Comput. Methods Programs Biomed.
July 1, 2019
J. R. D. Miras, F. Soler‐Toscano, S. Iglesias-Parro et al.
A measure combining fractal dimensions of brain activity—capturing both integration and differentiation of cortical responses—can distinguish conscious from unconscious states almost perfectly within individuals. In 18 healthy subjects, the Fractal Dimension Index (FDI) derived from high-density EEG after transcranial magnetic stimulation was significantly lower during non-REM sleep and sedation (with xenon or propofol) than during wakefulness. The index reflects how complex and differentiated the brain's spatiotemporal responses are to a perturbation. The findings suggest that tracking fractal dimensions of cortical dynamics offers a way to assess consciousness, with potential clinical applications for detecting awareness in patients.
Nature Human Behaviour
February 1, 2019
M. Michel, Diane M Beck, N. Block et al.
Advancing scientific research on consciousness is important for addressing clinical and ethical issues in neurology and mental health. To support this field, funding priorities must be set carefully, and challenges such as job creation and media misrepresentation need to be addressed.
Frontiers in Neurology
August 28, 2018
Audrey Vanhaudenhuyse, Vanessa Charland-Verville, Aurore Thibaut et al.
A patient diagnosed with unresponsive wakefulness syndrome/vegetative state for 20 years was found to be fully conscious and able to communicate functionally after repeated standardized behavioral exams and neuroimaging (MRI and PET). The diagnosis was revised to incomplete locked-in syndrome, with the main lesion in the brainstem. The authors propose that clinical evaluations of severely brain-damaged patients with motor impairment should routinely include repeated behavioral assessments and neuroimaging.
Psychological Research
July 1, 2018
Charlotte Martial, Vanessa Charland-Verville, Hedwige Dehon et al.
People who have had a near-death experience (NDE) are no more likely than others to form false memories, but when they do, they recall those false memories with a stronger sense of vivid, compelling recollection. The study used a standard word-list task to test memory in 20 individuals who had an NDE during a life-threatening event and 20 matched controls who had a life-threatening event without an NDE. Both groups produced false memories at similar rates, but those with NDEs more often reported that the false items felt like real, detailed memories. Further analysis indicated that both groups thought of the false items equally often, but the NDE group was less able to correctly monitor the source of those thoughts.
Frontiers in Human Neuroscience
January 1, 2017
Charlotte Martial, Héléna Cassol, Georgios Antonopoulos et al.
correction
This is a correction notice for a previously published article. It specifies that an error on page 311 in volume 11, identified by PMID 28659779, has been corrected. The notice provides no new findings, arguments, or data.
arXiv Preprint Archive
May 10, 2016
Enrico Amico, Daniele Marinazzo, Carol DiPerri et al.
A new data-driven method, connICA, extracts independent functional connectivity patterns (FC-traits) from brain scans of patients with disorders of consciousness after severe brain damage. Three main FC-traits emerged. The first relates to sedation, overall pathology, and level of arousal. The second reflects disconnection of visual and sensory-motor networks, time since injury, and ability to communicate. The third involves fronto-parietal and default-mode networks and interhemispheric interaction, associated with self-awareness and awareness of surroundings. Each trait represents a distinct functional process linked to degradation of conscious states, clarifying which neural subcircuits are disrupted in severe brain injury.
Consciousness and Cognition
July 1, 2015
Vanessa Charland-Verville, Zulay Lugo, Jean-Pierre Jourdan et al.
Memories of near-death experiences (NDEs) are usually emotionally positive, but this study compared NDEs in 8 patients with locked-in syndrome (LIS) from acute brainstem lesions to 23 classical NDE experiencers after coma with supratentorial lesions. LIS NDEs less frequently included feelings of peacefulness or well-being. The findings suggest that NDEs with less positive emotions may stem from impaired pontine/paralimbic connectivity or from the emotional distress of being conscious while paralyzed.
Neuroimage
May 15, 2011
Christophe L Phillips, Marie-Aurélie Bruno, Pierre Maquet et al.
A machine-learning classifier trained on fluorodeoxyglucose PET brain scans from 37 healthy controls and 13 patients in a vegetative state achieved 100% accuracy in distinguishing between conscious awareness and the vegetative state during cross-validation. When tested on 8 patients with locked-in syndrome, all scans were classified as "conscious" with a mean probability of .95. The authors conclude that relevance vector machine classification of cerebral metabolic images could become a useful tool for automated PET-based diagnosis of altered states of consciousness in coma survivors.
Trends in Cognitive Sciences
June 1, 2005
B. Baars, Steven Laureys
The authors critique Ned Block's distinction between phenomenological consciousness (what we experience) and access consciousness (information accessible via conscious experiences). They argue that evidence from cognitive neuroscience does not support this division. For instance, visual cortex activity is necessary but not sufficient for conscious visual qualities; without parietal and prefrontal activation, no correlation with consciousness is found. Similarly, when frontoparietal regions are impaired, sensory consciousness is absent despite sensory cortex activation. The authors contend that unconscious brain mechanisms interact with visual cortex to enable visual qualities, and that positing a separate 'access consciousness' is unnecessary. They suggest that what is needed is simply consciously-mediated access to brain capacities, most of which are unconscious.