epub 2019 Aug 14.

Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liege, Liege, Belgium.

General anesthesia reversibly alters consciousness, without shutting down the brain globally. Depending on the anesthetic agent and dose, it may produce different consciousness states including a complete absence of subjective experience (unconsciousness), a conscious experience without perception of the environment (disconnected consciousness, like during dreaming), or episodes of oriented consciousness with awareness of the environment (connected consciousness). Each consciousness state may potentially be followed by explicit or implicit memories after the procedure. In this respect, anesthesia can be considered as a proxy to explore consciousness. During the recent years, progress in the exploration of brain function has allowed a better understanding of the neural correlates of consciousness, and of their alterations during anesthesia. Several changes in functional and effective between-region brain connectivity, consciousness network topology, and spatio-temporal dynamics of between-region interactions have been evidenced during anesthesia. Despite a set of effects that are common to many anesthetic agents, it is still uneasy to draw a comprehensive picture of the precise cascades during general anesthesia. Several questions remain unsolved, including the exact identification of the neural substrate of consciousness and its components, the detection of specific consciousness states in unresponsive patients and their associated memory processes, the processing of sensory information during anesthesia, the pharmacodynamic interactions between anesthetic agents, the direction-dependent hysteresis phenomenon during the transitions between consciousness states, the mechanisms of cognitive alterations that follow an anesthetic procedure, the identification of an eventual unitary mechanism of anesthesia-induced alteration of consciousness, the relationship between network effects and the biochemical or sleep-wake cycle targets of anesthetic agents, as well as the vast between-studies variations in dose and administration mode, leading to difficulties in between-studies comparisons. In this narrative review, we draw the picture of the current state of knowledge in anesthesia-induced unconsciousness, from insights gathered on propofol, halogenated vapors, ketamine, dexmedetomidine, benzodiazepines and xenon. We also describe how anesthesia can help understanding consciousness, we develop the above-mentioned unresolved questions, and propose tracks for future research.
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http://dx.doi.org/10.3389/fnsys.2019.00036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6703193PMC
August 2019

The Raw and Processed Electroencephalogram as a Monitoring and Diagnostic Tool.

J Cardiothorac Vasc Anesth 2019 08;33 Suppl 1:S3-S10

Anesthesia and Intensive Care Laboratory, GIGA-Consciousness Thematic Unit, GIGA Research, Liege University, Liège, Belgium. Electronic address:

In this narrative review, different aspects of electroencephalogram (EEG) monitoring during anesthesia are approached, with a special focus on cardiothoracic and vascular anesthesia, from the basic principles to more sophisticated diagnosis and monitoring utilities. The available processed EEG-derived indexes of the depth of the hypnotic component of anesthesia have well-defined limitations and usefulness. They prevent intraoperative awareness with recall in specific patient populations and under a specific anesthetic regimen. They prevent intraoperative overdose, and they shorten recovery times. They also help to avoid lengthy intraoperative periods of suppression activity, which are known to be deleterious in terms of outcome. Other than those available indexes, the huge amount of information contained in the EEG currently is being used only partially. Several other areas of interest regarding EEG during anesthesia have emerged in terms of anesthesia mechanisms elucidation, nociception monitoring, and diagnosis or prevention of brain insults.
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http://dx.doi.org/10.1053/j.jvca.2019.03.038DOI Listing
August 2019

Re-analysis of archaeobotanical remains from pre- and early agricultural sites provides no evidence for a narrowing of the wild plant food spectrum during the origins of agriculture in southwest Asia.

Veg Hist Archaeobot 2019 17;28(4):449-463. Epub 2018 Nov 17.

6Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN UK.

Archaeobotanical evidence from southwest Asia is often interpreted as showing that the spectrum of wild plant foods narrowed during the origins of agriculture, but it has long been acknowledged that the recognition of wild plants as foods is problematic. Here, we systematically combine compositional and contextual evidence to recognise the wild plants for which there is strong evidence of their deliberate collection as food at pre-agricultural and early agricultural sites across southwest Asia. Through sample-by-sample analysis of archaeobotanical remains, a robust link is established between the archaeological evidence and its interpretation in terms of food use, which permits a re-evaluation of the evidence for the exploitation of a broad spectrum of wild plant foods at pre-agricultural sites, and the extent to which this changed during the development of early agriculture. Our results show that relatively few of the wild taxa found at pre- and early agricultural sites can be confidently recognised as contributing to the human diet, and we found no evidence for a narrowing of the plant food spectrum during the adoption of agriculture. This has implications for how we understand the processes leading to the domestication of crops, and points towards a mutualistic relationship between people and plants as a driving force during the development of agriculture.
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http://dx.doi.org/10.1007/s00334-018-0702-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6551342PMC
November 2018

Changes in Whole Brain Dynamics and Connectivity Patterns during Sevoflurane- and Propofol-induced Unconsciousness Identified by Functional Magnetic Resonance Imaging.

