Outcome prediction for patients with disorders of consciousness (DOC) is essential yet challenging. Evidence showed that patients with DOC lasting 1 year or longer after a brain injury were less ...likely to recover. However, the reasons why outcomes of DOC patients differ greatly remain unclear. With a variety of analytical methods and through quantitative behavioral assessments, we aimed to track the progression of a patient with severe brain injury, in order to advance our understanding of the underlying mechanisms of DOC.
We performed a longitudinal study for a 52-year-old male DOC patient who has remained in the state for 1.5 years with comprehensive rehabilitative therapies. The patient underwent 3 times of assessments of Coma Recovery Scale-Revised (CRS-R) and ultra-high-field 7 T magnetic resonance imaging (MRI). Both topologic properties and brain microstructure were analyzed to track disease progression. We observed dynamic increases of fiber densities with measurements at three time points (t1:1.5 M, t2:7.5 M t3:17.5 M). Specifically, fiber densities of the superior longitudinal fasciculus and arcuate fasciculus nerve fiber bundles improved mostly in the visual, verbal, and auditory subscales, which was consistent with the CRS-R scores. Moreover, the graph-theory analyses demonstrated that network topologic properties showed an improvement although the disease duration exceeded 1 year.
DOC patients with a course longer than 1 year remain possible to improve, and including evaluation methods such as WM connectome analysis and graph theory could be potentially valuable for a more precise assessment of patients with a longer course of DOC.
Our ability to identify covert cognitive abilities in non-communicating patients is of prime importance to improve diagnosis, to guide therapeutic decisions and to better predict their cognitive ...outcome. In the present study, we used a basic and rigorous paradigm contrasting pairs of words orthogonally. This paradigm enables the probing of semantic processing by comparing neural activity elicited by similar words delivered in various combinations. We describe the respective timing, topography and estimated cortical sources of two successive event-related potentials (ERP) components (N400 and late positive component (LPC)) using high-density EEG in conscious controls (N=20) and in minimally conscious (MCS; N=15) and vegetative states (VS; N=15) patients recorded at bedside. Whereas N400-like ERP components could be observed in the VS, MCS and conscious groups, only MCS and conscious groups showed a LPC response, suggesting that this late effect could be a potential specific marker of conscious semantic processing. This result is coherent with recent findings disentangling early and local non-conscious responses (e.g.: MMN in odd-ball paradigms, N400 in semantic violation paradigms) from late, distributed and conscious responses (e.g.: P3b to auditory rule violation) in controls and in patients with disorders of consciousness. However, N400 and LPC responses were not easily observed at the individual level, – even in conscious controls – , with standard ERP analyses, which is a limiting factor for its clinical use. Of potential interest, the only 3 patients presenting both significant N400 and LPC effects were MCS, and 2 of them regained consciousness and functional language abilities.
•The N400 correlate of semantic processing was found in groups of VS and MCS patients.•Only groups of MCS patients showed the LPC correlate of semantic processing.•N400 and LPC responses were not easily observed at the individual level.
Spinal cord stimulation (SCS) is a promising treatment for disorders of consciousness (DOC), but the underlying mechanism and most effective procedures remain uncertain. To optimize the protocol, ...previous studies evaluated the frequency-specific effects of SCS on neurophysiological activities. However, whether and how the inter-stimulus interval (ISI) parameter affects the SCS neuromodulation in DOC remains unknown. We enrolled nine DOC patients who had implanted SCS devices and conducted three different durations of ISIs. Using functional near-infrared spectroscopy (fNIRS), we monitored the blood volume fluctuations in the prefrontal and occipital cortices during the SCS. The results showed that short stimuli (30s) induced significant cerebral blood volume changes, especially in the prefrontal cortex, an important area in the consciousness system. By comparing the mean value of the responses from the first and the last block in each session, a shorter ISI was found to improve the blood volume in the prefrontal cortex. This phenomenon was more significant for the subgroup of patients with a favorable prognosis. These preliminary results imply that the ISI may be an important factor for SCS. The research paradigm proposed here also provides insights for further quantitative evaluations of the therapeutic effects of neuromodulation.
•Spinal cord stimulation rapidly evokes activity in consciousness-related brain areas.•Inter-stimulus interval of neuromodulation is important for treating disorders of consciousness.•Shorter inter-stimulus interval can better improve the blood volume in frontal area.•Near-infrared spectroscopy is feasible for evaluating neuromodulation effects.
Floatation-REST (Reduced Environmental Stimulation Therapy) minimizes stimulation of the nervous system by immersing subjects in an environment without sound or light while they effortlessly float in ...thermoneutral water supersaturated with Epsom salt. Here we investigated the relationship between altered states of consciousness (ASC) and its association with the affective changes induced by Floatation-REST. Using a within-subject crossover design, 50 healthy subjects were randomized to 60 min of Floatation-REST or 60 min of Bed-REST (an active control condition that entailed lying supine on a warm waterbed in a dark and quiet room). Following Floatation-REST, subjects felt significantly more relaxed, less anxious, and less tired than after Bed-REST. Floatation-REST also induced significantly more pronounced ASC characterized by the dissolution of body boundaries and the distortion of subjective time. The loss of body boundaries mediated the loss of anxiety, revealing a novel mechanism by which Floatation-REST exerts its anxiolytic effect.
