CarolineSchnakers, BASc, Cyclotron Research Center and Department of Neurology, University of Liège,, Sart Tilman B30, 4000 Liège, Belgiumc.schnakers@student.ulg.ac.be
Mélanie Boly MD, Steve Majerus PhD, Steven Laureys, MD, PhD
Submitted April 16, 2005
We thank Dr. Machado for his comments on our article. It is important
to stress that recent functional imaging studies [1] have shown that
vegetative patients are not a-pallic (i.e., still may show preserved
islands of functional "pallium" or cortex) and that the condition can be
reversible and should benefit from aggressive therapy, especially in the
in the acute and subacute phase.
We agree that consciousness is a first person subjective
experience which is difficult to evaluate at the patient’s bedside but
differ with Machado’s view when he states that “subjective awareness might
continue in some VS cases”. Phenomenal consciousness is contingent upon
the integrated coherent involvement of a widely distributed global
neuronal workspace [2] and not merely upon the isolated activation of
disconnected primary cortices which has been observed in well-documented
vegetative state patients. [1] This is important regarding conscious
perception of pain in the persistent vegetative state. [3]
As Machado pointed out, the current challenge for the
medical community is to disentangle differences in brain function in
individual patients evolving from a vegetative state into a minimally
conscious state and to use this knowledge in the assessment of new
therapeutic strategies. [4,5]
References
1. Laureys S, Owen AM, Schiff ND. Brain function in coma,
vegetative state, and related disorders. Lancet Neurol 2004;3:537-546.
2. Baars B, Ramsoy T, Laureys S. Brain, conscious experience and
the observing self. Trends in Neurosciences 2003;26:671-675.
3. Laureys S, Faymonville ME, Peigneux P, et al. Cortical
processing of noxious somatosensory stimuli in the persistent vegetative
state. Neuroimage 2002;17:732-741.
4. Boly M, Faymonville ME, Peigneux P, et al. Auditory processing
in severely brain injured patients: differences between the minimally
conscious state and the persistent vegetative state. Arch Neurol
2004;61:233-238.
5. Schiff ND, Rodriguez-Moreno D, Kamal A, et al. fMRI reveals
large-scale network activation in minimally conscious patients. Neurology
2005;64:514-523.
We thank Dr. Machado for his comments on our article. It is important to stress that recent functional imaging studies [1] have shown that vegetative patients are not a-pallic (i.e., still may show preserved islands of functional "pallium" or cortex) and that the condition can be reversible and should benefit from aggressive therapy, especially in the in the acute and subacute phase.
We agree that consciousness is a first person subjective experience which is difficult to evaluate at the patient’s bedside but differ with Machado’s view when he states that “subjective awareness might continue in some VS cases”. Phenomenal consciousness is contingent upon the integrated coherent involvement of a widely distributed global neuronal workspace [2] and not merely upon the isolated activation of disconnected primary cortices which has been observed in well-documented vegetative state patients. [1] This is important regarding conscious perception of pain in the persistent vegetative state. [3]
As Machado pointed out, the current challenge for the medical community is to disentangle differences in brain function in individual patients evolving from a vegetative state into a minimally conscious state and to use this knowledge in the assessment of new therapeutic strategies. [4,5]
References
1. Laureys S, Owen AM, Schiff ND. Brain function in coma, vegetative state, and related disorders. Lancet Neurol 2004;3:537-546.
2. Baars B, Ramsoy T, Laureys S. Brain, conscious experience and the observing self. Trends in Neurosciences 2003;26:671-675.
3. Laureys S, Faymonville ME, Peigneux P, et al. Cortical processing of noxious somatosensory stimuli in the persistent vegetative state. Neuroimage 2002;17:732-741.
4. Boly M, Faymonville ME, Peigneux P, et al. Auditory processing in severely brain injured patients: differences between the minimally conscious state and the persistent vegetative state. Arch Neurol 2004;61:233-238.
5. Schiff ND, Rodriguez-Moreno D, Kamal A, et al. fMRI reveals large-scale network activation in minimally conscious patients. Neurology 2005;64:514-523.