Casali et
al. [2013] have shown that the patterns of electroencephalography (EEG) induced
by a cortical transcranial magnetic stimulation (TMS) pulse are different for
conscious and unconscious subjects. While in conscious subjects the
spatio-temporal patterns of activation are complex, in asleep, anesthesized or
vegetative state individuals, the TMS induces just a short undifferentiated
response. The results still need to be evaluated taking bigger samples but the
approach is interesting and could be of great help for the diagnosis of
vegetative state patients and the monitoring of anesthesia. On the other hand the
results are consistent with theories that associate consciousness with a
preserved functional thalamocortical system which communicates local activation
to many distant cortical sites entertaining long-lasting reverberating states [Sitt
et al. 2013].
References
Casali,
A.G. et al. [2013] A
theoretically based index of consciousness independent of sensory processing
and behavior. Sci.
Transl. Med. 5, 198ra105.
Sitt,
Jacobo D.; King, Jean-Rémi; Naccache, Lionel and Dehaene, Stanislas. [2013] Ripples of consciousness. Trends in
Cognitive Sciences. November 2013, Vol. 17, No. 11.
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