Neuroscientists Say Textbook Brain 'Rewiring' Theory Is ' Wrong' about the exception of miracles?

Story by Robyn White?

The brain cannot rewire itself—such as following a loss of sight, an amputation, or a stroke—as is commonly claimed, scientists have said.

The team notes that scientific textbooks often state that the brain can repurpose parts of itself for new functions. For example, many believe that when a person loses sight, the brain can rewire the visual cortex to process sounds—offering a form of "echolocation" for navigating.

Another commonly held belief is that following a stroke, when an individual is initially unable to move their limbs, the brain repurposes parts of itself, allowing regained control.

An international team of scientists, however, are still determining. The idea that the brain can rewire itself in response to an injury or medical condition is "fundamentally flawed," Professors Tamar Makin of the?University of Cambridge , England, and John Krakauer of Johns Hopkins University argue in?the journal?eLife.

They propose that the brain is simply retraining itself to use previously latent abilities.

"The idea that our brain has an amazing ability to rewire and reorganize itself is appealing. It gives us hope and fascination, especially when we hear extraordinary stories of blind individuals developing almost superhuman echolocation abilities, for example, or stroke survivors miraculously regaining motor abilities they thought they'd lost," said Krakauer.

"This idea goes beyond simple adaptation or plasticity, implying a wholesale repurposing of brain regions. But while these stories may well be true, the explanation of what is happening is, in fact, wrong."

Previous studies show that the brain can adapt. However, Makin and Krakauer argue that it needs to create new functions, as suggested before. They reported that the areas being utilized were present since birth and were not newly adapted.

For example, one study from the 1980s analyzed what happens to the body following a finger amputation. The researchers reported that the attention the brain previously gave the finger was reallocated after it was removed. The team argued that this showed how the brain rewired in response to this change.

However, Makin had previously found evidence in a study from 2022 that this might not be the case. She used nerve blockers to temporarily mimic the effect of amputating a forefinger. Makin found that before amputation, signals from neighboring fingers mapped into the brain region were said to be "responsible" for the forefinger.

This suggests that while this brain region might have been primarily involved in processing signals from the forefingers, it was not doing this exclusively. Following the simulated amputation, existing signals from the other fingers are just being increased.

"The brain's ability to adapt to injury isn't about commandeering new brain regions for entirely different purposes," Makin said.

"These regions don't start processing entirely new types of information. Information about the other fingers was available in the examined brain area even before the amputation; it's just that in the original studies, the researchers didn't pay much attention to it because it was weaker than for the finger about to be amputated."

By examining these other studies alongside their research, Makin and Krakauer concluded that there is no evidence to suggest that these widely held notions are correct. As they noted, there has been no evidence to suggest that those born blind or those who suffer a stroke ever develop new abilities due to brain rewiring.

"This learning process is a testament to the brain's remarkable—but constrained—capacity for plasticity," Makin said. "There are no shortcuts or fast tracks in this journey.