Detecting the Potential for Consciousness in Unresponsive Patients Using the Perturbational Complexity Index.

The difficulties of behavioral evaluation of prolonged disorders of consciousness (DOC) motivate the development of brain-based diagnostic approaches. The perturbational complexity index (PCI), which measures the complexity of electroencephalographic (EEG) responses to transcranial magnetic stimulation (TMS), showed a remarkable sensitivity in detecting minimal signs of consciousness in previous studies. Here, we tested the reliability of PCI in an independently collected sample of 24 severely brain-injured patients, including 11 unresponsive wakefulness syndrome (UWS), 12 minimally conscious state (MCS) patients, and 1 emergence from MCS patient. We found that the individual maximum PCI value across stimulation sites fell within the consciousness range (i.e., was higher than PCI*, which is an empirical cutoff previously validated on a benchmark population) in 11 MCS patients, yielding a sensitivity of 92% that surpassed qualitative evaluation of resting EEG. Most UWS patients (n = 7, 64%) showed a slow and stereotypical TMS-EEG response, associated with low-complexity PCI values (i.e., ≤PCI*). Four UWS patients (36%) provided high-complexity PCI values, which might suggest a covert capacity for consciousness. In conclusion, this study successfully replicated the performance of PCI in discriminating between UWS and MCS patients, further motivating the application of TMS-EEG in the workflow of DOC evaluation.

The ability to understand emotions is associated with interoception-related insular activation and white matter integrity during aging.

Cerebral small vessel disease (SVD) is a major cause of cognitive impairment in elderly people. While most research focuses on the role of the classical vascular risk factors in SVD, a description of the psychophysiological mechanisms leading to the age-related brain damage may open new possibilities for prophylaxis. In the current study, we evaluated the associations between emotional abilities, interoception, and age-related vascular white matter degeneration. The work was influenced, first, by multiple studies recognizing alexithymia as a cardiovascular risk factor; second, by theories of emotions linking body's allostasis and emotional regulation; and third, by neuroimaging data highlighting the shared role of the insular cortex in interoceptive and emotional processing. In a sample of older female adults (N = 30), we performed the Mayer-Salovey-Caruso Emotional Intelligence Test, functional MRI using the heartbeat detection task, and evaluation of white matter microstructural integrity using diffusion weighted imaging. The ability to understand and analyze emotions-one of the four components of emotional intelligence-was found to be associated with higher interoception-related activation of the right anterior insula and preserved white matter microstructure. We interpret these results in light of the concept of Embodied Predictive Interoception Coding, which proposes that emotional processing, interoception, and allostasis (antecedent top-down regulation of the body's internal milieu) may rely on the shared neural mechanisms of predictive coding. The study demonstrates feasibility of the investigation of cerebrovascular diseases form a psychophysiological perspective and calls for future research.