Dynamic Patterns of Global Brain Communication Differentiate Conscious From Unconscious Patients After Severe Brain Injury

Abstract

The neurophysiology of the subjective sensation of being conscious is elusive; therefore, it remains controversial how consciousness can be recognized in patients who are not responsive but seemingly awake. During general anesthesia, a model for the transition between consciousness and unconsciousness, specific covariance matrices between the activity of brain regions that we call patterns of global brain communication reliably disappear when people lose consciousness. This functional magnetic imaging study investigates how patterns of global brain communication relate to consciousness and unconsciousness in a heterogeneous sample during general anesthesia and after brain injury. First, we describe specific patterns of global brain communication during wakefulness that disappear during propofol (n = 11) and sevoflurane (n = 14) general anesthesia. Second, we search for these patterns in a cohort of unresponsive wakeful patients (n = 18) and unmatched healthy controls (n = 20) in order to evaluate their potential use in clinical practice. We found that patterns of global brain communication characterized by high covariance in sensory and motor areas or low overall covariance and their dynamic change were strictly associated with intact consciousness in this cohort. In addition, we show that the occurrence of these two patterns is significantly related to activity within the frontoparietal network of the brain, a network known to play a crucial role in conscious perception. We propose that this approach potentially recognizes consciousness in the clinical routine setting.

What lies underneath: Precise classification of brain states using time-dependent topological structure of dynamics

“…This has been a practical solution since individual matrices were not provided for all participants. For patients with severe brain injury the classification would possibly improve if these injuries were reflected in connectivity, since alterations within specific brain networks impairs communication among networks [53]. As we observed above, the influence of the SC matrix on LV equations is always multiplied by the activity of the respective networks.…”

Brain areas modulation in consciousness during sevoflurane anesthesia

“…The connectivity and integration across the frontal and parietal cortices have a crucial relationship to both LOC and ROC, whereby the connectivity between these two brain regions is regarded as the foundation for conscious changes during anesthesia (Alkire et al, 2008 ), including sevoflurane-induced unconsciousness. Comparisons of functional magnetic resonance images between patients anesthetized with sevoflurane and those presenting with brain injury showed that a discrepancy between the sensory and motor areas, their overall similarity, and dynamic change were closely associated with complete consciousness linked to the activity of the fronto-parietal network (Golkowski et al, 2021 ). In fact, the whole prefrontal cortex seems to have a significant correlation with consciousness, including the dorsomedial, dorsolateral and ventromedial prefrontal cortices, as measured by fisher scores by using vector machines.…”

Disruption in structural–functional network repertoire and time-resolved subcortical fronto-temporoparietal connectivity in disorders of consciousness

“…The analysis of dynamic or time-resolved functional connectivity, as well as the relationship between the underlying anatomical connections and emergent time-resolved functional connectivity ( Avena-Koenigsberger et al, 2018 ; Suárez et al, 2020 ), may be clinically relevant in patients with DoC. Previous studies have already explored the role of time-resolved functional connectivity in DoC ( Del Pozo et al, 2021 ; Golkowski et al, 2021 ; Sanz Perl et al, 2021 ). A recent study demonstrated that network states with long-distance connections occurred less frequently over time in MCS compared to UWS patients ( Demertzi et al, 2019 ), emphasizing disintegration of interactions across the cortex in unconscious states.…”