This study aimed to empirically evaluate the hierarchical structure of the Coma Recovery Scale-Revised (CRS-R) rating scale categories and their alignment with the Aspen consensus criteria for ...determining disorders of consciousness (DoC) following a severe brain injury. CRS-R data from 262 patients with DoC following a severe brain injury were analyzed applying the partial credit Rasch Measurement Model. Rasch Analysis produced logit calibrations for each rating scale category. Twenty-eight of the 29 CRS-R rating scale categories were operationalized to the Aspen consensus criteria. We expected the hierarchical order of the calibrations to reflect Aspen consensus criteria. We also examined the association between the CRS-R Rasch person measures (indicative of performance ability) and states of consciousness as determined by the Aspen consensus criteria. Overall, the order of the 29 rating scale category calibrations reflected current literature regarding the continuum of neurobehavioral function: category 6 "Functional Object Use" of the Motor item was hardest for patients to achieve; category 0 "None" of the Oromotor/Verbal item was easiest to achieve. Of the 29 rating scale categories, six were not ordered as expected. Four rating scale categories reflecting the Vegetative State (VS)/Unresponsive Wakefulness Syndrome (UWS) had higher calibrations (reflecting greater neurobehavioral function) than the easiest Minimally Conscious State (MCS) item (category 2 "Fixation" of the Visual item). Two rating scale categories, one reflecting MCS and one not operationalized to the Aspen consensus criteria, had higher calibrations than the easiest eMCS item (category 2 "Functional: Accurate" of the Communication item). CRS-R person measures (indicating amount of neurobehavioral function) and states of consciousness, based on Aspen consensus criteria, showed a strong correlation (r
= 0.86;
< 0.01). Our study provides empirical evidence for revising the diagnostic criteria for MCS to also include category 2 "Localization to Sound" of the Auditory item and for Emerged from Minimally Conscious State (eMCS) to include category 4 "Consistent Movement to Command" of the Auditory item.
The intrinsic connectivity of the default mode network has been associated with the level of consciousness in patients with severe brain injury. Especially medial parietal regions are considered to ...be highly involved in impaired consciousness. To better understand what aspect of this intrinsic architecture is linked to consciousness, we applied spectral dynamic causal modeling to assess effective connectivity within the default mode network in patients with disorders of consciousness. We included 12 controls, 12 patients in minimally conscious state and 13 in vegetative state in this study. For each subject, we first defined the four key regions of the default mode network employing a subject-specific independent component analysis approach. The resulting regions were then included as nodes in a spectral dynamic causal modeling analysis in order to assess how the causal interactions across these regions as well as the characteristics of neuronal fluctuations change with the level of consciousness. The resulting pattern of interaction in controls identified the posterior cingulate cortex as the main driven hub with positive afferent but negative efferent connections. In patients, this pattern appears to be disrupted. Moreover, the vegetative state patients exhibit significantly reduced self-inhibition and increased oscillations in the posterior cingulate cortex compared to minimally conscious state and controls. Finally, the degree of self-inhibition and strength of oscillation in this region is correlated with the level of consciousness. These findings indicate that the equilibrium between excitatory connectivity towards posterior cingulate cortex and its feedback projections is a key aspect of the relationship between alterations in consciousness after severe brain injury and the intrinsic functional architecture of the default mode network. This impairment might be principally due to the disruption of the mechanisms underlying self-inhibition and neuronal oscillations in the posterior cingulate cortex.
In the 1970s, memory researchers converged on interesting phenomena observed in Korsakoff-syndrome amnesic patients. These patients' performances on difficult tasks were reliably improved by practice ...sessions from which they could recall nothing. Related findings of indirect memory effects in college students triggered wide attention to phenomena that, in 1985, were first identified as implicit memory. Within a decade, the indirect measurement methods of implicit memory research had spread to social psychologists' studies of attitudes and stereotypes. After another two decades, the methods and findings of this developing revolution have revised understanding of how past learning, operating in ways that bypass conscious awareness, nevertheless shapes conscious judgment and perception. This revolution in psychological thinking is on the cusp of reconceiving the relation between unconscious and conscious mental process. Further, it demands researchers' careful attention to justification for many self-report measures that are now routinely treated as face-valid.
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CEKLJ, FFLJ, NUK, ODKLJ, PEFLJ
The diagnosis and prognosis of patients with severe chronic disorders of consciousness are still challenging issues and a high rate of misdiagnosis is evident. Hence, new tools are needed for an ...accurate diagnosis, which will also have an impact on the prognosis. In recent years, functional Magnetic Resonance Imaging (fMRI) has been gaining more and more importance when diagnosing this patient group. Especially resting state scans, i.e., an examination when the patient does not perform any task in particular, seems to be promising for these patient groups. After preprocessing the resting state fMRI data with a standard pipeline, we extracted the correlation matrices of 132 regions of interest. The aim was to find the regions of interest which contributed most to the distinction between the different patient groups and healthy controls. We performed feature selection using a genetic algorithm and a support vector machine. Moreover, we show by using only those regions of interest for classification that are most often selected by our algorithm, we get a much better performance of the classifier.
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