Article (Scientific journals)
Reaching across the abyss: recent advances in functional magnetic resonance imaging and their potential relevance to disorders of consciousness
Soddu, Andrea; Boly, Mélanie; Nir, Yval et al.
2009In Progress in Brain Research, 177, p. 261-274
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Keywords :
Coma; consciousness; resting state; spontaneous activity; resonance imaging; default network
Abstract :
[en] Disorders of consciousness (DOC) raise profound scientific, clinical, ethical, and philosophical issues. Growing knowledge on fundamental principles of brain organization in healthy individuals offers new opportunities for a better understanding of residual brain function in DOCs. We here discuss new perspectives derived from a recently proposed scheme of brain organization underlying consciousness in healthy individuals. In this scheme, thalamo-cortical networks can be divided into two, often antagonistic, global systems: (i) a system of externally oriented, sensory-motor networks (the "extrinsic" system); and (ii) a system of inward-oriented networks (the "intrinsic" or default system). According to this framework, four distinct mental states would be possible that could be relevant for understanding DOCs. In normal healthy volunteers and locked-in syndrome patients, a state of high functionality of both the extrinsic and intrinsic or default systems is expected--associated with full awareness of environment and self. In this case, mental imagery tasks combined with fMRI can be used to detect covert awareness in patients that are unable to communicate. <br /> <br />According to the framework, two complementary states of system imbalance are also possible, in which one system is in a hyperfunctional state, while the other is hypoactive. Extrinsic system hyperfunction is expected to lead to a state of total sensory-motor "absorption" or "lost self." In contrast, intrinsic or default system hyperfunction is expected to lead to a state of complete detachment from the external world. A state where both extrinsic and intrinsic systems are hypofunctional is predicted to lead to markedly impaired consciousness as seen in DOCs. Finally, we review the potential use of ultra-slow fluctuations in BOLD signal as a tool for assessing the functional integrity of extrinsic and intrinsic systems during "resting state" fMRI acquisitions. In particular, we discuss the potential provided by assessment of these slow spontaneous BOLD fluctuations as a novel tool in assessing the cognitive state and chances of recovery from brain pathologies underlying DOCs.
Disciplines :
Neurology
Neurosciences & behavior
Author, co-author :
Soddu, Andrea ;  Université de Liège - ULiège > Centre de recherches du cyclotron
Boly, Mélanie ;  Université de Liège - ULiège > Département des sciences cliniques > Neurologie
Nir, Yval
Noirhomme, Quentin ;  Université de Liège - ULiège > Centre de recherches du cyclotron
Vanhaudenhuyse, Audrey  ;  Université de Liège - ULiège > Centre de recherches du cyclotron
Demertzi, Athina  ;  Université de Liège - ULiège > Centre de recherches du cyclotron
Arzi, A.
Ovadia, S.
Stanziano, M.
Papa, M.
Laureys, Steven  ;  Université de Liège - ULiège > Centre de recherches du cyclotron
Malach, R.
Language :
English
Title :
Reaching across the abyss: recent advances in functional magnetic resonance imaging and their potential relevance to disorders of consciousness
Publication date :
2009
Journal title :
Progress in Brain Research
ISSN :
0079-6123
eISSN :
1875-7855
Publisher :
Elsevier, Amsterdam, Netherlands
Volume :
177
Pages :
261-274
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
ISF - Israel Science Foundation [IL]
MIUR - Ministero dell'Istruzione, dell'Università e della Ricerca [IT]
EC - European Commission [BE]
JSMF - James S McDonnell Foundation [US-MO] [US-MO]
MSF - Mind Science Foundation [US-TX]
FMRE - Fondation Médicale Reine Elisabeth [BE]
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