Anesthesiology 2019 06;130(6):898-911

From the Department of Neurology (D.G., R.I.) Department of Anesthesiology (A.R., G.S., D.J.), Klinikum rechts der Isar, Technical University Munich, München, Germany GIGA-Consciousness, Coma Science Group (S.K.L., C.D.P., S.L.) GIGA-Consciousness, Sensation and Perception Research Group (A.V., V.B.) GIGA Research, University, and Department of Algology and Palliative Care, Department of Neurology (S.L.) Department of Anesthesia and Intensive Care Medicine (V.B.) CHU University Hospital of Liège (C.D.P.), Liège, Belgium GIGA-Cyclotron Research Center: In Vivo Imaging, University of Liège, Liège, Belgium (A.P.) University Department of Anesthesia and Intensive Care Medicine, CHR Citadelle, Liège, Belgium (V.B.) Department of Neurology, University of Wisconsin, Madison, Wisconsin (M.B.) Asklepios Clinic, Department of Neurology, Bad Tölz, Germany (R.I.).

Background: A key feature of the human brain is its capability to adapt flexibly to changing external stimuli. This capability can be eliminated by general anesthesia, a state characterized by unresponsiveness, amnesia, and (most likely) unconsciousness. Previous studies demonstrated decreased connectivity within the thalamus, frontoparietal, and default mode networks during general anesthesia. We hypothesized that these alterations within specific brain networks lead to a change of communication between networks and their temporal dynamics.

Methods: We conducted a pooled spatial independent component analysis of resting-state functional magnetic resonance imaging data obtained from 16 volunteers during propofol and 14 volunteers during sevoflurane general anesthesia that have been previously published. Similar to previous studies, mean z-scores of the resulting spatial maps served as a measure of the activity within a network. Additionally, correlations of associated time courses served as a measure of the connectivity between networks. To analyze the temporal dynamics of between-network connectivity, we computed the correlation matrices during sliding windows of 1 min and applied k-means clustering to the matrices during both general anesthesia and wakefulness.

Results: Within-network activity was decreased in the default mode, attentional, and salience networks during general anesthesia (P < 0.001, range of median changes: -0.34, -0.13). Average between-network connectivity was reduced during general anesthesia (P < 0.001, median change: -0.031). Distinct between-network connectivity patterns for both wakefulness and general anesthesia were observed irrespective of the anesthetic agent (P < 0.001), and there were fewer transitions in between-network connectivity patterns during general anesthesia (P < 0.001, median number of transitions during wakefulness: 4 and during general anesthesia: 0).

Conclusions: These results suggest that (1) higher-order brain regions play a crucial role in the generation of specific between-network connectivity patterns and their dynamics, and (2) the capability to interact with external stimuli is represented by complex between-network connectivity patterns.
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http://dx.doi.org/10.1097/ALN.0000000000002704DOI Listing
June 2019

Evoked Alpha Power is Reduced in Disconnected Consciousness During Sleep and Anesthesia.

Sci Rep 2018 11 9;8(1):16664. Epub 2018 Nov 9.

Department of Anesthesiology, University of Wisconsin, Madison, 53792, USA.

Sleep and anesthesia entail alterations in conscious experience. Conscious experience may be absent (unconsciousness) or take the form of dreaming, a state in which sensory stimuli are not incorporated into conscious experience (disconnected consciousness). Recent work has identified features of cortical activity that distinguish conscious from unconscious states; however, less is known about how cortical activity differs between disconnected states and normal wakefulness. We employed transcranial magnetic stimulation-electroencephalography (TMS-EEG) over parietal regions across states of anesthesia and sleep to assess whether evoked oscillatory activity differed in disconnected states. We hypothesized that alpha activity, which may regulate perception of sensory stimuli, is altered in the disconnected states of rapid eye movement (REM) sleep and ketamine anesthesia. Compared to wakefulness, evoked alpha power (8-12 Hz) was decreased during disconnected consciousness. In contrast, in unconscious states of propofol anesthesia and non-REM (NREM) sleep, evoked low-gamma power (30-40 Hz) was decreased compared to wakefulness or states of disconnected consciousness. These findings were confirmed in subjects in which dream reports were obtained following serial awakenings from NREM sleep. By examining signatures of evoked cortical activity across conscious states, we identified novel evidence that suppression of evoked alpha activity may represent a promising marker of sensory disconnection.
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http://dx.doi.org/10.1038/s41598-018-34957-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6226534PMC
November 2018

Two different methods to assess sympathetic tone during general anesthesia lead to different findings.

J Clin Monit Comput 2019 Jun 25;33(3):463-469. Epub 2018 Jun 25.

GIGA - Consciousness, Anesthesia and Intensive Care Medicine Laboratory, University and CHU University Hospital of Liege, Liege, Belgium.

