I want to start 2013 by putting forward two provocative ideas. One is to challenge the conventional division between the brain and the rest of the body. The second is to promote the concept of ‘brainfulness’. Neither idea is entirely original. Both emerge from ways of thinking that have been around for some time. If you do a web search for ‘brain–body divide’ and brainfulness, you will find a large number of results, although if you follow them up, you will find they are rather insubstantial. I suggest that 2013 is the time to develop these two ideas further.

The brain–body divide is, self-evidently, an artificial one. No doctor needs to be reminded that the brain is contiguous with spinal cord and peripheral nervous system, which in turn are contiguous with our muscles. In embryological terms, our eyes, skin, and the lining of some of our gut are derived from the same ectodermal tissue as the brain. Although there may be sound pragmatic reasons in medicine for declaring that the thing we call a ‘brain’ starts and finishes in particular places, a moment's reflection will make it obvious that this is arbitrary. It has only been established by convention. There is no intrinsic reason to define the brain as stopping at the medulla and pons rather than at the cauda equina, for example, or indeed the finger tips.

In reality, we know that our ‘brains’ are in a constant state of two-way communication with all our other bodily parts and organs. Our sentience doesn't consist only in what our brain tells us: it resides in the combined information that passes to and fro, both electrically and chemically, between every one of our senses, and between every one of our cells. It also encompasses our responses to the people we happen to be looking at, talking with, or embracing. The person you see opposite you—your friend, your spouse, or yourself in the mirror—is in effect nothing but an extended and intercommunicating brain, dressed up in clothes and wearing shoes.

This might seem to be a rather abstract point, more suited to a philosopher's dining room than deserving the attention of doctors. I think such a view would be wrong. One of the most passionate and longstanding debates in the medical world relates to the so-called ‘mind–body problem’, or ‘mind–brain problem’.1 This debate is especially active in areas of research like unexplained pain, where patients and doctors, unless they are careful, can get into pointless squabbles about whether problems are ‘all in the mind’.2 Although there are fundamentalists who argue that any disorder can be created only by the body, and others who argue pretty much the opposite, most people these days seem to agree that such extreme positions are unhelpful. A more useful stance, sometimes described as ‘dual aspect monism’, regards body-based explanations and mind-based explanations just as different perspectives on the same phenomena.3