Abstract
Recent advances in neuroimaging have demonstrated that patients with disorders of consciousness (DOC) may retain residual consciousness through activation of a complex functional brain network. However, an understanding of the hierarchy of residual consciousness and dynamic network connectivity in DOC patients is lacking. This study aimed to investigate residual consciousness and the dynamics of neural processing in DOC patients. We included 42 patients with DOC, categorized by aetiology. Event-related potentials combined with time-varying electroencephalography networks were used to probe affective consciousness in DOC and examine the related network mechanisms. The results showed an obvious frontal P3a component among patients in minimally conscious state (MCS), while a prominent N1 was observed in unresponsive wakefulness syndrome (UWS). No late positive potential (LPP) was detected in these patients. Next, we divided the results by aetiology. Patients with nontraumatic injury presented an obvious frontal P3a response compared to those with traumatic injury. With respect to the dynamic network mechanism, patients with UWS, both with and without trauma, exhibited impaired frontoparietal network connectivity during the middle to late emotion processing period (P3a and LPP). Surprisingly, unconscious post-traumatic patients had an evident deficit in top-down connectivity. This, it appears that early automatic sensory identification is preserved in UWS and that exogenous attention was preserved even in MCS. However, high-level cognitive abilities were severely attenuated in unconscious patients. We also speculate that reduced frontoparietal connectivity may be useful as a biomarker to distinguish patients in an MCS from those with UWS given the same aetiology.
Highlights
Recent advances in neuroimaging have demonstrated that patients with disorders of consciousness (DOC) may retain residual consciousness through activation of a complex functional brain network
Investigations have reported that disrupted default mode network (DMN) activity is related to loss of consciousness, and Demertzi further reported on auditory network differences between minimally conscious state (MCS) and unresponsive wakefulness syndrome (UWS) patients [911]
In the UWS groups, none of the middle to late ERP components (P3a and late positive potential (LPP)) significantly differed between the neutral and emotional settings, whereas the amplitude of N1 was increased during emotion processing (Fig. 2B)
Summary
Recent advances in neuroimaging have demonstrated that patients with disorders of consciousness (DOC) may retain residual consciousness through activation of a complex functional brain network. Recent research has shown that brain functional connectivity is not static but rather exhibits spontaneous fluctuations over time [12, 13] These fluctuating network connections, especially the dynamic time-varying connections in various stages of emotional sound processing, are unclear, and understanding this dynamic network mechanism may help elucidate the impairment of information processing in DOC [14]. We applied the ADTF methodology to assess DOC patients’ underlying pathological states of consciousness with the aim of obtaining spatiotemporal network information. This information may be valuable for improved understanding of the different dysfunctional connectivity patterns in UWS and MCS patients. We examined a large sample of patients with traumatic and nontraumatic DOC to ascertain the relevance of aetiology and network connectivity and to determine the mechanism of individuals’ brain injuries
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