Noxious stimulation influences the autonomic nervous system activity. Sympathetic tone monitoring is currently used to assess the adequacy of the balance between nociception and anti-nociception during general anesthesia. The Surgical Plethysmographic Index (SPI) and the EBMi software (Custos©) are commercial devices that use different algorithms to measure it. We aimed at determining whether those devices provide similar information during routine surgical procedures under general anesthesia. Data acquired during a previously published study in patients undergoing surgery under general anesthesia were retrospectively analyzed and passed through the EBMi software. The occurrence of EBMi alarms of increased sympathetic tone was compared to the occurrence of SPI values ≥ 60, a commonly recommended intraoperative SPI threshold. Trends in classical parameters of sympathetic tone during the 5 min preceding a SPI ≥ 60, namely blood pressure, heart rate, and plethysmographic pulse amplitude were assessed. SPI ≥ 60 episodes (n = 307) were more frequent than EBMi alerts (n = 240). Approximately 70% of EBMi alerts occurred during periods where the SPI was below 60. Among all episodes of SPI ≥ 60, absence of any EBMi alerts was much more frequent than the inverse. A majority, but not all SPI ≥ 60 episodes were consistently preceded by an increase in heart rate and/or a decrease in pulse amplitude. Blood pressure did not significantly change before SPI ≥ 60. Longer SPI ≥ 60 episodes were associated with lower anti-nociception anesthetic regimen. Different methods of sympathetic tone assessment during general anesthesia provide conflicting information. Prospective studies should be undertaken to clarify the clinical indications of both techniques.
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http://dx.doi.org/10.1007/s10877-018-0175-7DOI Listing
June 2019

Visual field shape and foraging ecology in diurnal raptors.

J Exp Biol 2018 07 17;221(Pt 14). Epub 2018 Jul 17.

CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE - 1919 route de Mende, 34293 Montpellier Cedex 5, France.

Birds, particularly raptors, are believed to forage primarily using visual cues. However, raptor foraging tactics are highly diverse - from chasing mobile prey to scavenging - which may reflect adaptations of their visual systems. To investigate this, we studied the visual field configuration of 15 species of diurnal Accipitriformes that differ in such tactics, first focusing on the binocular field and blind area by using a single-traits approach, and then exploring the shape of the binocular field with a morphometric approach. While the maximum binocular field width did not differ between species with different foraging tactics, the overall shape of their binocular fields did. In particular, raptors chasing terrestrial prey (ground predators) had a more protruding binocular field and a wider blind area above the head than did raptors chasing aerial or aquatic prey and obligate scavengers. Ground predators that forage on mammals from above have a wide but short bill - which increases ingestion rate - and a large suborbital ridge to avoid sun glare. This may explain the protruding binocular field and the wide blind area above the head. By contrast, species from the two other groups have long but narrow bills used to pluck, flake or tear food and may need large visual coverage (and reduced suborbital ridges) to increase their foraging efficiency (e.g. using large visual coverage to follow the escaping prey in three dimensions or detect conspecifics). We propose that binocular field shape is associated with bill and suborbital ridge shape and, ultimately, foraging strategies.
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http://dx.doi.org/10.1242/jeb.177295DOI Listing
July 2018

Comparison of clinical scores in their ability to detect hypoxemic severe OSA patients.

PLoS One 2018 7;13(5):e0196270. Epub 2018 May 7.

Department of Anesthesia, University of Liege, Liege, Belgium.

Background: Severe obstructive sleep apnea (sOSA) and preoperative hypoxemia are risk factors of postoperative complications. Patients exhibiting the combination of both factors are probably at higher perioperative risk. Four scores (STOP-Bang, P-SAP, OSA50, and DES-OSA) are currently used to detect OSA patients preoperatively. This study compared their ability to specifically detect hypoxemic sOSA patients.

Methods: One hundred and fifty-nine patients scheduled for an overnight polysomnography (PSG) were prospectively enrolled. The ability of the four scores to predict the occurrence of hypoxemic episodes in sOSA patients was compared using sensitivity (Se), specificity (Sp), Youden Index, Cohen kappa coefficient, and the area under ROC curve (AUROC) analyses.

Results: OSA50 elicited the highest Se [95% CI] at detecting hypoxemic sOSA patients (1 [0.89-1]) and was significantly more sensitive than STOP-Bang in that respect. DES-OSA was significantly more specific (0.58 [0.49-0.66]) than the three other scores. The Youden Index of DES-OSA (1.45 [1.33-1.58]) was significantly higher than those of STOP-Bang, P-SAP, and OSA50. The AUROC of DES-OSA (0.8 [0.71-0.89]) was significantly the largest. The highest Kappa value was obtained for DES-OSA (0.33 [0.21-0.45]) and was significantly higher than those of STOP-Bang, and OSA50.

