Consciousness is at once the most familiar and the most mysterious feature of our existence. A new science of consciousness is now revealing its biological basis. Here are eight key questions that neuroscientists are now addressing:Seth closes with what is perhaps the most interesting question: Why is consciousness part of the universe at all? Indeed, even if consciousness can ultimately be explained purely in terms of material processes, something many philosophers deeply doubt, it is hard to imagine how or why it should have arisen in a purely mechanistic, naturalistic world in the first place. So, if not, where did it come from?
1. What are the critical brain regions for consciousness?
We now think that consciousness depends primarily on a specific network of regions in the cortex (the wrinkled surface of the brain) and the thalamus (a walnut-sized structure buried deep in the interior). Some of these regions are important for determining the level of consciousness (the difference between waking and dreamless sleep) while others are involved in shaping conscious content (the specific qualities of any given experience).
2. What are the mechanisms of general anaesthesia?
A good way to study a phenomenon is to see what happens when it disappears. General anaesthesia can be induced by many different substances but the outcome is the same: total loss of consciousness. There is now increasing evidence that anaesthesia involves a disintegration of how different parts of the brain work together, a sort of "cognitive unbinding" rather than a general shutting-down.
A key question now is how similar general anaesthesia is to other states of unconsciousness, such as dreamless sleep.
3. What is the "self"?
Selfhood is a complex phenomenon, encompassing a first-person perspective on the world, a sense of ownership of our body, actions, and thoughts, perceptions of our internal physiological condition, and of course the narrative we tell ourselves about our past experiences and imagined futures.
We now know that these different features depend on different brain mechanisms, and can even be manipulated experimentally (for example, it's possible to generate "out of body" experiences in the lab). Understanding how the brain constructs the conscious self will help us better understand and treat psychiatric disorders such as schizophrenia, which involve a disintegration of selfhood.
4. What determines experiences of volition and 'will'?
The question of whether "free will" exists is guaranteed to raise philosophical hackles. Neuroscientists have studied this issue since the 1980s by looking for neural signatures of volition (the experience of intending to do something) and agency (the experience of causing an action). A growing consensus now rejects the idea of volition as explicitly causing actions, instead seeing it as involving a particular brain network mediating complex, open decisions between different actions.
5. What is the function of consciousness? What are experiences for?
Researchers have now discovered that many cognitive functions can take place in the absence of consciousness. We can perceive objects, make decisions, and even perform apparently voluntary actions without consciousness intervening. One possibility stands out: consciousness integrates information. According to this view, each of our experiences rules out an enormous number of alternative possibilities, and in doing so generates an incredibly large amount of information.
6. How rich is consciousness?
This evidence may provide a basis for tackling one of the thorniest problems in consciousness science: distinguishing the brain mechanisms of consciousness itself from those involved in being able to relate what we experience.
7. Are other animals conscious?
Mammals share much of the neural machinery important for human consciousness, so it seems a safe bet to assume they are conscious as well, even if they can't tell us that they are. Despite this similarity, animal consciousness is unlikely to involve conscious selfhood in the same sense that humans enjoy.
8. Are vegetative patients conscious?
In the US alone, about 15,000 patients are in a "vegetative state", having suffered massive brain injury. The key feature of this state is that patients' behaviour suggests that they are awake but not aware. Brain imaging has revealed, however, that at least some of these patients are conscious, and has even facilitated communication between these patients and their families and doctors.
Tuesday, November 4, 2014
In an article in The Guardian a couple of years ago, Anil Seth listed eight problems concerning consciousness that neuroscientists are investigating. The article presupposes a materialist view of the subject but even one who finds materialism to be an incomplete account of human ontology will find the questions fascinating. Seth lists and gives a brief summary of each of the eight. I've made his summaries even more brief and urge interested readers to visit the link for more detail. Seth writes:
at 3:09 PM