Question: Hey Kim! It's me again, we were having a conversation about rewriting genetic codes and people in a live chat today. It was a little hectic since I asked you my question at the end so I didn't get to properly process your answer. But, I actually spend an unhealthy amount of time just thinking about the conscious and where it comes from. (I'm no expert which you can probably tell :) ) But I was thinking that it might be in the brain since even when the heart stops beating the person is still alive for a little while afterwards until the brain is deprived of oxygen. The brain, on the other hand, stops working and the body dies immediately. What do you think?

Nina Rzechorzek answered on 8 May 2020: last edited 8 May 2020 3:32 am

Such an interesting question Lynette, and it’s becomes pretty mind-blowing to start thinking about ‘how we think’ so I can sympathise with your anxiety about this – but it’s totally natural to wonder about it!
Firstly, much of the processing carried out by the brain is unconscious – explored a great deal in the 19th and 20th centuries by Herman Helmholtz and Sigmund Freud, respectively.
Second, ‘consciousness’ poses fundamental problems for a biological theory of ‘mind’. What we commonly call ‘mind’ is a set of operations carried out by the brain. Because consciousness is a fundamental property of mind, it must also be a function of the brain and so we should be able to identify neural circuits that are responsible for it. But, to test theories of consciousness in scientific terms, we need to be able to define it so here goes…
Consciousness can be thought of as a state of self-awareness with three essential features: subjectivity, unity, and intentionality
(1) Subjectivity – our own ideas, moods, and sensations are experienced directly – we cannot know that what we experience when smelling e.g. coffee is experienced in exactly the same way by someone else
(2) Unity – our experience of the world at any given moment is felt as a single unified experience (if you are sitting to read this you will be experiencing the chair you are sitting on, the light from the screen, maybe some noise in your surroundings, all at once)
(3) Intentionality – our conscious experience connects successive moments and we have the sense that successive moments are directed toward some goal
However, others have defined the following three components of consciousness:
(1) Cognition – deriving knowledge through thinking and reasoning
(2) Emotion
(3) Will
As you can see, the definition of consciousness is still heavily debated, and some scientists even think that consciousness is so complex, that it is beyond human intelligence to be able to understand it. Much of the difficulty comes with trying to objectively assess consciousness – especially the subjectivity part – how do I know that when we both look at the same blue object, we are both seeing the same blue? We do not currently know if or how the firing of a specific set of neurons in the brain leads to conscious perception. There has however been amazing progress in understanding the neurobiology of sensory perception, without having to account for individual experience (in other words, we don’t need to know how consciousness works in order to study cognitive processes such as learning and memory). Many neuroscientists think that the brain connections responsible for consciousness are widely distributed in the brain, rather than being localised to one specific area. Certainly, given the ‘unity’ aspect of consciousness, consciousness must involve modulatory control over a variety of neural systems simultaneously. Perhaps the simplest definition of consciousness is as an integrated function of the brain that supports voluntary behavioural responses. From a neuroanatomical point of view, we consider the brain’s cerebral cortex to be essential for consciousness, which is why damage in these regions can affect how we perceive the world around us, in subtle, or severe ways. From a clinical point of view, I see abnormal levels of consciousness in patients with cerebral cortex or brainstem injury – I find it helpful to think of the brainstem as the ‘gateway’ to consciousness (the ‘gateway’ to the cortex). Our poor understanding of consciousness makes it very difficult to know how best to assess and manage patients in a vegetative state after major brain injury and this website explains why:

Vegetative State

We certainly don’t need to be conscious to be alive – which is why patients can recover fully from general anaesthesia and from generalized epileptic seizures. Currently the official legal definition of death in UK law is brainstem death – because this region contains the neural circuits required for basic functions to sustain independent life (like breathing). Once those circuits are lost or damaged, they cannot be repaired. From a practical point of view, death occurs when there is permanent loss of capacity for consciousness AND loss of all brainstem functions (hence patients in a coma are still alive even though they have lost consciousness).