By enabling the rigid brains of adult mice to return to the high levels of plasticity found in juvenile brains, scientists are opening new pathways to the treatment of brain injuries such as stroke. Back in 2013, researchers from Yale University reported the discovery of a molecular switch that achieved this result, and now scientists at the University of California, Irvine, have managed to make an old brain young again using a different approach.

The UC Irvine technique involved transplanting a type of embryonic neuron into the brains of adult mice. After transplantation, these neurons expressed GABA (gamma-Aminobutyric acid), a chief inhibitory neurotransmitter in the mammalian central nervous system that aids in motor control, vision and numerous other cortical functions.

This resulted in a return to youthful plasticity in the mouse's adult brain that allowed rapid and robust changes in neural pathways and synapses in response to learning and experience.

Like the Yale team, the UC Irvine researchers say their technique could be used to accelerate rehabilitation following brain injuries, but added the research could lead to new treatments for developmental brain disorders, such as autism and schizophrenia, as well as therapies for currently incurable brain disorders.

Demonstrating the potential for future clinical applications for GABA neuron transplantation, the researchers also used it to restore normal sight to adult mice with amblyopia, or lazy eye. Amblyopia is a long-lasting visual deficit that results when visual stimulation is transmitted through the optic nerve to the brain poorly, or not at all, for an unbroken period of time. In an attempt to correct the problem, UC Irvine neurobiologist Sunil Gandhi and his colleagues transplanted the GABA-expressing neurons into the visual cortex of adult mice with the condition.

"Several weeks after transplantation, when the donor animal’s visual system would be going through its critical period, the amblyopic mice started to see with normal visual acuity," said Melissa Davis, a postdoctoral fellow and lead author of the study.

The team also believes that such research could help shed light on the basic mechanisms responsible for "critical periods" of brain development.

Their research appears in the journal Neuron.

Source: UC Irvine