The Science of Consciousness:

Chapter 10: Consciousness and the Brain

What this chapter is about: How is consciousness related to the brain?

What are the neural correlates of consciousness (NCCs)?

Perhaps "Consciousness and the brain" was a slightly misleading title for this chapter, because it also includes discussion of neurotransmitters. "The biology of consciousness" is a more general title, but then related material appears in other chapters too, such as the chapters on perception, sleep, and drugs, among others. Oh well. The material has to be organised somehow.


Correction

p. 258. Figure 10.8 legend says "Death corresponds to being permanently at the origin". That isn't right - death corresponds to maximum unconsciousness and zero arousal, so is in the furthest bottom left of the graph, more extreme than coma. I should add the graph is schematic and there are no units for degree of consciousness or arousal. Perhaps the graph would be clearer as a standard graph rather than overlapping x and y scales with four quadrants.


Additional material

Fear of death. I admit to being morbidly obsessed with what happens when we die. But death is, we assume, eventually the final loss of consciousness, so the study of death and dying is informative for understanding consciousness. Notice I say “eventually”; that’s because we have to define death, and different people have different definitions. If you define death as the permanent cessation of all respiratory and cardiac function the brain continues to function for a while after that. And if you talk about brain death, what about different parts of the brain dying at different rates? What if the brainstem is still functioning while higher functions have ceased? I cover all these topics in the book.I don't know why more people aren't scared of dying. I'm terrified of my death (and of loved ones, including Beau), to the extent that yes, it interferes with my quality of life. I have thanatophobia. This page asserts that this phobia generally peaks in one's twenties and then declines, but sadly I am older than that, and the older I get the more intense my fear becomes. I think the fear of a loved one dying and fear of my own death are related but distinct. Most people are scared of a loved one dying, but I think I worry about it more than most. It is however the fear of my own death that obsesses me most. How can there be a world without me? Being told that there was a world before me that got along perfectly well doesn't help. And what is it like never to wake up? Why don't you people worry that you might not wake up tomorrow? How can you all be so - unconcerned? I know in principle it's like falling into a dreamless sleep for ever, and therefore not like anything, but that doesn't help me either. And talking of Beau, I'm pretty sure he's not afraid of dying. Never say ever, but I doubt very much that any animal has ever been afraid of dying; perhaps fear of death is what makes humans unique among animals (see Chapter 5). See my blog post for more on thanatophobia.


Anaesthesia

In 2019 I had a minor operation on my wrist, and for the first time in living memory was given a general anaesthetic. It was propofol, and I tried to count down and resist while going under. It was of course hopeless, and after about four seconds succumbed. For me it was like going into a deep dreamless sleep. I woke up 45 minutes later feeling bright and breezy. I had had gas (nitrous oxide) many decades ago at the dentist, but don't remember much about it, other than counting to ten and reaching four before waking up with everything done. I don't remember feeling odd waking up then, either.


Molecular consciousness

While the neural correlates of consciousness (NCC) are concerned with which brain structures are involved in generating and maintaining consciousness, the biological correlates of consciousness (which we might term BCC) are concerned with a yet lower level, at the synaptic and neurotransmitter levels. The term molecular consciousness has come into use for the way in processes beneath the level of brain structures might be involved in consciousness.

Note that the term molecular consciousness refers to the role of the molecular level in generating consciousness, not consciousness at the molecular level (which does make some sense in the context of panpsychism. See Chapter 2 on reductionism.

Bickle, J. (2006). Reducing mind to molecular pathways: explicating the reductionism implicit in current cellular and molecular neuroscience. Synthese, 151, 411–434. https://doi.org/10.1007/s11229-006-9015-2


Links to research on dying

Coma. UAE woman Munira Abdulla wakes up after 27 years in a coma. Murina Abdulla was 32 when she was involved in a traffic accident in 1991. She was diagnosed as being in a vegetative state and moved around hospitals before being given therapy in Germany. In 2018 she said the name of her son, Omar (who was four at the time of the accident). She become more responsive, can carried out limited conversation, and feel pain.

Thousands in vegetative state are conscious. In The Times, "Thousands of people thought to be in a vegetative state are awake and locked in unresponsive bodies, experts in the field say. ... Research studies have shown that using MRI scans or bedside electroencephalogram (EEG) can detect consciousness in some men and women thought to have no awareness of what is going on around them. Techniques include asking them to visualise a face or a house, which activate different areas of the brain, or seeing if their brain patterns while watching a film echo those measured in fully conscious audiences." See: Scolding, N., Owen, A. M., & Keown, J. (2021). Prolonged disorders of consciousness: a critical evaluation of the new UK guidelines. Brain, 144, 1655-1660. https://doi.org/10.1093/brain/awab063


Death. https://www.news-medical.net/health/What-Happens-to-the-Brain-After-Death.aspx. Electrical activity persists for 10-15 seconds in a decapitated rat brain, but large, slow waves are observed 50-80 s after decapitation: the "wave of death" associated with mass neuronal depolarisation as neurons lose their electical abilities.

van Rijn, C. M., Krijnen, H., Menting-Hermeling, S., & Coenen, A. M. L. (2011). Decapitation in rats: Latency to unconsciousness and the “wave of death.” PLoS ONE, 6(1), 1–6. https://doi.org/10.1371/journal.pone.0016514

Norton, L., Gibson, R. M., Gofton, T., Benson, C., Dhanani, S., Shemie, S. D., … Bryan Young, G. (2017). Electroencephalographic Recordings during Withdrawal of Life-Sustaining Therapy until 30 Minutes after Declaration of Death. Canadian Journal of Neurological Sciences, 44 (2), 139–145. https://doi.org/10.1017/cjn.2016.309

Vrselja, Z., Daniele, S. G., Silbereis, J., Talpo, F., Morozov, Y. M., Sousa, A. M. M., … Sestan, N. (2019). Restoration of brain circulation and cellular functions hours post-mortem. Nature, 568 (7752), 336–343. https://doi.org/10.1038/s41586-019-1099-1


Further reading on dying

Crowley, A. (1913). The testament of Magdalen Blair. In my opinion the best fictional account about the process of dying and being dead - and it's not portayed as a pleasant experience.

Shafak, E. (2019). 10 minutes 38 seconds in this strange world. London: Penguin. Set in Turkey, this short-listed for the Man Booker Prize, this novel describes the final moments of consciousness of a person after death. The title refers to the length of time the protagonist has awareness and memories after "death", although I am unable to find any reference supporting the idea that any brain processing persists this long. It's a curiously precise time.

Michael, P. (2020). Neurothanatology: The quest for the NDE-ogen. The Paranormal Review, 95, 14-16. This short review wxamines the supposed similarities between DMT (dimethyltryptamine) "trips" and NDEs (near-death experiences).

Li, D., Mabrouk, O. S., Liu, T., Tian, F., Xu, G., Rengifo, S., … Borjigin, J. (2015). Asphyxia-activated corticocardiac signaling accelerates onset of cardiac arrest. Proceedings of the National Academy of Sciences of the United States of America, 112(16), E2073–E2082. https://doi.org/10.1073/pnas.1423936112 Asphyxia brings on a flood of neurotransmitters and increases electrical coherence in rat brains, markers of possible enhanced cognitive activity (relating to NDEs in cardiac arrest).


Further questions to think about

1. What ethical issues are raised by being able to read people's thoughts by brain imaging, and how should any issues be resolved?