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Disruption of transfer entropy and inter-hemispheric brain functional connectivity in patients with disorder of consciousness  [PDF]
Verónica M?ki-Marttunen,Ibai Diez,Jesus M. Cortes,Dante R. Chialvo,Mirta Villarreal
Frontiers in Neuroinformatics , 2013, DOI: 10.3389/fninf.2013.00024
Abstract: Severe traumatic brain injury can lead to disorders of consciousness (DOC) characterized by deficit in conscious awareness and cognitive impairment including coma, vegetative state, minimally consciousness, and lock-in syndrome. Of crucial importance is to find objective markers that can account for the large-scale disturbances of brain function to help the diagnosis and prognosis of DOC patients and eventually the prediction of the coma outcome. Following recent studies suggesting that the functional organization of brain networks can be altered in comatose patients, this work analyzes brain functional connectivity (FC) networks obtained from resting-state functional magnetic resonance imaging (rs-fMRI). Two approaches are used to estimate the FC: the Partial Correlation (PC) and the Transfer Entropy (TE). Both the PC and the TE show significant statistical differences between the group of patients and control subjects; in brief, the inter-hemispheric PC and the intra-hemispheric TE account for such differences. Overall, these results suggest two possible rs-fMRI markers useful to design new strategies for the management and neuropsychological rehabilitation of DOC patients.
Disruption of transfer entropy and inter-hemispheric brain functional connectivity in patients with disorder of consciousness  [PDF]
Verónica M?ki-Marttunen,Ibai Diez,Jesus M. Cortes,Dante R. Chialvo,Mirta Villarreal
Quantitative Biology , 2013,
Abstract: Severe traumatic brain injury can lead to disorders of consciousness (DOC) characterized by deficit in conscious awareness and cognitive impairment including coma, vegetative state, minimally consciousness, and lock-in syndrome. Of crucial importance is to find objective markers that can account for the large-scale disturbances of brain function to help the diagnosis and prognosis of DOC patients and eventually the prediction of the coma outcome. Following recent studies suggesting that the functional organization of brain networks can be altered in comatose patients, this work analyzes brain functional connectivity (FC) networks obtained from resting-state functional magnetic resonance imaging (rs-fMRI). Two approaches are used to estimate the FC: the Partial Correlation (PC) and the Transfer Entropy (TE). Both the PC and the TE show significant statistical differences between the group of patients and control subjects; in brief, the inter-hemispheric PC and the intra-hemispheric TE account for such differences. Overall, these results suggest two possible rs-fMRI markers useful to design new strategies for the management and neuropsychological rehabilitation of DOC patients.
Reduced Fractional Anisotropy of Corpus Callosum Modulates Inter-Hemispheric Resting State Functional Connectivity in Migraine Patients without Aura  [PDF]
Kai Yuan, Wei Qin, Peng Liu, Ling Zhao, Dahua Yu, Limei Zhao, Minghao Dong, Jixin Liu, Xuejuan Yang, Karen M. von Deneen, Fanrong Liang, Jie Tian
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045476
Abstract: Background Diffusion tensor imaging (DTI) study revealed reduced fractional anisotropy (FA) values in the corpus callosum (CC) in migraine patients without aura. Abnormalities in white matter integrity, particularly in the CC, may affect inter-hemispheric resting state functional connectivity (RSFC). Unfortunately, relatively little is known about the alterations in functional interactions between the cerebral hemispheres during resting state in migraine patients without aura, and even less about how the inter-hemispheric RSFC are affected by the abnormalities of the CC. Methods and findings Twenty-one migraine patients without aura and 21 healthy controls participated in this study, age-, sex-, and education-matched. Tract-based spatial statistics (TBSS) was employed to investigate the white matter alterations of the CC. Meanwhile, voxel-mirrored homotopic connectivity (VMHC) was used to compare the inter-hemispheric RSFC differences between the patients and controls. TBSS analysis revealed reduced FA values in the genu and the splenium of CC in patient group. VMHC analysis showed decreased inter-hemispheric RSFC of anterior cingulate cortex (ACC) in migraine patients without aura relative to that of the controls. Furthermore, in migraine patients without aura, the reduced FA values of the genu of CC correlated with the decreased inter-hemispheric RSFC of the ACC. Conclusions Our findings demonstrated that the migraine patients without aura showed reduced FA values of the genu of CC and decreased inter-hemispheric RSFC of the ACC. The correlation between the above structural and functional changes suggested that the reduced fractional anisotropy (FA) of CC modulates inter-hemispheric VMHC in migraine patients without aura. Our results demonstrated that the VMHC alterations of ACC can reflect the FA changes of the genu of CC in migraine patients without aura.