Conclusions: In our population, DES-OSA appears to be more effective than the three other scores to specifically detect hypoxemic sOSA patients. However prospective studies are needed to confirm these findings in a perioperative setting.

Clinical Trial Registration: ClinicalTrials.gov: NCT02050685.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0196270PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5937788PMC
August 2018

Standardised noxious stimulation-guided individual adjustment of remifentanil target-controlled infusion to prevent haemodynamic responses to laryngoscopy and surgical incision: A randomised controlled trial.

Eur J Anaesthesiol 2018 03;35(3):173-183

Aline Defresne and Luc Barvais equally contributed to the article.

Background: The surgical plethysmographic index (SPI) is one of the available indexes of the nociception-antinociception (NAN) balance. Individually adjusting the NAN balance to prevent somatic responses to noxious stimulation remains a challenge.

Objectives: To assess whether guiding remifentanil administration according to the SPI response to a calibrated noxious stimulus (NANCAL) can blunt the haemodynamic response to tracheal intubation and surgical incision.

Design: Randomised multicentre study.

Setting: Two Belgian university hospitals from January 2014 to April 2015.

Patients: After ethic review board approval and informed consent, 48 American Society of Anesthesiologists I or II adult patients scheduled for surgery under general anaesthesia were enrolled.

Interventions: Patients were randomly assigned to a SPI group, where remifentanil effect-site concentration was adjusted according to NANCAL, or a control group, where it was fixed at 4 ng ml. Propofol concentration was always adjusted to maintain the bispectral index close to 40. NANCAL consisted of a 100 Hz, 60 mA electrical tetanic stimulation during 30 s at the wrist before tracheal intubation and before surgical incision.

Main Outcome Measures: The primary endpoint was the efficacy of the NANCAL-guided remifentanil administration to prevent the haemodynamic response to tracheal intubation and surgical incision. The secondary aim was to compare the ability of SPI, analgesia nociception index, pupil diameter and mean arterial pressure response to NANCAL to predict the haemodynamic response to tracheal intubation and surgical incision.

Results: Our SPI response to NANCAL-based correcting scheme for remifentanil administration was not superior to a fixed remifentanil concentration at blunting the haemodynamic response to tracheal intubation or surgical incision. Among all tested NAN balance indices, only mean arterial pressure had significant predictive ability with regard to the haemodynamic response to surgical incision.

Conclusion: Further research is needed to define the best NANCAL stimulus and the best remifentanil correcting scheme to help individualised tailoring of antinociception for each specific subpopulation of surgical patients.

Trial Registration: Clinicaltrials.gov NCT: 02884310; https://clinicaltrials.gov/ct2/show/NCT02884310.
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http://dx.doi.org/10.1097/EJA.0000000000000742DOI Listing
March 2018

Effect of Multicolumn Lead Spinal Cord Stimulation on Low Back Pain in Failed Back Surgery Patients: A Three-Year Follow-Up.

Neuromodulation 2017 Oct 2;20(7):668-674. Epub 2017 May 2.

Department of Neurosurgery, CHR Citadelle, Liège, Belgium.

Objectives: Spinal cord stimulation (SCS) remains poorly efficient at reducing back pain in failed back surgery syndrome (FBSS) patients. We aimed at determining whether a new multicolumn lead SCS technique was efficient at durably reducing their leg (LP) and back (BP) pain.

Materials And Methods: Sixty-two consecutive refractory FBSS patients received multicolumn SCS. Visual analogue scale (VAS) self-evaluation of BP, LP, and limitation of daily activity (LAD) were recorded preoperatively and at 2, 6, 12, 24, and 36 months after surgery. Quality of sleep and use of concomitant medications were also recorded.

Results: Complete datasets were obtained in 29 patients. BP (median VAS [25-75 centiles]) significantly decreased from 9 (8.5-10) preoperatively, to 3 (3-4) at short-term follow-up (2 months), and rose up to 5 (4-5) at 36 months. LP evolved from 7 (6-8) preoperatively, to 2.5 (2-3) at short-term follow-up, and 3 (2-3) at 36 months. Correspondingly, LAD VAS was 8 (8-9) preoperatively, and decreased to stable values of 3 (3-4) during the follow-up period. Quality of sleep also improved, with 72% of patients reporting poor sleep preoperatively to 0-7% in the follow-up period until 36 months. The percentages of patients regularly taking analgesic and/or co-analgesic medications decreased from 100% preoperatively to 8, 4, 12, 19, and 19%.

Conclusion: Multicolumn lead SCS in FBSS patients significantly improve BP, LP, quality of life, and medication consumption for at least 36 months. A classical placebo effect cannot account for long-term improvements of such magnitude.
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http://dx.doi.org/10.1111/ner.12603DOI Listing
October 2017

Mapping the functional connectome traits of levels of consciousness.

