The mind-body problem is probably the most important issue in the philosophy of mind. It attempts to account for the existence of consciousness and dates back centuries or millenia. In its time, it's taken the form of psychophysical dualism - the idea that the soul is of one substance and the body another, which introduces the problem of how they would interact - behaviourism - the idea that mental states are nothing but what can be observed by others in principle - functionalism - the subject of an upcoming video but basically the idea that we are networks of computer-like components - and anomalous monism - the idea that there is a physical state for every state of mind but that there is no law-like relationship between them. There are a number of other attempts to solve the mind-body problem, including one which has been popular for the duration of the industrial era, namely physicalism.
I have no intention of criticising physicalism here, although it's not what i believe for complicated and irrelevant reasons, but every intention of criticising the commonly-stated adage used to sum it up: "I am my brain". I think that's from Thomas Nagel, incidentally. Well, I am not my brain at all, and here's an explanation why.
My brain is clearly vital to my self-awareness and self-identity, though less so to my awareness and identity. The reason i say that is that my brain is a lump of neurones interacting with each other via neurotransmitters and action potentials, supported by the 90% of non-neuronal cells making it up and so forth, but although there is a blood-brain barrier, the "border" of the brain which is fairly firmly policed, there are plenty of other cells in the nervous system. If i was my brain, where does my brain end? Is it at the medulla oblongata? Does it include the whole of the spinal cord? Am i less than my whole brain? Why not include the autonomic nervous system, responsible for fear, panic and calm? Why is it more important that depression is related to serotonin levels than oxygen supply, blood glucose levels and via those, insulin levels, and the like? Why is adrenalin secreted by a neurone part of me but not adrenalin secreted by my adrenal medulla? Why are the steroid hormones related to my sex drive not also part of my identity?
Before i move on to the next bit, here's a thought experiment, explored in the past by Robert A Heinlein in 'I Will Fear No Evil'. A man has his brain transplanted successfully into the body of his literally brain-dead female secretary and the resultant person becomes attracted to men. I think this is entirely feasible, although i'm not sure about the idea of sex hormones doing it because - well, ich muss schweigen. However, clearly a brain transplanted into a person with the bowels of mercy, or maybe just nervous diarrhoea (and let's face it, who wouldn't have nervous diarrhoea at the prospect of a brain transplant?), would involve the formation of a new identity inside and out.
And out: We are not our bodies any more than we're our brains, not because physicalism isn't true but because we are social beings perceived to be various things by other people and we can't escape that. This brings me to my main point. It has now been borne in upon me that for whatever reason, most of the cells in my brain are XX rather than XY and that its structure and size are accordingly more like a typically female brain than a male one, but it's sitting there in a male head with a male endocrine environment with a load of people perceiving the body it's in, including itself as it happens, as male, so it really is male.
Just thought it was a neat illustration of why "I am my brain" is completely wrong.