Stroke and Disorders of Consciousness
Zikrija Dostovi ,D evdet Smajlovi ,Ernestina Dostovi ,Omer . Ibrahimagi
Cardiovascular Psychiatry and Neurology , 2012, DOI: 10.1155/2012/429108
Abstract: Objectives. To determine the severity of stroke and mortality in relation to the type of disturbance of consciousness and outcome of patients with disorders of consciousness. Patients and Methods. We retrospectively analyzed 201 patients. Assessment of disorders of consciousness is performed by Glasgow Coma Scale (Teasdale and Jennet, 1974) and the Diagnostic and Statistical Manual of Mental Disorders (Anonymous, 2000). The severity of stroke was determined by National Institutes of Health Stroke Scale (Lyden et al., 2011). Results. Fifty-four patients had disorders of consciousness (26.9%). Patients with disorders of consciousness on admission (<0.001) and discharge (=0.003) had a more severe stroke than patients without disturbances of consciousness. Mortality was significantly higher in patients with disorders of consciousness (=0.0001), and there was no difference in mortality in relation to the type of disturbance of consciousness. There is no statistically significant effect of specific predictors of survival in patients with disorders of consciousness. Conclusion. Patients with disorders of consciousness have a more severe stroke and higher mortality. There is no difference in mortality and severity of stroke between patients with quantitative and qualitative disorders of consciousness. There is no statistically significant effect of specific predictors of survival in patients with disorders of consciousness.
Mindsight: Diagnostics in Disorders of Consciousness  [PDF]
P. Guldenmund,J. Stender,L. Heine,S. Laureys
Critical Care Research and Practice , 2012, DOI: 10.1155/2012/624724
Abstract: Diagnosis of patients with disorders of consciousness (comprising coma, vegetative state/unresponsive wakefulness syndrome, and minimally conscious state) has long been dependent on unstandardized behavioral tests. The arrival of standardized behavioral tools, and especially the Coma Recovery Scale revised, uncovered a high rate of misdiagnosis. Ancillary techniques, such as brain imaging and electrophysiological examinations, are ever more often being deployed to aid in the search for remaining consciousness. They are used to look for brain activity patterns similar to those found in healthy controls. The development of portable and cheaper devices will make these techniques more widely available. 1. Introduction Recent advances in medicine have led to an increase in survival rate after severe brain damage [1]. Many of the survivors pass into states of disorders of consciousness (DOC), such as coma, unresponsive wakefulness syndrome (UWS, previously known as vegetative state (VS); [2]), or the minimally conscious state (MCS) (Figure 1). In this paper, we will discuss the differential diagnosis of these patients using clinical and ancillary methods. Coma is defined as absence of both arousal and responsiveness and usually lasts no longer than four weeks. Patients in a coma can recover or transit to the VS/UWS or MCS or can become locked-in: a state of near-complete body paralysis in which consciousness is fully recovered but possibilities for communication are generally restricted to eye movement and blinking [3]. In contrast, VS/UWS patients show no behavioral sign of awareness, but have retained some level of arousal. They show eye-opening, have sleep-wake cycles, and are able to maintain vital functions unassisted [4]. VS/UWS patients may show reflex responses to tactile, pain, auditive, or visual stimuli, but fail to show response to commands. The recent renaming of the “vegetative state” into UWS has multiple reasons. Firstly, UWS gives a better description of the behavior profile in which the patient is awake, but nonresponsive. Secondly, it has less negative connotation, as a vegetative state could be associated with the patient being “vegetable-like” [2]. The VS/UWS can be a permanent state or can evolve to the MCS. The MCS is characterized by inconsistent, nonreflexive behavior indicating a form of fluctuating low-level awareness [5]. Brain imaging techniques and behavioral assessments indicate that these patients do feel pain and emotions, as will be discussed later in this review. The MCS has recently been stratified into MCS+ (plus) and MCS?