Neuroimage 2017 03 16;148:201-211. Epub 2017 Jan 16.

School of Industrial Engineering, Purdue University, West-Lafayette, IN, USA; Weldon School of Biomedical Engineering, Purdue University, West-Lafayette, IN, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West-Lafayette, IN, USA. Electronic address:

Examining task-free functional connectivity (FC) in the human brain offers insights on how spontaneous integration and segregation of information relate to human cognition, and how this organization may be altered in different conditions, and neurological disorders. This is particularly relevant for patients in disorders of consciousness (DOC) following severe acquired brain damage and coma, one of the most devastating conditions in modern medical care. We present a novel data-driven methodology, connICA, which implements Independent Component Analysis (ICA) for the extraction of robust independent FC patterns (FC-traits) from a set of individual functional connectomes, without imposing any a priori data stratification into groups. We here apply connICA to investigate associations between network traits derived from task-free FC and cognitive/clinical features that define levels of consciousness. Three main independent FC-traits were identified and linked to consciousness-related clinical features. The first one represents the functional configuration of a "resting" human brain, and it is associated to a sedative (sevoflurane), the overall effect of the pathology and the level of arousal. The second FC-trait reflects the disconnection of the visual and sensory-motor connectivity patterns. It also relates to the time since the insult and to the ability of communicating with the external environment. The third FC-trait isolates the connectivity pattern encompassing the fronto-parietal and the default-mode network areas as well as the interaction between left and right hemispheres, which are also associated to the awareness of the self and its surroundings. Each FC-trait represents a distinct functional process with a role in the degradation of conscious states of functional brain networks, shedding further light on the functional sub-circuits that get disrupted in severe brain-damage.
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http://dx.doi.org/10.1016/j.neuroimage.2017.01.020DOI Listing
March 2017

Incidence of Connected Consciousness after Tracheal Intubation: A Prospective, International, Multicenter Cohort Study of the Isolated Forearm Technique.

Anesthesiology 2017 02;126(2):214-222

From the Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin (R.D.S., A.R., C.B., A.H., R.M.B.); Department of Anesthesia, Rambam Healthcare Campus, Haifa, Israel (A.R.); Department of Anesthesiology and Critical Care, Houston Methodist Hospital, Houston, Texas (R.M.B.); Department of Anaesthesia, Waikato Clinical School, University of Auckland, Hamilton, New Zealand (A.G., J.W., J.S.); Department of Anesthesiology; University Hospital RWTH Aachen, Aachen, Germany (A.S., R.R., M.C.); Department of Anesthesia and Intensive Care Medicine, CHU University Hospital of Liège, Liège, Belgium (A.D., G.T., V.B.); University Department of Anesthesia and Intensive Care Medicine, CHR Citadelle and CHU University Hospital of Liège, Liège, Belgium (A.D., G.T., V.B.); Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands, (S.T., S.M., A.A.); and Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan (P.E.V., H.F., G.A.M.).

Background: The isolated forearm technique allows assessment of consciousness of the external world (connected consciousness) through a verbal command to move the hand (of a tourniquet-isolated arm) during intended general anesthesia. Previous isolated forearm technique data suggest that the incidence of connected consciousness may approach 37% after a noxious stimulus. The authors conducted an international, multicenter, pragmatic study to establish the incidence of isolated forearm technique responsiveness after intubation in routine practice.

Methods: Two hundred sixty adult patients were recruited at six sites into a prospective cohort study of the isolated forearm technique after intubation. Demographic, anesthetic, and intubation data, plus postoperative questionnaires, were collected. Univariate statistics, followed by bivariate logistic regression models for age plus variable, were conducted.

Results: The incidence of isolated forearm technique responsiveness after intubation was 4.6% (12/260); 5 of 12 responders reported pain through a second hand squeeze. Responders were younger than nonresponders (39 ± 17 vs. 51 ± 16 yr old; P = 0.01) with more frequent signs of sympathetic activation (50% vs. 2.4%; P = 0.03). No participant had explicit recall of intraoperative events when questioned after surgery (n = 253). Across groups, depth of anesthesia monitoring values showed a wide range; however, values were higher for responders before (54 ± 20 vs. 42 ± 14; P = 0.02) and after (52 ± 16 vs. 43 ± 16; P = 0.02) intubation. In patients not receiving total intravenous anesthesia, exposure to volatile anesthetics before intubation reduced the odds of responding (odds ratio, 0.2 [0.1 to 0.8]; P = 0.02) after adjustment for age.

Conclusions: Intraoperative connected consciousness occurred frequently, although the rate is up to 10-times lower than anticipated. This should be considered a conservative estimate of intraoperative connected consciousness.
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http://dx.doi.org/10.1097/ALN.0000000000001479DOI Listing
February 2017

Sedation of Patients With Disorders of Consciousness During Neuroimaging: Effects on Resting State Functional Brain Connectivity.

