New research from Professors Tamar Makin and John Krakauer challenges the commonly held belief that the brain can rewire itself to compensate for sensory loss such as blindness or stroke. Their analysis of groundbreaking research shows that the brain does not create new functions in previously unrelated areas, but rather strengthens pre-existing structures through learning and repetition. This awareness is critical to setting realistic recovery expectations and understanding the effort behind the recovery story.

Contrary to popular belief, the brain does not have the ability to rewire itself to compensate for blindness, amputation or stroke-related damage, say scientists from the University of Cambridge and Johns Hopkins University.

In a recent paper published in eLife, Professors Tamar Makin and John Krakauer of the University of Cambridge argue that the idea that the brain can reorganize itself in response to injury or defect and repurpose specific areas for new functions is fundamentally flawed, although often cited in scientific textbooks. Instead, they believe that what is happening is that the brain is being trained to take advantage of already existing but latent abilities.

Misconceptions about brain plasticity

One of the most common examples is when a person loses their sight - or is born blind - and the visual cortex that was previously dedicated to vision is rewired to process sound, allowing the person to use a form of "echolocation" to navigate a cluttered room. Another common example is that stroke patients are initially unable to move a limb, but they can repurpose other areas of the brain to regain control.

"The idea that our brains have this amazing ability to restructure and reorganize itself is attractive," said Krakauer, director of the Center for Motor Learning and Brain Repair Research at Johns Hopkins University. "It brings us hope and fascination, especially when we hear about blind people developing almost superhuman echolocation abilities, or There are extraordinary stories of stroke survivors miraculously regaining motor abilities they thought they had lost. This idea goes beyond simple adaptation or plasticity - it implies a wholesale repurposing of brain areas. But while these stories may well be true, the explanation for what is happening is actually wrong."

Reassessing classic research

In the article, Makin and Krakauer review ten seminal studies designed to demonstrate the brain's ability to reorganize. However, they argue that while these studies show the brain's ability to adapt to change, the brain is not creating new functions in previously unrelated areas, but rather exploiting latent abilities that have been present since birth.

For example, one of the studies - conducted in the 1980s by Professor Michael Melzenich of the University of California, San Francisco - looked at what happens when a hand loses a finger. The hand has a specific representation in the brain, and each finger seems to map to a specific brain area. Melzenich believes that by removing the index finger, areas of the brain previously assigned to that finger are reallocated to processing signals from neighboring fingers—in other words, the brain rewires itself in response to changes in sensory input.

Makin says that's not the case, and his own research offers another explanation.

Challenge the Reload Theory

In a study published in 2022, Makin used a nerve-blocking agent to temporarily simulate the effects of amputating a subject's index finger. Her research shows that even before amputation, signals from neighboring fingers map to the area of ​​the brain "responsible" for the index finger—in other words, while this brain area may be primarily responsible for processing signals from the index finger, that's not entirely true. After amputation, existing signals from other fingers are "dial-in" in this brain area.

Makin, from the Medical Research Council (MRC) Cognitive and Brain Sciences Research Unit at the University of Cambridge, said: "The brain adapts to injury in the same way that the index and middle fingers do, by recruiting new brain areas for completely different purposes. These areas don't start processing entirely new types of information. Even before the amputation, the brain areas examined had information about other fingers, but in the original study the researchers didn't pay much attention to this information because it was weaker than the finger about to be amputated."

Evidence from congenitally deaf cats

In congenitally deaf cats, the auditory cortex - the area of ​​the brain that processes sound - appears to be repurposed for processing vision. But when they were implanted with cochlear implants, this brain area immediately started processing sound again, suggesting that the brain wasn't actually rewiring.

Looking at other studies, Makin and Krakauer found no convincing evidence that the visual cortex of people born blind or the uninjured cortex of stroke survivors ever developed a new functional ability that was not otherwise present.

Understanding true brain plasticity

Makin and Krakauer do not dismiss stories of blind people navigating purely by hearing or stroke victims regaining motor function. Instead, they believe that the brain does not entirely reallocate areas for new tasks, but rather strengthens or modifies existing structures through repetition and learning.

They argue that understanding the true nature and limitations of brain plasticity is critical, both to set realistic expectations for patients and to guide clinicians in their approach to rehabilitation.

Makin added: "This learning process is a testament to the brain's extraordinary plasticity, but this plasticity is also limited. There are no shortcuts or fast lanes in this process. The idea of ​​quickly unlocking the brain's hidden potential or tapping vast unused reserves is more wishful thinking than reality. It is a slow, gradual process that requires persistent effort and practice. Recognizing this helps us understand the hardship behind every recovery story and adjust our strategies accordingly."

"Too often, the brain's ability to rewire is described as a 'miracle' - but we are scientists and we don't believe in magic. These amazing behaviors we see result from hard work, repetition and training, not a magical reallocation of brain resources."