The Axolotl Can Rebuild Its Own Brain — Here Is How Scientists Think It Works
If you have ever seen an axolotl, you probably remember it. This small aquatic salamander has bushy pink gills fanning out from its head, wide cartoon-like eyes, and an expression that looks like a permanent grin. It almost seems too cheerful to be a serious scientific subject. But the axolotl — known scientifically as Ambystoma mexicanum — is at the center of some of the most exciting brain research happening right now, because it can do something virtually no other vertebrate on Earth can do: regrow parts of its own brain after injury.
For scientists who study the nervous system, this is a genuinely big deal. The brain and spinal cord are considered the most fragile parts of the vertebrate body. In humans and other mammals, serious brain injuries are usually permanent. One of the main reasons for this is that when a mammal's brain is damaged, the body's first response is to form a kind of internal wall called a glial scar. Think of it like emergency caution tape around a construction zone — it stops further damage from spreading, but it also blocks any new growth from getting through. The axolotl's brain, remarkably, does not form this kind of scar. Instead of walling off the injury, it leaves the area open and ready for reconstruction.
According to a 2013 study published in the journal Neural Development, the rebuilding process in axolotls follows a careful step-by-step sequence. Once the wound closes, special cells lining the inside of the brain's fluid-filled chambers — called ependymoglial cells — become activated. Under normal conditions, these cells just sit quietly and do very little. After an injury, though, they wake up and start dividing rapidly, producing large numbers of new cells. Those new cells then migrate toward the damaged area and gradually transform into the specific types of neurons, or brain cells, that were lost. Over weeks, the regenerating neurons even begin reconnecting with each other, forming new communication pathways. The end result is a region of brain tissue that closely resembles the original structure.
So why can the axolotl do this when humans cannot? Part of the answer comes down to how the axolotl's cells behave after injury. In mammals, most mature cells are locked into their identity — a brain cell stays a brain cell, a skin cell stays a skin cell. But axolotl cells near a wound can partially reverse that process, becoming more flexible and capable of producing different cell types again. It is a bit like taking a finished sculpture and softening the clay back to a workable state. Scientists call this quality cellular plasticity. Mammals have largely lost this flexibility because uncontrolled cell growth is dangerous — it can cause cancer or disrupt delicate, stable brain circuits. The axolotl somehow manages to reactivate this flexibility safely, which is one of the things that makes it so scientifically fascinating.
Another key factor is the axolotl's lifestyle. It is an aquatic animal with a slow metabolism, meaning its body runs at a lower energy level than a warm-blooded mammal. A lengthy, weeks-long repair process is biologically affordable for an animal that moves slowly and does not burn through energy quickly. On top of that, the axolotl's brain is organized in a way that allows undamaged regions to keep handling essential tasks — like swimming, feeding, and responding to its environment — while the injured area is under reconstruction. The brain is never entirely offline.
Interestingly, scientists believe that axolotls did not necessarily invent this ability from scratch. A 2009 review in Nature Reviews Neuroscience suggested that regeneration may actually be an ancient trait that many vertebrates — including early ancestors of mammals — once shared. Over millions of years of evolution, mammals traded much of this regenerative ability for faster healing, stronger immune responses, and more stable brain circuits. Salamanders like the axolotl appear to have held on to far more of that ancient toolkit. For researchers hoping to one day help people recover from brain injuries or spinal cord damage, the axolotl's biology offers a remarkable glimpse at what the nervous system might be capable of — if only we understood it well enough to unlock it.
Source: Forbes