Anesth Analg 2017 02;124(2):588-598

From the *Coma Science Group and §MoVeRe Group, Cyclotron Research Center, University of Liège, Liège, Belgium; †Department of Anesthesia and Intensive Care Medicine, CHU Sart Tilman Hospital, University of Liège, Liège, Belgium; ‡Computer Imaging and Medical Applications Laboratory, National University of Colombia, Bogotá, Colombia; ‖Department of Neurology, CHU Sart Tilman Hospital University of Liège, Liège, Belgium; ¶Department of Algology and Palliative Care, University Hospital of Liège, University of Liège, Liège, Belgium; #Center for Sleep and Consciousness and Postle Laboratory, Department of Psychiatry, University of Wisconsin, Madison, Wisconsin; **Department of Physics and Astronomy, Brain & Mind Institute, University of Western Ontario, London, Ontario, Canada; and ††Department of Anesthesia and Intensive Care Medicine, CHR Citadelle and CHU Liège, University of Liège, Liège, Belgium.

Background: To reduce head movement during resting state functional magnetic resonance imaging, post-coma patients with disorders of consciousness (DOC) are frequently sedated with propofol. However, little is known about the effects of this sedation on the brain connectivity patterns in the damaged brain essential for differential diagnosis. In this study, we aimed to assess these effects.

Methods: Using resting state functional magnetic resonance imaging 3T data obtained over several years of scanning patients for diagnostic and research purposes, we employed a seed-based approach to examine resting state connectivity in higher-order (default mode, bilateral external control, and salience) and lower-order (auditory, sensorimotor, and visual) resting state networks and connectivity with the thalamus, in 20 healthy unsedated controls, 8 unsedated patients with DOC, and 8 patients with DOC sedated with propofol. The DOC groups were matched for age at onset, etiology, time spent in DOC, diagnosis, standardized behavioral assessment scores, movement intensities, and pattern of structural brain injury (as assessed with T1-based voxel-based morphometry).

Results: DOC were associated with severely impaired resting state network connectivity in all but the visual network. Thalamic connectivity to higher-order network regions was also reduced. Propofol administration to patients was associated with minor further decreases in thalamic and insular connectivity.

Conclusions: Our findings indicate that connectivity decreases associated with propofol sedation, involving the thalamus and insula, are relatively small compared with those already caused by DOC-associated structural brain injury. Nonetheless, given the known importance of the thalamus in brain arousal, its disruption could well reflect the diminished movement obtained in these patients. However, more research is needed on this topic to fully address the research question.
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http://dx.doi.org/10.1213/ANE.0000000000001721DOI Listing
February 2017

Resting-state Network-specific Breakdown of Functional Connectivity during Ketamine Alteration of Consciousness in Volunteers.

Anesthesiology 2016 11;125(5):873-888

From the University Department of Anesthesia and Intensive Care Medicine, CHR Citadelle and CHU University Hospital of Liege, Liege, Belgium (V.B., O.J.); Coma Science Group, GIGA Research, University and CHU University Hospital of Liege, Liege, Belgium (V.B., A.V., A.D., M.-A.B., M.A.B., S.L.); GIGA-Cyclotron Research Center: In Vivo Imaging, University of Liege, Liege, Belgium (A.V., A.D., M.-A.B., M.A.B., A.P., A.S., P.M., S.L.); Departments of Algology and Palliative Care (A.V.), Anesthesia and Intensive Care Medicine (V.B., O.J., P.B., J.F.B.), and Neurology (P.M., S.L.), CHU University Hospital of Liege, Liege, Belgium; Department of Neurology, University of Wisconsin, Madison, Wisconsin (M.B.); Departments of Anesthesia and Intensive Care Medicine (P.B.); Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada (A.S.); and Institut du Cerveau et de la Moelle épinière - ICM, Hôpital Pitié-Salpêtrière, Paris, France (A.D.).

Background: Consciousness-altering anesthetic agents disturb connectivity between brain regions composing the resting-state consciousness networks (RSNs). The default mode network (DMn), executive control network, salience network (SALn), auditory network, sensorimotor network (SMn), and visual network sustain mentation. Ketamine modifies consciousness differently from other agents, producing psychedelic dreaming and no apparent interaction with the environment. The authors used functional magnetic resonance imaging to explore ketamine-induced changes in RSNs connectivity.

Methods: Fourteen healthy volunteers received stepwise intravenous infusions of ketamine up to loss of responsiveness. Because of agitation, data from six subjects were excluded from analysis. RSNs connectivity was compared between absence of ketamine (wake state [W1]), light ketamine sedation, and ketamine-induced unresponsiveness (deep sedation [S2]).

