Young brains are plastic, meaning their circuitry can be easily rewired to promote learning. By adulthood, however, the brain has lost much of its plasticity and can no longer readily recover lost function after, say, a stroke. Now scientists have successfully restored full youthful plasticity in adult mice by transplanting young neurons into their brain—curing their severe visual impairments in the process.
In a groundbreaking study published in May in Neuron, a team of neuroscientists led by Sunil Gandhi of the University of California, Irvine, transplanted embryonic mouse stem cells into the brains of other mice. The cells were primed to become inhibitory neurons, which tamp down brain activity. Prior to this study, it was widely doubted that the adult brain would allow these cells to disperse, integrate and reactivate plasticity.
The cells were integrated in the brain and caused large-scale rewiring, restoring the high-level plasticity of early development. In visually impaired mice, the transplant allowed for the restoration of normal vision, as demonstrated by tests of visual nerve signals and a swimming maze test.
The scientists have not yet tested the transplanting technique for other neurological disorders, but they believe the technique has potential for many conditions and injuries depending on how, exactly, the new neurons restore plasticity. It is not yet known whether the proliferation of the transplanted cells accounts for the restored plasticity or if the new cells trigger plasticity in existing neurons. If the latter, the treatment could spur the rewiring and healing of the brain following traumatic brain injury or stroke.
Source & further reading:http://www.scientificamerican.com/article/neuron-transplants-may-one-day-reverse-blindness/
Gif showing neurons firing in the hippocampus of a mouse
Video source for the gif:www.youtube.com/watch?v=j7aOwjGLOq0