Researchers from the Picower Institute for Learning and Memory at MIT have recently found that contrary to popular belief, neurons do grow in mature brains. It had been widely accepted that structural remodeling of neurons does not occur in adult brains, but the discovery that it does could lead to advances in treatments of spinal cord injuries and other neural damage caused by accidents or disease. The study, co-authored by Elly Nedivi, appears in the December 27th issue of Public Library of Science (PLoS) Biology.
“Knowing that neurons are able to grow in the adult brain gives us a chance to enhance the process and explore under what conditions — genetic, sensory or other — we can make that happen,” said Nedivi.
For several weeks the scientists studied the neurons in the visual cortices of living mice using a method known as two-photon imaging. The two dimensional images were assembled into the first three dimensional representations of adult cortical neurons.
What the researchers witnessed while watching the 3-D images over time was not only a surprise, but it also brought them to the realization that scientists hoping to spur neural growth to treat spinal cord injuries may be focusing on the wrong part of the cell. Instead of working to regenerate the axon, the long slender projection that conducts electrical impulses away from the neuron, Nedivi’s work indicates that the dendrites, the branched projections that conduct the electrical stimulation received from other neurons, may play a more significant role in neural plasticity.
The time-lapse images revealed that the dendrite structures were changing more than anyone ever thought. Some would grow and interact with neighboring neurons, while others would retract. The change in length was not always large, nor was the rate constant. Most times dendrite length would only change by a few microns, and sometimes nothing happened for several weeks at a time. But the fact that there were any changes at all is significant.
As Nedivi puts it, “The scale of change is much smaller than what goes on during the critical period of development, but the fact that it goes on at all is earth-shattering.”
Read the MIT press release: “Picower researcher finds neuron growth in adult brain“