Results: Increasing the depth of ketamine sedation from W1 to S2 altered DMn and SALn connectivity and suppressed the anticorrelated activity between DMn and other brain regions. During S2, DMn connectivity, particularly between the medial prefrontal cortex and the remaining network (effect size β [95% CI]: W1 = 0.20 [0.18 to 0.22]; S2 = 0.07 [0.04 to 0.09]), and DMn anticorrelated activity (e.g., right sensory cortex: W1 = -0.07 [-0.09 to -0.04]; S2 = 0.04 [0.01 to 0.06]) were broken down. SALn connectivity was nonuniformly suppressed (e.g., left parietal operculum: W1 = 0.08 [0.06 to 0.09]; S2 = 0.05 [0.02 to 0.07]). Executive control networks, auditory network, SMn, and visual network were minimally affected.

Conclusions: Ketamine induces specific changes in connectivity within and between RSNs. Breakdown of frontoparietal DMn connectivity and DMn anticorrelation and sensory and SMn connectivity preservation are common to ketamine and propofol-induced alterations of consciousness.
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http://dx.doi.org/10.1097/ALN.0000000000001275DOI Listing
November 2016

What mediates postoperative risk in obstructive sleep apnea: airway obstruction, nocturnal hypoxia, or both?

Can J Anaesth 2016 Sep 12;63(9):1104-5. Epub 2016 May 12.

Department of Anaesthesia, University of Liege, Liege, Belgium.

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http://dx.doi.org/10.1007/s12630-016-0667-1DOI Listing
September 2016

Different pitcher shapes and trapping syndromes explain resource partitioning in Nepenthes species.

Ecol Evol 2016 03 3;6(5):1378-92. Epub 2016 Feb 3.

Université de Montpellier UMR AMAP: botAnique et Modélisation de l'Architecture des Plantes et des végétations CIRAD - TA A51/PS2 Boulevard de la Lironde F-34398 Montpellier France; Université de Montpellier UMR 5554 Institut des Sciences de l'Evolution Place Eugène Bataillon F-34095 Montpellier France.

Nepenthes pitcher plants display interspecific diversity in pitcher form and diets. This species-rich genus might be a conspicuous candidate for an adaptive radiation. However, the pitcher traits of different species have never been quantified in a comparative study, nor have their possible adaptations to the resources they exploit been tested. In this study, we compare the pitcher features and prey composition of the seven Nepenthes taxa that grow in the heath forest of Brunei (Borneo) and investigate whether these species display different trapping syndromes that target different prey. The Nepenthes species are shown to display species-specific combinations of pitcher shapes, volumes, rewards, attraction and capture traits, and different degrees of ontogenetic pitcher dimorphism. The prey spectra also differ among plant species and between ontogenetic morphotypes in their combinations of ants, flying insects, termites, and noninsect guilds. According to a discriminant analysis, the Nepenthes species collected at the same site differ significantly in prey abundance and composition at the level of order, showing niche segregation but with varying degrees of niche overlap according to pairwise species comparisons. Weakly carnivorous species are first characterized by an absence of attractive traits. Generalist carnivorous species have a sweet odor, a wide pitcher aperture, and an acidic pitcher fluid. Guild specializations are explained by different combinations of morpho-functional traits. Ant captures increase with extrafloral nectar, fluid acidity, and slippery waxy walls. Termite captures increase with narrowness of pitchers, presence of a rim of edible trichomes, and symbiotic association with ants. The abundance of flying insects is primarily correlated with pitcher conicity, pitcher aperture diameter, and odor presence. Such species-specific syndromes favoring resource partitioning may result from local character displacement by competition and/or previous adaptations to geographically distinct environments.
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http://dx.doi.org/10.1002/ece3.1920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739188PMC
March 2016

Clinical pertinence and diagnostic accuracy of an evidence-based monitoring system: Custos.

Eur J Anaesthesiol 2016 08;33(8):590-2

From the University Department of Anaesthesia and ICM, CHR Citadelle and CHU Liege, Liege, Belgium (AD, VB); and Department of Surgery and Anaesthesia, University of Otago, Wellington, New Zealand (MH).

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http://dx.doi.org/10.1097/EJA.0000000000000425DOI Listing
August 2016

Large-scale signatures of unconsciousness are consistent with a departure from critical dynamics.

J R Soc Interface 2016 Jan;13(114):20151027

Coma Science Group, GIGA Research and Cyclotron Research Center, University and University Hospital of Liège, Liège, Belgium.

