Modern neuroscience is barely 200 years old, and for much of that time, a central dogma of the field held that we are born with all the brain cells we will ever have, and that that adult brain is immutable, like clay that hardens after being poured into a mould.
That began to change about 50 years ago, however, as new evidence began to emerge – evidence that the brain continues to produce new cells throughout life, and that it can adapt in response to learning, injury, and other experiences.
It is now widely accepted that the brain changes continuously from the cradle to the grave, and the term neuroplasticity is used to refer to the many ways in which it can do so.
Recently, however, neuroplasticity has captured the public imagination, and the idea that the brain can “rewire” itself to adapt to just about anything has taken firm hold. The old dogma that the brain cannot change has been replaced by the new dogma that it can rewire itself to achieve just about anything, and the term neuroplasticity has been hijacked by self-help gurus and charlatans who use it to give an air of scientific credibility to their products and services.
A quick internet search reveals thousands of websites and books purporting to harness the power of neuroplasticity. You can, apparently, rewire your brain to find love and happiness, to think positively, to lose weight, to get rich, or transform your life in some other way.
Neuroscientists sometimes abuse the term, too. Brain training companies evoke the concept to bolster claims that their products can improve cognitive performance and reduce the risk of dementia. Earlier this year, however, one large brain training company was fined $2 million for false advertising, and subsequently ordered by the Federal Trade Commission to reimburse 13,000 customers who paid for their brain training app.
We have learnt a great deal about the various forms of neuroplasticity over the years. Synaptic connections are trimmed and refined extensively during brain development, to tune the cells involved in sensory perception and sculpt the circuits they contribute to; the modification of synaptic connections in diffuse networks of nerve cells are essential for learning and memory; and the brain’s ability to reroute existing neural pathways, and to form entirely new ones, can enable us to recover from brain injuries and other insults, to a greater or lesser extent.
Neuroscientists agree that plasticity is an inherent property of the nervous systems of all organisms. Neuroplasticity is not, however, a miracle cure for any and every ailment – the brain is a biological system that follows the laws of physics. It has its limits, and so its ability to change itself is also limited by the same laws.
Claims about neuroplasticity should therefore be treated with scepticism. Neuroplasticity is a nebulous term, and so any claims that do not specify exactly what type of plasticity is taking place, and exactly where it is happening, is meaningless.
Moheb Costandi trained as a developmental neurobiologist and now works as a freelance writer. He writes the Neurophilosophy blog, hosted by The Guardian, and his second book, Neuroplasticity, has just been published by MIT Press.