Spectral Signatures of Reorganised Brain Networks in Disorders of Consciousness  [PDF]
Srivas Chennu ,Paola Finoia,Evelyn Kamau,Judith Allanson,Guy B. Williams,Martin M. Monti,Valdas Noreika,Aurina Arnatkeviciute,Andrés Canales-Johnson,Francisco Olivares,Daniela Cabezas-Soto,David K. Menon,John D. Pickard,Adrian M. Owen,Tristan A. Bekinschtein
PLOS Computational Biology , 2014, DOI: doi/10.1371/journal.pcbi.1003887
Abstract: Theoretical advances in the science of consciousness have proposed that it is concomitant with balanced cortical integration and differentiation, enabled by efficient networks of information transfer across multiple scales. Here, we apply graph theory to compare key signatures of such networks in high-density electroencephalographic data from 32 patients with chronic disorders of consciousness, against normative data from healthy controls. Based on connectivity within canonical frequency bands, we found that patient networks had reduced local and global efficiency, and fewer hubs in the alpha band. We devised a novel topographical metric, termed modular span, which showed that the alpha network modules in patients were also spatially circumscribed, lacking the structured long-distance interactions commonly observed in the healthy controls. Importantly however, these differences between graph-theoretic metrics were partially reversed in delta and theta band networks, which were also significantly more similar to each other in patients than controls. Going further, we found that metrics of alpha network efficiency also correlated with the degree of behavioural awareness. Intriguingly, some patients in behaviourally unresponsive vegetative states who demonstrated evidence of covert awareness with functional neuroimaging stood out from this trend: they had alpha networks that were remarkably well preserved and similar to those observed in the controls. Taken together, our findings inform current understanding of disorders of consciousness by highlighting the distinctive brain networks that characterise them. In the significant minority of vegetative patients who follow commands in neuroimaging tests, they point to putative network mechanisms that could support cognitive function and consciousness despite profound behavioural impairment.
Music in disorders of consciousness  [PDF]
Jens D. Rollnik,Eckart Altenmüller
Frontiers in Neuroscience , 2014, DOI: 10.3389/fnins.2014.00190
Abstract: This review presents an overview of the use of music therapy in neurological early rehabilitation of patients with coma and other disorders of consciousness (DOC) such as unresponsive wakefulness syndrome (UWS) or minimally conscious state (MCS). There is evidence that patients suffering from UWS show emotional processing of auditory information, such as listening to speech. Thus, it seems reasonable to believe that music listening – as part of an enriched environment setting – may be of therapeutic value in these patients. There is, however, a considerable lack of evidence. The authors strongly encourage further studies to evaluate the efficacy of music listening in patients with DOC in neurological early rehabilitation. These studies should consider a precise clinical definition and homogeneity of the patient cohort with respect to the quality (coma vs. UWS vs. MCS), duration (rather weeks to months than days) and cause (traumatic vs. non-traumatic) of DOC, a standardised intervention protocol, valid clinical outcome parameters over a longer observation period (weeks to months), monitoring of neurophysiological and vegetative parameters and, if available, neuroimaging to confirm diagnosis and to demonstrate responses and functional changes in the patients` brains.
The Capabilities of the EISCAT Svalbard Radar for Inter-hemispheric Coordinated Studies  [PDF]
Tom Grydeland,Anja Str?mme,Tony van Eyken,Cesar La Hoz
Physics , 2004,
Abstract: In this article we want to present the EISCAT Svalbard Radar (ESR) in some detail, as well as some of the instruments of interest for ionospheric and magnetospheric research that are located in the vicinity of it. We particularly describe how this instrument cluster, close to the geomagnetic conjugate point of the Chinese Antarctic Zhongshan station, can contribute to inter-hemispheric coordinated studies of the polar Ionosphere.
Long distance communication in the human brain: timing constraints for inter-hemispheric synchrony and the origin of brain lateralization
ABOITIZ,FRANCISCO; LóPEZ,JAVIER; MONTIEL,JUAN;
Biological Research , 2003, DOI: 10.4067/S0716-97602003000100007
Abstract: analysis of corpus callosum fiber composition reveals that inter-hemispheric transmission time may put constraints on the development of inter-hemispheric synchronic ensembles, especially in species with large brains like humans. in order to overcome this limitation, a subset of large-diameter callosal fibers are specialized for fast inter-hemispheric transmission, particularly in large-brained species. nevertheless, the constraints on fast inter-hemispheric communication in large-brained species can somehow contribute to the development of ipsilateral, intrahemispheric networks, which might promote the development of brain lateralization.
Long distance communication in the human brain: timing constraints for inter-hemispheric synchrony and the origin of brain lateralization  [cached]
FRANCISCO ABOITIZ,JAVIER LóPEZ,JUAN MONTIEL
Biological Research , 2003,
Abstract: Analysis of corpus callosum fiber composition reveals that inter-hemispheric transmission time may put constraints on the development of inter-hemispheric synchronic ensembles, especially in species with large brains like humans. In order to overcome this limitation, a subset of large-diameter callosal fibers are specialized for fast inter-hemispheric transmission, particularly in large-brained species. Nevertheless, the constraints on fast inter-hemispheric communication in large-brained species can somehow contribute to the development of ipsilateral, intrahemispheric networks, which might promote the development of brain lateralization.
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