We hear a lot about neuroplasticity, — the way the brain compensates for absences or injuries. A recent neuroscience paper offers a look at what the brain is really doing in such cases.
One area that has attracted a lot of attention is human echolocation, the ability of a person who is blind — due to damage to the visual cortex of the brain — to use a form of echolocation to sense objects that cannot actually be seen.
Professors Tamar Makin (Cambridge) and John Krakauer (Johns Hopkins) propose that what happens in the brain is something like this:
In their article, Makin and Krakauer look at a ten seminal studies that purport to show the brain’s ability to reorganise. They argue, however, that while the studies do indeed show the brain’s ability to adapt to change, it is not creating new functions in previously unrelated areas – instead it’s utilising latent capacities that have been present since birth…
Makin and Krakauer do not dismiss the stories of blind people being able to navigate purely based on hearing, or individuals who have experienced a stroke regain their motor functions, for example. They argue instead that rather than completely repurposing regions for new tasks, the brain is enhancing or modifying its pre-existing architecture – and it is doing this through repetition and learning.Craig Brierley, “Our brains are not able to ‘rewire’ themselves, despite what most scientists believe, new study argues,” University of Cambridge, November 21, 2023
The distinction may not seem crucial to most of us; after all, if a fix works, it works. But Makin and Krakauer wish to caution that the brain’s complexity offers no easy fix: “So many times, the brain’s ability to rewire has been described as ‘miraculous’ – but we’re scientists, we don’t believe in magic. These amazing behaviours that we see are rooted in hard work, repetition and training, not the magical reassignment of the brain’s resources.”
And yet there are people walking around with split brains, half a brain, a very compressed brain, a missing temporal lobe, or a missing cerebellum. In many cases, the deficit is discovered accidentally, while attempting to diagnose a comparatively minor problem. The remarkable thing is not that considerable effort is required to overcome the disadvantages of brain damage or absence as that it can be done at all.
The brain’s plasticity is not magic but it is remarkable anyway. In fact, it’s worth asking, how much of the adaptation is driven, not by the brain alone but by the restless mind?
The paper, Tamar R Makin, John W Krakauer (2023) Against cortical reorganisation eLife 12:e84716., is open access.
You may also wish to read: How can a woman missing her olfactory bulbs still smell? The brain’s plasticity intrigues and puzzles researcher, and it also raises a larger issue. If the mind is merely what the brain does, as many materialist pundits claim, what is the mind when the brain … doesn’t? At times, the mind appears to be picking up where the brain left off.