Research LettersRestoration of thalamocortical connectivity after recovery from persistent vegetative state
Summary
By use of H215O positron emission tomography we have shown that functional connectivity between intralaminar thalamic nuclei and prefrontal and anterior cingulate cortices was altered during vegetative state but not after recovery of consciousness.
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Cited by (325)
Neuroimaging in Disorders of Consciousness and Recovery
2024, Physical Medicine and Rehabilitation Clinics of North AmericaEvaluating the effect of spinal cord stimulation on patient with disorders of consciousness: A TMS-EEG study
2023, Computers in Biology and MedicineThe application of spinal cord stimulation (SCS) in the treatment of disorders of consciousness (DOC) has attracted attention, but its effect on brain activity is still unknown. Transcranial magnetic stimulation combined with EEG (TMS-EEG) can measure cortical activity, which can evaluate the effect of SCS on DOC.
We record 20 DOC patients' CRS-R values and TMS-EEG data before and after one-session SCS (Pre-SCS and Post-SCS). 20 DOC patients including 10 patients with unresponsive wakefulness syndrome (UWS) and 10 patients with minimally conscious states (MCS). TMS evoked potential (TEP) was used to measure the changes of cortical activity in DOC patients between Pre-SCS and Post-SCS. Firstly, we used the global mean field potential (GMFP) and fast perturbational complexity index (PCIst) to compare the temporal changes of patients' cortical activity. Then, we obtained the frequency feature (natural frequency, NF) based on the TEP time-frequency analysis, and compared the changes of natural frequency between Pre-SCS and Post-SCS. Finally, the study explored the relationship between the patient's baseline CRS-R values and changes of TMS evoked cortical activity in time and frequency domains.
After SCS, MCS and UWS groups almost have no changes of CRS-R values (MCS: 9.9 ± 1.52 at Pre-SCS, 10.2 ± 1.48 at Post-SCS; UWS: 5.6 ± 1.26 at Pre-SCS, 5.7 ± 1.34 at Post-SCS). MCS group showed significant increases of GMFP amplitude (around 100 ms and 300 ms) and PCIst values at Post-SCS (p < 0.05). UWS group had no significant changes (p > 0.05). Besides, SCS induced the significant increases of natural frequency for MCS group(p < 0.05), but not for UWS group. At last, the study found that all patient's baseline CRS-R values were significantly correlated with ΔPCIst (r = 0.67, p < 0.005), and ΔNF (r = 0.72, p < 0.001).
SCS can modulate cortical activity of DOC patient, including temporal complexity and natural frequency. The changes of cortical activity caused by SCS are related to patients’ consciousness level. TMS-EEG can evaluate the effect of SCS on DOC patients.
Electrophysiological characteristics of CM-pf in diagnosis and outcome of patients with disorders of consciousness
2023, Brain StimulationDeep brain stimulation (DBS) in the centromedian-parafascicular complex (CM-pf) has been reported as a potential therapeutic option for disorders of consciousness (DoC). However, the lack of understanding of its electrophysiological characteristics limits the improvement of therapeutic effect.
To investigate the CM-pf electrophysiological characteristics underlying disorders of consciousness (DoC) and its recovery.
We collected the CM-pf electrophysiological signals from 23 DoC patients who underwent central thalamus DBS (CT-DBS) surgery. Five typical electrophysiological features were extracted, including neuronal firing properties, multiunit activity (MUA) properties, signal stability, spike-MUA synchronization strength (syncMUA), and the background noise level. Their correlations with the consciousness level, the outcome, and the primary clinical factors of DoC were analyzed.
11 out of 23 patients (0/2 chronic coma, 5/13 unresponsive wakefulness syndrome/vegetative state (UWS/VS), 6/8 minimally conscious state minus (MCS-)) exhibited an improvement in the level of consciousness after CT-DBS. In CM-pf, significantly stronger gamma band syncMUA strength and alpha band normalized MUA power were found in MCS- patients. In addition, higher firing rates, stronger high-gamma band MUA power and alpha band normalized power, and more stable theta oscillation were correlated with better outcomes. Besides, we also identified electrophysiological properties that are correlated with clinical factors, including etiologies, age, and duration of DoC.
