Abstract
One challenging aspect of the clinical assessment of brain-injured, unresponsive patients is the lack of an objective measure of consciousness that is independent of the subject's ability to interact with the external environment. Theoretical considerations suggest that consciousness depends on the brain's ability to support complex activity patterns that are, at once, distributed among interacting cortical areas (integrated) and differentiated in space and time (information-rich). We introduce and test a theory-driven index of the level of consciousness called the perturbational complexity index (PCI). PCI is calculated by (i) perturbing the cortex with transcranial magnetic stimulation (TMS) to engage distributed interactions in the brain (integration) and (ii) compressing the spatiotemporal pattern of these electrocortical responses to measure their algorithmic complexity (information). We test PCI on a large data set of TMS-evoked potentials recorded in healthy subjects during wakefulness, dreaming, nonrapid eye movement sleep, and different levels of sedation induced by anesthetic agents (midazolam, xenon, and propofol), as well as in patients who had emerged from coma (vegetative state, minimally conscious state, and locked-in syndrome). PCI reliably discriminated the level of consciousness in single individuals during wakefulness, sleep, and anesthesia, as well as in patients who had emerged from coma and recovered a minimal level of consciousness. PCI can potentially be used for objective determination of the level of consciousness at the bedside.
| Original language | English |
|---|---|
| Article number | 198ra105 |
| Journal | Science Translational Medicine |
| Volume | 5 |
| Issue number | 198 |
| DOIs | |
| Publication status | Published - Aug 14 2013 |
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ASJC Scopus subject areas
- Medicine(all)
Cite this
A theoretically based index of consciousness independent of sensory processing and behavior. / Casali, Adenauer G.; Gosseries, Olivia; Rosanova, Mario; Boly, Mélanie; Sarasso, Simone; Casali, Karina R.; Casarotto, Silvia; Bruno, Marie Aurélie; Laureys, Steven; Tononi, Giulio; Massimini, Marcello.
In: Science Translational Medicine, Vol. 5, No. 198, 198ra105, 14.08.2013.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A theoretically based index of consciousness independent of sensory processing and behavior
AU - Casali, Adenauer G.
AU - Gosseries, Olivia
AU - Rosanova, Mario
AU - Boly, Mélanie
AU - Sarasso, Simone
AU - Casali, Karina R.
AU - Casarotto, Silvia
AU - Bruno, Marie Aurélie
AU - Laureys, Steven
AU - Tononi, Giulio
AU - Massimini, Marcello
PY - 2013/8/14
Y1 - 2013/8/14
N2 - One challenging aspect of the clinical assessment of brain-injured, unresponsive patients is the lack of an objective measure of consciousness that is independent of the subject's ability to interact with the external environment. Theoretical considerations suggest that consciousness depends on the brain's ability to support complex activity patterns that are, at once, distributed among interacting cortical areas (integrated) and differentiated in space and time (information-rich). We introduce and test a theory-driven index of the level of consciousness called the perturbational complexity index (PCI). PCI is calculated by (i) perturbing the cortex with transcranial magnetic stimulation (TMS) to engage distributed interactions in the brain (integration) and (ii) compressing the spatiotemporal pattern of these electrocortical responses to measure their algorithmic complexity (information). We test PCI on a large data set of TMS-evoked potentials recorded in healthy subjects during wakefulness, dreaming, nonrapid eye movement sleep, and different levels of sedation induced by anesthetic agents (midazolam, xenon, and propofol), as well as in patients who had emerged from coma (vegetative state, minimally conscious state, and locked-in syndrome). PCI reliably discriminated the level of consciousness in single individuals during wakefulness, sleep, and anesthesia, as well as in patients who had emerged from coma and recovered a minimal level of consciousness. PCI can potentially be used for objective determination of the level of consciousness at the bedside.
AB - One challenging aspect of the clinical assessment of brain-injured, unresponsive patients is the lack of an objective measure of consciousness that is independent of the subject's ability to interact with the external environment. Theoretical considerations suggest that consciousness depends on the brain's ability to support complex activity patterns that are, at once, distributed among interacting cortical areas (integrated) and differentiated in space and time (information-rich). We introduce and test a theory-driven index of the level of consciousness called the perturbational complexity index (PCI). PCI is calculated by (i) perturbing the cortex with transcranial magnetic stimulation (TMS) to engage distributed interactions in the brain (integration) and (ii) compressing the spatiotemporal pattern of these electrocortical responses to measure their algorithmic complexity (information). We test PCI on a large data set of TMS-evoked potentials recorded in healthy subjects during wakefulness, dreaming, nonrapid eye movement sleep, and different levels of sedation induced by anesthetic agents (midazolam, xenon, and propofol), as well as in patients who had emerged from coma (vegetative state, minimally conscious state, and locked-in syndrome). PCI reliably discriminated the level of consciousness in single individuals during wakefulness, sleep, and anesthesia, as well as in patients who had emerged from coma and recovered a minimal level of consciousness. PCI can potentially be used for objective determination of the level of consciousness at the bedside.
UR - http://www.scopus.com/inward/record.url?scp=84883894654&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84883894654&partnerID=8YFLogxK
U2 - 10.1126/scitranslmed.3006294
DO - 10.1126/scitranslmed.3006294
M3 - Article
C2 - 23946194
AN - SCOPUS:84883894654
VL - 5
JO - Science Translational Medicine
JF - Science Translational Medicine
SN - 1946-6234
IS - 198
M1 - 198ra105
ER -