Your other brain?
You probably imagine that you do all your mental work – perceiving, analysing, thinking, feeling and so on – with your brain – that organ inside your skull. However, we’ve known for some time that there are networks of neurones around the hollow organs of the body, especially around the heart and the intestines. We’ve also discovered “neurotransmitters” originating from those parts of the body. So, at very least, we are aware that there are two way connections between the heart and the brain, and the gut and the brain.
A recent article in New Scientist magazine described the network around the gut and named it the “Enteric Nervous System” (ENS). There are around 500,000 neurones around the gut (where there are about 85 billion in the brain). Most surprisingly, alongside the 40 or so neurotransmitters in this network, two chemicals known to affect mood and mental functions, dopamine and serotonin, are also present. In fact, it is now thought that 50% of all dopamine is produced in the brain, and 50% in the ENS. Only 5% of serotonin is produced by the brain, and 95% of it in the ENS. This is quite astonishing when you consider the roles these hormones can play in our behaviour.
The other fascinating fact the author of the New Scientist article highlights is the presence of Lewy bodies in the ENS (these are the pathological lesions seen in the brains of patients with Parkinsons Disease), and patients with Alzheimer’s have characteristic lesions on both their brain and ENS neurones. Do those “neurological” diseases begin in the brain, or in the gut?
It’s good to see scientists discovering how interlinked our bodily systems are, and how difficult it is to reduce a person to parts – even the two parts of Mind and Body. Are those parts really such separate parts of they are so connected and inter-related?