Neuroplasticity, also known as neural plasticity, or brain plasticity, is the ability of neural networks in the brain to change through growth and reorganization. It is when the brain is rewired to function in some way that differs from how it previously functioned. These changes range from individual neuron pathways making new connections, to systematic adjustments like cortical remapping. Examples of neuroplasticity include circuit and network changes that result from learning a new ability, environmental influences, practice, and psychological stress. Neuroplasticity was once thought by neuroscientists to manifest only during childhood, but research in the latter half of the 20th century showed that many aspects of the brain can be altered (or are "plastic") even through adulthood. However, the developing brain exhibits a higher degree of plasticity than the adult brain. Activity-dependent plasticity can have significant implications for healthy development, learning, memory, and recovery from brain damage. History Origin The term plasticity was first applied to behavior in 1890 by William James in The Principles of Psychology. The first person to use the term neural plasticity appears to have been the Polish neuroscientist Jerzy Konorski. One of the first experiments providing evidence for the neuroplasticity phenomenon was conducted in 1793 by Italian anatomist Michele Vicenzo Malacarne who described experiments in which he paired animals, trained one of the pair extensively for years, and then dissected both. Malacarne discovered that the cerebellums of the trained animals were substantially larger than the cerebellum of the untrained animals. However, while these findings were significant, they were eventually forgotten. In 1890, the idea that the brain and its function are not fixed throughout adulthood was proposed by William James in The Principles of Psychology, though the idea was largely neglected. Up until the 1970s, neuroscientists believed that the brain's structure and function was essentially fixed throughout adulthood. While the brain was commonly understood as a nonrenewable organ in the early 1900s, Santiago Ramón y Cajal, father of neuroscience, used the term neuronal plasticity to describe nonpathological changes in the structure of adult brains. Based on his renowned neuron doctrine, Cajal first described the neuron as the fundamental unit of the nervous system that later served as an essential foundation to develop the concept of neural plasticity. He used the term plasticity in reference to his work on findings of degeneration and regeneration in the central nervous system after a person had reached adulthood, specifically.