Recovery of cortical effective connectivity and recovery of consciousness in vegetative patients

By V. Verdon, Sophie Schwartz, K. Lovblad, Claude-Alain Hauert, Patrik Vuilleumier. Brain : a journal of neurology, 2012

951 citations recorded by the source corpus.

Patients surviving severe brain injury may regain consciousness without recovering their ability to understand, move and communicate. Recently, electrophysiological and neuroimaging approaches, employing simple sensory stimulations or verbal commands, have proven useful in detecting higher order processing and, in some cases, in establishing some degree of communication in brain-injured subjects with severe impairment of motor function. To complement these approaches, it would be useful to develop methods to detect recovery of consciousness in ways that do not depend on the integrity of sensory pathways or on the subject's ability to comprehend or carry out instructions. As suggested by theoretical and experimental work, a key requirement for consciousness is that multiple, specialized cortical areas can engage in rapid causal interactions (effective connectivity). Here, we employ transcranial magnetic stimulation together with high-density electroencephalography to evaluate effective connectivity at the bedside of severely brain injured, non-communicating subjects. In patients in a vegetative state, who were open-eyed, behaviourally awake but unresponsive, transcranial magnetic stimulation triggered a simple, local response indicating a breakdown of effective connectivity, similar to the one previously observed in unconscious sleeping or anaesthetized subjects. In contrast, in minimally conscious patients, who showed fluctuating signs of non-reflexive behaviour, transcranial magnetic stimulation invariably triggered complex activations that sequentially involved distant cortical areas ipsi- and contralateral to the site of stimulation, similar to activations we recorded in locked-in, conscious patients. Longitudinal measurements performed in patients who gradually recovered consciousness revealed that this clear-cut change in effective connectivity could occur at an early stage, before reliable communication was established with the subject and before the spontaneous electroencephalogram showed significant modifications. Measurements of effective connectivity by means of transcranial magnetic stimulation combined with electroencephalography can be performed at the bedside while by-passing subcortical afferent and efferent pathways, and without requiring active participation of subjects or language comprehension; hence, they offer an effective way to detect and track recovery of consciousness in brain-injured patients who are unable to exchange information with the external environment.

Subfields: Cognitive Neuroscience, Epidemiology

View Paper: https://www.semanticscholar.org/paper/0f61938e951d972e414e1bd298219e2bd659f88a

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In Cognitive Neuroscience

Citations in the corpus

Why use a connectivity-based approach to study stroke and recovery of function? (2012, neutral): “, 2007), attention (Committeri et al., 2007; Molenberghs et al., 2008; Verdon et al., 2010), motor planning (Kalenine et al.”
Global Workspace Dynamics: Cortical “Binding and Propagation” Enables Conscious Contents (2013, positive): “It has been shown to differentiate between conscious waking vs. sleep and coma, and to distinguish behavioral coma from true coma (Rosanova et al., 2012). www.frontiersin.org May 2013 | Volume 4 | Article 200 | 3 FIGURE 1 | Binding and broadcasting from many locations.”
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A new neural framework for visuospatial processing (2011, background): “In humans, egocentric hemi-spatial neglect most commonly arises from damage to the IPL 63–65 , whereas allocentric neglect (that is, hemi-spatial neglect relative to objects) is primarily associated with damage to ventral cortical areas, including the MTL 63,64 .”
The non-transcranial TMS-evoked potential is an inherent source of ambiguity in TMS-EEG studies (2018, positive): “The determination of the exact coil position was based on individual anatomical MRIs as described previously (Rosanova et al., 2012).”
Distinct Spectral Profiles of Awake Resting EEG in Disorders of Consciousness: The Role of Frequency and Topography of Oscillations (2022, unknown): “We adopted the total CRS-R score (range 2–23 with the mean of 10.714 ± 5.941), as the index of the overall level of neurocognitive capacity in PDOC patients (Bodart et al. 2018; Rosanova et al. 2012).”