• 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?

    Asked by Lynette C. to Nina, Kim on 7 May 2020.
    • Photo: Kim Liu

      Kim Liu answered on 7 May 2020: last edited 7 May 2020 6:30 pm

      Hi Lynette! Thanks for resuming the chat 🙂 My first comment: Honestly – I can’t really imagine what an unhealthy amount of time thinking about the consciousness is haha. Probably if you don’t sleep for days on end! Otherwise – I think questions regarding what the consciousness is and how it works are incredibly important; understanding why humans think as they do is of immense value to everyone. As a disclaimer – I’m not really going to be giving any definite scientific answers – I’m just going to leave more ideas to think about. It may be that science cannot fundamentally tackle this question (search Wilhelm Wundt). Also, I’m no more an expert on this subject than you, so I’d be pleased if Nina and others weigh in and suggest ideas/critiques also!


      First – it is not unreasonable to assume that the consciousness resides within our brain, since that is where all ‘higher-order human functions’ of personality, rationality, emotions and others probably reside, as judging from fMRI scans. So a standard experiment might be to show pictures which elicit an emotional etc. response, and then observe areas of the brain responding by increased blood flow. The consciousness is most commonly associated with the cerebral cortex, and there are other structures associated with more specific functions. So overall, given that certain consciousness-associated function seems to be linked with parts of the brain, it is indeed probably ‘contained’ there.

      As for the rest of the body, it seems unlikely to me that consciousness is stored there – there have been numerous amputations and organ transplants throughout history that don’t seem appear to result in a change of consciousness. With respect to what you’ve written – the heart stops immediately because the brain is constantly sending signals telling the heart muscle to pump, which is why it stops almost immediately upon brain death (defining death – a difficult question for doctors!) I would suggest that it is not necessarily due to any issues of consciousness. The correlation/causation issue is a very challenging aspect of doing science, even when the consciousness is not involved! Since the it is possible for the heart to stop and then restart without seeming changes in consciousness, this suggests to me that it is not related.


      Interestingly, similar observations can be made for animals, and now and in the future, robots can be made that will simulate the results of rationality, emotion and personality. Consciousness-es of animals and robots are also questions that need answering. Part of the problem is defining ‘consciousness’ – what precisely does it mean? We have an intuitive sense for sure, but science and logic demand something more. A definition I like is that a conscious being has a subjective experience, which is to say it experiences an undefined, non-quantifiable ‘feeling’ associated with a given observation. This also leads to why science may not be able to solve the question of consciousness. Science requires objective evidence to work well, and the outcomes of consciousness may require introspection to obtain that data, which by its nature will probably end up changing that data. Or – there is the Matrix issue, or the brain-in-the-box, which suggest that it is impossible to know whether or not we’re all in a very vivid dream, and our senses we use to investigate consciousness are therefore limited. This is not an issue for the majority of science, which acts independently of our existence, but for consciousness, it feels more important to me.

      All of this has, of course, huge implications on ethics and human values, which I will not write about now. Suffice to say – this has been a pressing issue for philosophers since the dawn of civilisation. Thanks for giving me the chance to do some reading, learn more, and write this answer. Looking forward to further questions or comments, if you are so inclined 🙂

    • Photo: Nina Rzechorzek

      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).