Summary: A study of people with unresponsive panic disorder, formerly known as the “vegetable state,” and low levels of consciousness shows altered brain activity.
Source: University of Liège
A study by the Human Brain Project (HBP), led by scientists at the University of Liège (Belgium), investigated new techniques to distinguish between two different neurological conditions in patients with severe brain injury and/or coma. The results of this study were published in the open access journal eLife.
One of the greatest challenges in neurology and critical care medicine is to accurately assess the level of consciousness of a patient in a coma due to severe brain injury.
Scientists in the Human Brain Project (HBP) – an international project involving more than 500 researchers, using a unique interdisciplinary approach at the interface of neuroscience and technology, aims to deeply understand the complex structure and function of the human brain – exploring new methods to distinguish two different neurological conditions.
The results of this new study, just published in the journal eLife, describe important information about the mechanisms of consciousness disorders. Between a group of researchers from the University of Liège (GIGA Department of Consciousness Studies, Coma Science Group, Faculty of Medicine) and the Hospital of the University of Liège (Belgium), the Université Pompeu Fabra (Spain), the Vrije Universiteit Amsterdam (Netherlands). Others, have evaluated functional brain networks as a marker of consciousness to differentiate between patients with unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS).
“Previously called ‘vegetative state’, the unresponsive Arasial syndrome is a patient who wakes up from a coma, that is, he opens his eyes but does not respond to the environment and verbal commands, showing only reflexes,” he explains. Rajinikanth Panda, first author of the paper and researcher at the GIGA Consciousness and Coma Science Group at ULiège.
“In contrast, patients in a minimally conscious state show minimal signs of awareness, such as following eye movements or lifting a finger when prompted.”
The differentiation of these states is important for the correct diagnosis, prognosis and rehabilitation treatment, and is related to important quality of life and even end-of-life decisions.
The study included 34 healthy controls, 30 minimally conscious patients, and 14 non-responsive conscious patients. These patients were sent from all over Europe to the Coma Science Group – led by neurologist Steven Laures – and the University Hospital of Liège for a second opinion.
Data sharing and analysis benefited from HBP’s EBRAINS infrastructure and the collaboration of research groups led by Jitka Anen (Coma Science Group/ULiège Faculty of Medicine) and Prejas Tewari (Vrije Universiteit Amsterdam).
We used state-of-the-art techniques to assess different brain structures and their relationship to network dynamics,” said Jitka Anen. “We showed that these techniques are sensitive enough to identify clinically relevant differences in the diagnosis of small patients. State of consciousness and unresponsive wakefulness syndrome.
Specifically, the researchers used functional magnetic resonance imaging (fMRI) data to analyze dynamic functional connectivity, or how brain regions connect to each other, connections between neural populations, and structural white matter connections.
“Compared to the low state of consciousness, we showed that patients with unresponsive consciousness showed less activity in functional networks, reduced heart rate variability (a state of stable functional connectivity different from the natural steady state) and coupling of functional connectivity to a structural framework,” says GIGA Consciousness and Aurore Thibaut, FNRS researcher at the Coma Science Group, explains.
“This new approach also revealed a brain network that separates conscious and unconscious states – a network that includes subcortical regions and frontotemporoparietal cortical areas.”
These findings support previous ideas about the mechanisms involved in the loss and recovery of consciousness, such as the global neural workspace theory and the mesocircuit hypothesis, which suggest that failure to regain consciousness is related to a loss of connectivity between subcortical and frontoparietal brain areas. As well as losing the range of functional network states.
“The study, which was partially funded by the HBP, the Belgian National Fund for Scientific Research (FNRS) and the Generet Prize of the King Baudouin Foundation, is a good example of how current theories of consciousness can and should be challenged by real clinical neuroimaging data. Patient care translates,” concluded Jitka Anen, the paper’s senior author and a scientist at Giga’s Consciousness Research Unit.
So neuro research news
Preliminary study: Open Access.
“Structural-functional network performance and time-resolved subcortical fronto-temporal disconnection in cognitive impairment.” by Rajnikant Panda et al. eLife
Structural-functional network performance and time-resolved subcortical fronto-temporal disconnection in cognitive impairment.
Understanding the recovery of consciousness and elucidating its underlying mechanisms is believed to be critical in the fields of basic neuroscience and medicine. Ideas such as the Global Neuronal Workspace (GNW) and the Mesocircuit Theory suggest that the failure to recover in conscious states is consistent with the loss of connectivity between subcortical and frontoparietal areas, loss of performance of functional networks states, and metastable brain activity.
To explore these ideas, we adopted a time-resolved functional connectivity framework and evaluated the performance of functional network states as a marker of consciousness and its ability to distinguish patients with unresponsive wakefulness syndrome (UWS) and minimally conscious wakefulness syndrome (MCS). . In addition, these functional network projections are augmented as potential markers by locating hidden spatial patterns in the anatomical network, called eigenmodes.
By analyzing time-resolved functional connectivity from functional MRI data, we demonstrated a reduction in metastasizing and functional network repertoire in UWS compared with MCS patients. This was explained by reduced dwell time and destabilization of the default mode network and the subcortical fronto-temporoparietal network in UWS compared to MCS patients.
We also show that these findings are accompanied by a loss of dynamic interaction between structural eigenmodes and time-resolved functional connectivity in the UWS.
These results support the role of time-resolved thalamo-cortical connections and recovery of consciousness, among others, in support of the GNW theory and the mesocircuit hypothesis.