We provide comprehensive analyses of the electrophysiological characteristics of CM-pf in DoC patients. Our results support the ‘mesocircuit’ hypothesis, one proposed mechanism of DoC recovery, and reveal CM-pf electrophysiological features that are crucial for understanding the pathogenesis of DoC, predicting its recovery, and explaining the effect of clinical factors on DoC.
Structural connectivity in recovery after coma: Connectome atlas approach
2023, NeuroImage: ClinicalPathological states of recovery after coma as a result of a severe brain injury are marked with changes in structural connectivity of the brain. This study aimed to identify a topological correlation between white matter integrity and the level of functional and cognitive impairment in patients recovering after coma.
Structural connectomes were computed based on fractional anisotropy maps from 40 patients using a probabilistic human connectome atlas. We used a network based statistics approach to identify potential brain networks associated with a more favorable outcome, assessed with clinical neurobehavioral scores at the patient’s discharge from the acute neurorehabilitation unit.
We identified a subnetwork whose strength of connectivity correlated with a more favorable outcome as measured with the Disability Rating Scale (network based statistics: t >3.5, P =.010). The subnetwork predominated in the left hemisphere and included the thalamic nuclei, putamen, precentral and postcentral gyri, and medial parietal regions. Spearman correlation between the mean fractional anisotropy value of the subnetwork and the score was ρ = −0.60 (P <.0001). A less extensive overlapping subnetwork correlated with the Coma Recovery Scale Revised score, consisting mostly of the left hemisphere connectivity between the thalamic nuclei and pre- and post-central gyri (network based statistics: t >3.5, P =.033; Spearman’s ρ = 0.58, P <.0001).
The present findings suggest an important role of structural connectivity between the thalamus, putamen and somatomotor cortex in the recovery from coma as evaluated with neurobehavioral scores. These structures are part of the motor circuit involved in the generation and modulation of voluntary movement, as well as the forebrain mesocircuit supposedly underlying the maintenance of consciousness. As behavioural assessment of consciousness depends heavily on the signs of voluntary motor behaviour, further work will elucidate whether the identified subnetwork reflects the structural architecture underlying the recovery of consciousness or rather the ability to communicate its content.
Detecting residual brain networks in disorders of consciousness: A resting-state fNIRS study
2023, Brain ResearchFunctional near infrared spectroscopy (fNIRS) is an emerging non-invasive technique that allows bedside measurement of blood oxygenation level-dependent hemodynamic signals. We aimed to examine the efficacy of resting-state fNIRS in detecting the residual functional networks in patients with disorders of consciousness (DOC). We performed resting-state fNIRS in 23 DOC patients of whom 12 were in minimally conscious state (MCS) and 11 were in unresponsive wakefulness state (UWS). Ten regions of interest (ROIs) in the prefrontal cortex (PFC) were selected: both sides of Brodmann area (BA) 9, BA10, BA44, BA45, and BA46. Graph-theoretical analysis and seed-based correlation analyses were used to investigate the network topology and the strength of pairwise connections between ROIs and channels. MCS and UWS exhibited varying degrees of the loss of topological architecture, and the regional nodal properties of BA10 were significantly different between them (Nodal degree, PLeft BA10 = 0.01, PRight BA10 < 0.01; nodal efficiency, PLeft BA10 = 0.03, PRight BA10 < 0.01). Compared to healthy controls, UWS had impaired functions in both short- and long-distance connectivity, however, MCS had significantly impaired functions only in long-distance connectivity. The functional connectivity of right BA10 (AUC = 0.88) and the connections between left BA46 and right BA10 (AUC = 0.86) had excellent performance in differentiating MCS and UWS. MCS and UWS have different patterns of topological architecture and short- and long-distance connectivity in PFC. Intraconnections within BA10 and interhemispheric connections between BA10 and 46 are excellent resting-state fNIRS classifiers for distinguishing between MCS and UWS.
