The human brain is incredibly adaptive. Our mental capacity is astonishingly large, and our ability to process widely varied information and complex new experiences with relative ease can often be surprising. The brain’s ability to act and react in ever-changing ways is known, in the scientific community, as “neuroplasticity.” This special characteristic allows the brain’s estimated 100 billion nerve cells, also called neurons (aka “gray matter”), to constantly lay down new pathways for neural communication and to rearrange existing ones throughout life, thereby aiding the processes of learning, memory, and adaptation through experience. Without the ability to make such functional changes, our brains would not be able to memorize a new fact or master a new skill, form a new memory or adjust to a new environment; we, as individuals, would not be able to recover from brain injuries or overcome cognitive disabilities. Because of the brain’s neuroplasticity, old dogs, so to speak, regularly learn new tricks of every conceivable kind.
Plasticity Happens Wherever Neuro-processing Occurs While genetics certainly play a role in establishing the brain’s plasticity, the environment also exerts heavy influence in maintaining it. Take, for example, the newborn’s brain, which every day is flooded with new information. When the infant body receives input through its many different sensory organs, neurons are responsible for sending that input back to the part of the brain best equipped to handle it – and this requires each neuron to “know” something about the proper neural pathways through which to send its bits and pieces of information. To make this mental roadmap work, each neuron develops an axon to send information to other brain cells via electrical impulses, and also develops many dendrites that connect it to other neurons so that it can receive information from them. Each point of connection between two neurons is termed a “ synapse.” Our genes have, at birth, laid down the basic directions for neurons to follow along this roadmap, and have built its major “highways” between the basic functional areas of the brain. Environmental influence then plays the key role in forging a much denser, more complex network of interconnections. These smaller avenues and side roads, always under construction, can make the transfer of information between neurons more efficient and rich with situation-specific detail. This is clearly evidenced by the rapid increase in synaptic density that can be seen in a normally developing human. Genetics form a neural framework that, at birth, starts each neuron off with roughly 2,500 connections. By age two or three, however, sensory stimulation and environmental experience have taken full advantage of the brain’s plasticity; each neuron now boasts around 15,000 synapses. This number will have declined somewhat by the time we enter adulthood, as many of the more ineffective or rarely used connections – formed during the early years, when neuroplasticity is at its peak — are done away with.
While genetics certainly play a role in establishing the brain’s plasticity, the environment also exerts heavy influence in maintaining it. Take, for example, the newborn’s brain, which every day is flooded with new information. When the infant body receives input through its many different sensory organs, neurons are responsible for sending that input back to the part of the brain best equipped to handle it – and this requires each neuron to “know” something about the proper neural pathways through which to send its bits and pieces of information. To make this mental roadmap work, each neuron develops an axon to send information to other brain cells via electrical impulses, and also develops many dendrites that connect it to other neurons so that it can receive information from them. Each point of connection between two neurons is termed a “ synapse.” Our genes have, at birth, laid down the basic directions for neurons to follow along this roadmap, and have built its major “highways” between the basic functional areas of the brain. Environmental influence then plays the key role in forging a much denser, more complex network of interconnections. These smaller avenues and side roads, always under construction, can make the transfer of information between neurons more efficient and rich with situation-specific detail. This is clearly evidenced by the rapid increase in synaptic density that can be seen in a normally developing human. Genetics form a neural framework that, at birth, starts each neuron off with roughly 2,500 connections. By age two or three, however, sensory stimulation and environmental experience have taken full advantage of the brain’s plasticity; each neuron now boasts around 15,000 synapses. This number will have declined somewhat by the time we enter adulthood, as many of the more ineffective or rarely used connections – formed during the early years, when neuroplasticity is at its peak — are done away with.
Neuroplasticity can work in two directions; it is responsible for deleting old connections as frequently as it enables the creation of new ones. Through this process, called “synaptic pruning,” connections that are inefficient or infrequently used are allowed to fade away, while neurons that are highly routed with information will be preserved, strengthened, made even more synaptically dense. Closely tied in with the pruning process, then, is our ability to learn and to remember. While each neuron acts independently, learning new skills may require large collections of neurons to be active simultaneously to process neural information; the more neurons activated, the better we learn.