Casali Processing and Behavior A Theoretically Based Index of Consciousness Independent of Sensory

a prerequisite for deployment in the clinic. robust measure that distinguishes conscious from unconscious states well enough to be used on an individual basis, appears to be a et al. of being derived from a simple noninvasive measurement. The new index reported by Casali The validity of PCI for clinical application will need to be assessed in prospective trials, but it has the advantage conscious state showing intermediate values (0.32 to 0.49). unconscious (0.19 to 0.31), the two with locked-in syndrome clearly aware (0.51 to 0.62), and those in a minimally patients clearly reflected the state of their consciousness, with the six patients in a vegetative state clearly in a vegetative state or minimally conscious state, or exhibited locked-in syndrome. The PCI values from these from stroke or trauma. Here, too, the authors found promising results in those who had emerged from coma but were conventional assessment methods? In these people, consciousness varies widely, as does the underlying damage However, what about patients who suffer brain damage and who exhibit various levels of consciousness by 0.31. ''unconscious'' values for the PCI: midazolam deep sedation, 0.23 to 0.31; propofol, 0.13 to 0.30; and xenon, 0.12 to patients given various amounts of the anesthetics midazolam, xenon, and propofol. These agents too caused low completely different way of inducing unconsciousness had the same effect on PCI, the authors assessed data from awake healthy people, but fell to 0.18 to 0.28 during nonrapid eye movement (NREM) sleep. Then, to see whether a comparing the unique information in each, the authors derived PCI values. The values ranged from 0.44 to 0.67 in 32 brains with transcranial magnetic stimulation. By calculating the likely brain regional sources of the signals and then The authors used data already collected from previous experiments, in which they had stimulated people's brain's response to a magnetic stimulus. The PCI could allow tracking of consciousness in individual patients. index of human consciousness [the perturbational complexity index (PCI)] that reflects the information content of the extended their previous work on electrical correlates of consciousness to define an electroencephalographic-derived have et al. have locked-in syndrome (in which they are aware but cannot respond) are unconscious. Here, Casali provide reliable reactions, and a more precise index is needed to avoid, for example, the conclusion that people who crudest of tools to detect when a person is not aware. The usual question or physical stimulus does not always but physicians have only the −− think anesthesia −− Manipulation of consciousness is an everyday medical trick Quantifying the Unquantifiable