A team of scientists has cured a brain disorder in adult mice by rebooting the rodents' brains and allowing them to rewire themselves.
The research demonstrates that certain features of young brains can be recreated in mature brains, even in parts of older brains that scientists believed were impervious to change.
It could also pave the way for treating a variety of developmental disorders that begin relatively early in life.
In the early years of life, brains in animals are malleable. The cells in the brains begin making connections at early ages and strengthen those connections throughout life. Those early stages where the brain is rapidly making connections among cells are called critical periods.
The brain continues to change throughout life, but it grows more and more difficult to break certain kinds of connections as time passes. That means it becomes harder for the brain to undo problems it may have undergone early in its development.
But Sunil Gandhi and his colleagues at the University of California, Irvine, have found a way to hit the reset button in certain regions of the brain even later in life, allowing the organ to rewire itself and iron out the kinks that can lead to disorders. (Tweet This)
In their study, the scientists implanted special cells into the brains of adult mice that suffered from a disease called amblyopia, sometimes called lazy eye.
Amblyopia is not a problem with the eye itself, but usually results instead from a problem in the connection between the eye and the brain.
The cells that Gandhi's team implanted in the mice emit a chemical called GABA, which is found in many places in the brain. GABA is an "inhibitory neurotransmitter." It prevents certain parts of the brain from becoming overexcited and causing dysfunction. Scientists have connected deficiencies in those inhibitory neurons not only to amblyopia but also to disorders such as autism and schizophrenia.
The GABA-emitting cells Gandhi and his team implanted in the mice spread throughout a section of the brain and hooked into its circuitry, essentially creating a new critical period that allowed the brain to rewire itself and cure the mice of their disorder.
"I have to say it was mind blowing," Gandhi said. "I began these experiments with colleagues about eight years ago, and all throughout we were subject to concern that this enterprise we were engaged in was far fetched."
The results were surprising in part because the implants were placed in a region of the brain called the neocortex, where scientists have never observed new cells to grow in adult brains. They therefore believed that the region would be would be a hostile environment for implanted cells.
"The neuroscientist has a default expectation that it is not possible to wire in [to the neocortex] like that," Gandhi said. "It's kind of like a Black Swan phenomenon, that now that we have the evidence, a lot of people will treat it as obvious, but I can tell you that there is a long list of my senior colleagues that thought this was impossible."
Gandhi said the process could become a powerful investigative tool for understanding how some disorders work in the brain, and could help create therapies for epilepsy, schizophrenia and autism. It could also assist with conditions such as pain from spinal cord injury or stroke recovery.
"With all potential therapies involving placing cells in the brain, one has to be very cautious," Gandhi said. "But what we hope is that this study, along with many others, begins to open the door to the therapeutic viability of cell-based approaches."