Our ability to learn new information and adapt to changes in our daily environment, as well as to retain lifelong memories, appears to lie in the minute junctions where nerve cells communicate, according to a new study by NYU Langone Medicine Center researchers. The study is published online this week in the journal Nature.
The scientists, led by Wen-Biao Gan, PhD, associate professor of physiology and neuroscience at NYU School of Medicine, discovered that a delicate balancing act occurs in the brain where neuronal connections are continually being formed, eliminated, and maintained. This feat allows the brain to integrate new information without jeopardizing already established memories, the new study suggests.
Using a powerful optical imaging technique called two-photon microscopy, Dr. Gan and colleagues at The Helen and Martin Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, viewed the precise changes that take place at synapses, the junctions where nerve cells communicate, in the wake of learning a new task or being exposed to a novel situation. New knowledge, explains Dr. Gan, prompts alterations in the dendritic spines, the knobby protrusions along the branching ends of nerve cells. With learning, spines are gained and others lost.
"We've known for a long time that the brain remodels after learning," says Dr. Gan "Our studies show that the brain does this in two ways: by adding a tiny fraction of new connections to the brain's neural circuitry and eliminating old ones."
Dr. Gan and his associates tracked changes in the brains of mice before and after experiencing a new stimulus (a string of beads hung at different places along the cage) or learning a new task (running on an accelerated spinning wheel). To open a window to the brain, the team shaved away the skull over the animals' cortex in which the nerve dendrites were lit up by fluorescent proteins. Then, using
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NYU Langone Medical Center / New York University School of Medicine