Geneeskundige Stichting Koningin Elisabeth ... - GSKE - FMRE

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• Reactivation during REM sleep of cerebral areas involved in an serial reaction time (SRT) task,
P. Maquet, C. Petiau, P. Peigneux, C. Phillips, S. Laureys, C. Smith, A. Cleeremans, A. Luxen,
G. Franck, M. Van der Linden,
Neuroimage, 9 (1999), S981.
Study of patients with altered states of consciousness
This project was run by Steven Laureys and Pierre Maquet, in collaboration with 2
Anaesthesiologists (Dr Marie-Elisabeth Faymonville and Dr. Nathalie Janssens). This is a prospective
study of cerebral glucose metabolism at rest and cerebral blood flow at rest and under
auditory or somato-sensory stimulation in vegetative state patients.
Vegetative state is characterised by preserved arousal but abolished awareness of self and
environment. Our results confirm that, in vegetative patients, the cerebral glucose metabolism
is decreased by 40 to 60 % as compared to normal subjects. We were the first to map brain
areas that are systematically most impaired in VS. These areas were localised in polymodal
associative cortices (bilateral prefrontal regions, Broca’s area, parieto-temporal and posterior
parietal areas and precuneus) (published in NeuroImage and cover of Physiological Imaging of
the Brain using PET) and were shown to be functionally disconnected from both thalami (presumed
intralaminar nuclei) (Book Chapter in Physiological Imaging of the Brain using PET).
Interestingly, recovery of awareness of self and environment was paralleled by a functional
recovery of metabolism in these same cortical regions (results published in Lancet as a
Correspondence Letter). Moreover, we were able to show that the altered cortico-thalamo-cortical
modulation in vegetative state, regained near normal values after recovery of awareness
(results published in Lancet as a Research Letter).
We than showed that external (auditory or noxious somatosensory) stimulation is still able
to activate the primary cortices but not the associative cortices. Furthermore, in vegetative
patients, functional connectivity is impaired along the usual processing streams of these inputs.
The data concerning auditory stimulation are now published in Brain. A manuscript is in preparation
for the somato-sensory data. It sheds light on the clinically very relevant issue of pain
perception and suffering in patients in the vegetative state. In summary, even though the
patients’ metabolism of the brain was much lower than normal (less than half of normal values),
some regions still showed significant activation during noxious stimulation: the brainstem, the
thalamus and the primary somatosensory cortex. However, a large network of hierarchically
‘higher-order’ multi-modal association areas failed to activate: the secondary somatosensory
cortices, the insular regions, the posterior parietal and prefrontal areas and the anterior cingulate
cortex (regions that are known to be involved in pain affect, attention and memory).
Moreover, primary somatosensory cortex, the only cortical region that activated in vegetative
patients, was no longer functionally connected with the rest of the brain (i.e., the ‘higher order’
brain regions thought to be necessary for conscious processing) ( see fig. 2). Our results show
that severely depressed brain regions in patients in a vegetative state can be activated by peripheral
noxious stimuli. This activation, however, remains limited to subcortical and primary cortical
regions. As the observed cortical activation is isolated and functionally disconnected it can-