Neural correlates of consciousness and related disorders: From phenotypic descriptors of behavioral and relative consciousness to cortico-subcortical circuitry
2022, NeurochirurgieWe report a review of medical aspects of the consciousness. The behavioral dimension, phenotypic descriptors, relative consciousness and neural correlates of consciousness and related disorders were addressed successively in a holistic and chronological approach. Consciousness is relative, specific to each individual across time and space. Historically defined as the perception of the self and the environment, it cannot be separated from behaviors, entailing an idea of conscious behavior with metapractic and metagnostic aspects. Observation of spontaneous and evoked overt behavior distinguishes three main types of disorder of consciousness (DoC): coma, vegetative state or unresponsive wakefulness, and minimally conscious or relationally impoverished state. Modern functional exploration techniques, such as imaging, increase the understanding of DoCs and consciousness. Whether consciousness is a superior function and/or an instrumental function is discussed. Neural correlates can be subdivided into two wakefulness pathways (superior thalamic cholinergic and inferior extra-thalamic), and cortico-subcortical circuitry. The deep brain structures are those described in the well-known sensorimotor, associative and limbic loops, as illustrated in the mesolimbic model of DoC. The cortices can be segregated into several overlapping networks: (1) a global workspace including thalamo-cortical loops; (2) the default mode network (DMN) and related intrinsic connectivity networks (i.e., central executive, medial DMN and salience networks); (3) a 3-fold network comprising the fronto-parietal control system and its dorsal and ventral attentional sub-networks, the fronto-parietal executive control network, and the cingulo-opercular salience network; (4) the internal and external cortices, respectively medial, turned toward the self, and lateral, turned toward the environment. The network dynamics is the reflection of consciousness, notably anticorrelations such as the decrease in activity of the posterior cingulate-precuneus regions during attentional tasks. Thanks to recent advances in DoC pathophysiology, further significative therapeutic progress is expected, taking into account the societal context. This depends notably on the dissemination of medical knowledge and its transfer to a wider public.
Nous rapportons une revue des aspects médicaux de la conscience. La dimension comportementale, des descripteurs phénotypiques, la conscience relative et les corrélats neuronaux de la conscience et de ses troubles ont été abordés successivement selon une approche holistique et chronologique. La conscience est relative, spécifique à chacun, dans le temps et l’espace. Historiquement définie comme la perception de soi et de l’environnement, elle ne peut être séparée des comportements, ce qui implique la notion de comportements conscients avec des aspects méta-praxiques et méta-gnosiques. L’observation de comportements spontanés ou provoqués permet de définir trois types de troubles de la conscience, le coma, l’état végétatif ou éveillé non-répondant, et l’état de conscience minimale ou pauci-relationnel. Des techniques modernes d’exploration fonctionnelle, comme l’imagerie, améliorent la compréhension de la conscience et de ses troubles. Le fait que la conscience soit une fonction supérieure et/ou une fonction instrumentale est discuté. Les corrélats neuronaux peuvent se subdiviser selon deux voies de l’éveil, la voie supérieure cholinergique thalamique et la voie inférieure extra-thalamique, et en une circuiterie cortico-sous-corticale. Les structures du cerveau profond sont celles décrites dans les boucles, bien connues, sensorimotrices, associatives et limbiques, comme illustré dans le modèle mésolimbique des troubles de la conscience. Les cortex peuvent être distingués selon leur appartenance à plusieurs réseaux se chevauchant : (1) un réseau global incluant des boucles thalamo-corticales ; (2) le réseau du mode par défaut et les réseaux intrinsèques liés, soit le central exécutif, le réseau par défaut médial et la saillance ; (3) un triple model de réseau avec le système fronto-pariétal de contrôle et ses sous-réseaux dorsal et ventral attentionnels, le réseau fronto-pariétal exécutif de contrôle et le réseau cingulo-operculaire de saillance ; (4) les cortex internes et externes, respectivement médiaux tournés vers le soi, et latéraux tournés vers l’environnement. La dynamique des réseaux est le reflet de la conscience, notamment les anti-corrélations comme la baisse d’activité de la région cingulaire postérieure et de celle pré-cunéale durant les tâches attentionnelles. Grâce aux avancées récentes sur la physiopathologie des troubles de la conscience, de futurs progrès thérapeutiques significatifs, adaptés au contexte sociétal, sont espérés. Ceci dépend notamment de la divulgation de la connaissance médicale et de son transfert au grand public.