Consciousness

Principal Researchers:  Prof. N. Levy, Prof. J. Savulescu, Dr H. Madder, Prof. B. Fulford.

Further Researchers:  Dr L. Skene, Dr G. Kahane, Dr N. Shea, Dr D. Wilkinson, Dr K. Wiech.

The Terri Schiavo case illustrates the controversy surrounding patients diagnosed in persistent vegetative states (PVS). This diagnosis is made when patients exhibit preserved sleep/wake cycles but appear unaware of self and environment ( Howsepian 1996) . Since consciousness is sometimes intermittent, neurologists can miss it (Fins 2006), and PVS is reportedly frequently misdiagnosed ( Andrews et al. 1996). However, there is also a risk that untrained and hopeful observers will be misled by the spontaneous movements and vocalizations which occur in PVS. Neuroimaging promises to settle this diagnostic issue by making possible direct measurement of the brain activity underlying consciousness. Although neuroscientists and philosophers are yet to identify the ‘neural correlates of consciousness’ (Koch 2004) there is already suggestive evidence indicating awareness in patients diagnosed as PVS (Schoenle & Witzke 2004). The most striking findings are those of Owen et al. (2006) who used fMRI to scan the brain of a woman diagnosed as PVS to demonstrate not only linguistic processing, but apparent instruction following. They claim their findings constitutes proof that the patient is conscious.

These claims remain controversial (Greenberg 2007). One alternative interpretation is that the patient is merely exhibiting cognitive processing in the absence of consciousness; another is that the patient was transitioning from PVS to minimal consciousness. The most exciting possibility is that some patients who meet all the behavioural criteria for PVS are indeed conscious. If this is so, fMRI might become a diagnostic or even communication tool. Owen et al are conducting experiments where patients can indicate “yes” or “no” using mental imagery (Personal Communication), opening up the possibility of communication with patients previously thought to be unconscious.

These studies raise questions about consciousness and its ethical significance that cannot be answered by neuroscience alone. Philosophical and ethical expertise is required to guide the development of clinical practice:

1. What would be adequate criteria for ascribing consciousness to severely brain-damaged patients?

  We shall bring together relevant work from neuroscience and philosophy of mind to identify criteria for consciousness that can then be used to interpret existing neuroscientific findings as well as to guide empirical research. We shall also explore whether the criteria we identify can be applied to other cases where the ascription of consciousness is controversial, such as lower animals and foetuses (see Farah 2008), or brain damaged neonates (Wilkinson 2006).

2. What is the moral significance of consciousness ?

Philosophers distinguish two senses of consciousness: phenomenal consciousness (qualitative feel of experiences) and access consciousness (availability of information for rational control of action) (Block 1995).. Phenomenal consciousness is needed to experience pain and pleasure. However, a good life seems to require sophisticated cognitive abilities, such as the ability to recall one’s past, to plan and have preferences for how one’s life goes (Singer 1993; McMahan 2002), which require access consciousness. We need to ascertain what kind of consciousness is being attributed to patients in fMRI studies and how this bears on well-being and value of life (Kahane & Savulescu 2009), and its implications for treatment (Wilkinson, Kahane & Savulescu, under review). This research programme will be extended to examine the relevance to , well-being of different aspects of mental life, and applied to other forms of severe neurological impairment.

 

References

 

Andrews, K., Murphy, L., Munday, R., & Littlewood, C. (1996), 'Misdiagnosis of the vegetative state: retrospective study in a rehabilitation unit, BMJ, 313: 13-16.

Block, N. (1995), 'On a confusion about a function of consciousness,' Behavioral and Brain Sciences 18: 227-287.

Farah, M.J. (2008), 'Neuroethics and the Problem of Other Minds: Implications of Neuroscience for the Moral Status of Brain-Damaged Patients and Nonhuman Animals,' Neuroethics, 1: 9-18.

Fins, J.J. (2006), 'Affirming the right to care, preserving the right to die: Disorders of consciousness and neuroethics after Schiavo,' Palliative and Supportive Care, 4: 169–178.

Greenberg, D.L. (2007), Comment on “Detecting Awareness in the Vegetative State,” Science 315,1221b.

Howsepian, A.A. (1996), 'The 1994 Multi-Society Task Force Consensus Statement on the Persistent Vegetative State: A Critical Analysis,' Issues in Law & Medicine, 12: 3-29.

Kahane, G. & Savulescu, J. (2009), 'Brain-Damaged Patients and the Moral Significance of Consciousness,' The Journal of Medicine and Philosophy, 33: 1-21.

Koch, C. (2004), The Quest for Consciousness: A Neurobiological Approach,Roberts & Company.

McMahan, J. (2002), The Ethics of Killing, Oxford: Oxford: Oxford University Press.

Owen, A.M., Coleman, M.R., Boly, M., Davis, M.H., Laureys, S. &. Pickard, J.D. (2006), 'Detecting Awareness in the Vegetative State,' Science 5792: 1402.

Schoenle, P.W. & Witzke, W. (2004), 'How vegetative is the vegetative state? Preserved semantic processing in vegetative state patients: evidence from N 400 event-related potentials,' Neurorehabilitation, 19: 329-334.

Singer, P. (1993), Practical Ethics, Cambridge: Cambridge University Press.

Wilkinson, D. (2006), 'Is it in the best interests of an intellectually disabled infant to die?' Journal of Medical Ethics, 32: 454-459.

Wilkinson, D., Kahane, G., Horne, M. & Savulescu, J. (2009), 'Functional neuroimaging and Withdrawal of Life-sustaining Treatment from Vegetative Patients,' Journal of Medical Ethics, 35 (8): 508-511.