An article describing it here;
Brain Shaking Technique - strong magnetic stimulation - Offers Measure of Consciousness
The abstract here;
http://stm.sciencemag.org/content/5/198/198ra105
- Adenauer G. Casali1,*,†,
- Olivia Gosseries2,*,
- Mario Rosanova1,
- Mélanie Boly2,‡,
- Simone Sarasso1,
- Karina R. Casali1,3,
- Silvia Casarotto1,
- Marie-Aurélie Bruno2,
- Steven Laureys2,
- Giulio Tononi4 and
- Marcello Massimini1,5,§
+ Author Affiliations
- ↵§Corresponding author. E-mail: marcello.massimini@unimi.it
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.
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