The Minimally Conscious State

意識是如此不可捉摸又抽象的概念，「測量」意識簡直就像科幻小說情節。科學家近年來在這方面已大有進展，藉由各項腦造影技術和實驗手法，能夠分析不同意識狀態下的大腦活動型態。.

Disorders of consciousness (DoC)—that is, unresponsive wakefulness syndrome/vegetative state and minimally conscious state—are debilitating conditions for which no reliable markers of consciousness recovery have yet been identified. Evidence points to the GABAergic system being altered in DoC, making it a potential target as such a marker.

One of the final obstacles to understanding consciousness in physical terms concerns the question of whether conscious states can exist in posterior regions of the brain without active connections to the brain's prefrontal lobes. If they can, difficult issues concerning our knowledge of our conscious states can be resolved. This paper contains a list of types of conscious states that may meet this criterion, including states of coma, states in which subjects are absorbed in a perceptual task, states in brains (...) with damaged prefrontal lobes, states of meditation and conscious states of some infants and animals. Recent evidence also suggests that conscious states of some people with autism may meet this criterion. (shrink)

Disorders of consciousness include coma, the vegetative state and the minimally conscious state. Such patients are often regarded as unconscious. This has consequences for end of life decisions for these patients: it is much easier to justify withdrawing life support for unconscious than conscious patients. Recent brain imaging research has however suggested that some patients may in fact be conscious.

Recent work in neuroimaging suggests that some patients diagnosed as being in the persistent vegetative state are actually conscious. In this paper, we critically examine this new evidence. We argue that though it remains open to alternative interpretations, it strongly suggests the presence of consciousness in some patients. However, we argue that its ethical significance is less than many people seem to think. There are several different kinds of consciousness, and though all kinds of consciousness have some ethical significance, different (...) kinds underwrite different kinds of moral value. Demonstrating that patients have phenomenal consciousness — conscious states with some kind of qualitative feel to them — shows that they are moral patients, whose welfare must be taken into consideration. But only if they are subjects of a sophisticated kind of access consciousness — where access consciousness entails global availability of information to cognitive systems — are they persons, in the technical sense of the word employed by philosophers. In this sense, being a person is having the full moral status of ordinary human beings. We call for further research which might settle whether patients who manifest signs of consciousness possess the sophisticated kind of access consciousness required for personhood. (shrink)