Loss of cortical integration and changes in the dynamics of electrophysiological brain signals characterize the transition from wakefulness towards unconsciousness. In this study, we arrive at a basic model explaining these observations based on the theory of phase transitions in complex systems. We studied the link between spatial and temporal correlations of large-scale brain activity recorded with functional magnetic resonance imaging during wakefulness, propofol-induced sedation and loss of consciousness and during the subsequent recovery. We observed that during unconsciousness activity in frontothalamic regions exhibited a reduction of long-range temporal correlations and a departure of functional connectivity from anatomical constraints. A model of a system exhibiting a phase transition reproduced our findings, as well as the diminished sensitivity of the cortex to external perturbations during unconsciousness. This framework unifies different observations about brain activity during unconsciousness and predicts that the principles we identified are universal and independent from its causes.
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http://dx.doi.org/10.1098/rsif.2015.1027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4759808PMC
January 2016

Positron Emission Tomography: Basic Principles, New Applications, and Studies Under Anesthesia.

Int Anesthesiol Clin 2016 ;54(1):109-28

*Department of Anesthesia and ICM, CHU Liege, Belgium †Coma Science Group-GGIGA Research, University of Liege, Belgium ‡Department of Neurology, CHU Liege, Belgium §University Department of Anesthesia and ICM, CHR Citadelle, Liege, Belgium.

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http://dx.doi.org/10.1097/AIA.0000000000000090DOI Listing
September 2016

Propofol-Induced Frontal Cortex Disconnection: A Study of Resting-State Networks, Total Brain Connectivity, and Mean BOLD Signal Oscillation Frequencies.

Brain Connect 2016 Apr 7;6(3):225-37. Epub 2016 Mar 7.

4 Department of Physics and Astronomy, Brain and Mind Institute, University of Western Ontario , London, Ontario, Canada .

Propofol is one of the most commonly used anesthetics in the world, but much remains unknown about the mechanisms by which it induces loss of consciousness. In this resting-state functional magnetic resonance imaging study, we examined qualitative and quantitative changes of resting-state networks (RSNs), total brain connectivity, and mean oscillation frequencies of the regional blood oxygenation level-dependent (BOLD) signal, associated with propofol-induced mild sedation and loss of responsiveness in healthy subjects. We found that detectability of RSNs diminished significantly with loss of responsiveness, and total brain connectivity decreased strongly in the frontal cortex, which was associated with increased mean oscillation frequencies of the BOLD signal. Our results suggest a pivotal role of the frontal cortex in propofol-induced loss of responsiveness.
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http://dx.doi.org/10.1089/brain.2015.0369DOI Listing
April 2016

Development and Validation of a Morphologic Obstructive Sleep Apnea Prediction Score: The DES-OSA Score.

Anesth Analg 2016 Feb;122(2):363-72

From the *Department of Anesthesia, Clinique Saint-Luc and Cabinet Medical ASTES, Namur, Belgium; †Cabinet Medical ASTES, Namur, Belgium; ‡Department of Anesthesia and ICM, CHU Liege, Liege, Belgium; §Department of Neurology, CHU Liege, Liege, Belgium; and ‖Department of Anesthesia and ICM, CHR Citadelle and CHU Liege, Liege, Belgium.

Background: Obstructive sleep apnea (OSA) is a common and underdiagnosed entity that favors perioperative morbidity. Several anatomical characteristics predispose to OSA. We developed a new clinical score that would detect OSA based on the patient's morphologic characteristics only.

Methods: Patients (n = 149) scheduled for an overnight polysomnography were included. Their morphologic metrics were compared, and combinations of them were tested for their ability to predict at least mild, moderate-to-severe, or severe OSA, as defined by an apnea-hypopnea index (AHI) >5, >15, or >30 events/h. This ability was calculated using Cohen κ coefficient and prediction probability.

Results: The score with best prediction abilities (DES-OSA score) considered 5 variables: Mallampati score, distance between the thyroid and the chin, body mass index, neck circumference, and sex. Those variables were weighted by 1, 2, or 3 points. DES-OSA score >5, 6, and 7 were associated with increased probability of an AHI >5, >15, or >30 events/h, respectively, and those thresholds had the best Cohen κ coefficient, sensitivities, and specificities. Receiver operating characteristic curve analysis revealed that the area under the curve was 0.832 (95% confidence interval [CI], 0.762-0.902), 0.805 (95% CI, 0.734-0.876), and 0.834 (95% CI, 0.757-0.911) for DES-OSA at predicting an AHI >5, >15, and >30 events/h, respectively. With the aforementioned thresholds, corresponding sensitivities (95% CI) were 82.7% (74.5-88.7), 77.1% (66.9-84.9), and 75% (61.0-85.1), and specificities (95% CI) were 72.4% (54.0-85.4), 73.2% (60.3-83.1), and 76.9% (67.2-84.4). Validation of DES-OSA performance in an independent sample yielded highly similar results.

Conclusions: DES-OSA is a simple score for detecting OSA patients. Its originality relies on its morphologic nature. Derived from a European population, it may prove useful in a preoperative setting, but it has still to be compared with other screening tools in a general surgical population and in other ethnic groups.
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http://dx.doi.org/10.1213/ANE.0000000000001089DOI Listing
February 2016