Our brain is a thinking organ that learns and grows by interacting with the world through perception and action. Mental stimulus improves brain function and actually protects against cognitive decline, as the same with physical exercise.
The human brain is constantly adapting and rewiring itself. Even in old age, the brain can still grow new neurons. Severe mental decline is usually caused by disease, whereas most age-related losses in memory or motor skills simply result from inactivity and a lack of mental exercise and stimulation. Simply put: use it or lose it.
In the beginning
Commencing in the womb and throughout life this immense network continues to expand, adapt, and learn. The primary need for a nervous system was to coordinate movement, so an organism could go find food, instead of waiting for the food to come to it. Jellyfish and sea anemone were the first animals to create nerve cells, they had a great advantage over the sponges that waited brainlessly for food to arrive. After millions of generations of trail and error, nervous systems evolved some remarkable ways of going out to eat. But behind all the numerous forms of life today, the primary directive remains. Movement is in fact a good measure of aging. Inflexibility signals weakness, sickness or death, while a flexible body and fluid mind are the characteristics of youth.
Before birth, the brain creates neurons and the brain cells that communicate with each other at the rate of 15 million firings per hour. When the baby is born, about 100 billion neurons were in position to organize themselves in response to the new environment, no matter the culture, climate, language, or lifestyle.
During infancy, billions of these remarkable cells intertwined into the extensive networks that integrated the nervous system. By the time a person reaches four or five years old, fundamental cerebral architecture will be complete. Until the age of early teens, it is considered the window of opportunity, as this is the time where the brain absorbs the most. Easily to learn language and writing, math and music, as well as the coordinated movements used in sports and dance. But, at any age we can and should continue to build our brain and expand our mind.
Throughout life, neural networks reorganize and reinforce themselves in response to new stimuli and learning experiences. This body-mind interaction is what stimulates brain cells to grow and connect with each other in complex ways. They do so by extending branches of intricate nerve fibers called dendrites (from the Latin word for "tree"). These are the antennas through which neurons receive communication from each other.
A healthy, well-functioning neuron can be directly linked to tens of thousands of other neurons, creating a totality of more than a hundred trillion connections, each capable of performing 200 calculations per second. This is the structural basis of your brain's memory capacity and thinking ability.
Neuroscientists believe that learning and memory involve changes at the neuron-to-neuron synapses. Such changes are called long-term potentiation (LTP), making it easier for connected neurons to communicate with each other and therefore to form memories. LTP involves patterns of synaptic strengthening and weakening that can last for weeks. Because receptor aggregation may contribute to LTP and scattering may be a factor to the reverse scenario, such as long-term depression. The discovery that receptors can scurry in and out of synapses strengthens the synaptic hypothesis of learning.
A study by neuroscientists at Brown University provided further evidence that learning uses long-term potentiation LTP to produce changes in the synaptic connections between brain cells that are necessary to acquire and store new information. When the researchers taught rats a new motor skill, scientists found that the animals' brains had also changed. The strength of synapses between neurons in the motor cortex of their brains had increased through a process consistent with the use of LTP. Previously, "the link between LTP, synaptic modification and learning was tentative," said senior author John Donoghue, professor of neuroscience. "This latest study provides strong evidence that learning itself engages LTP in the cerebral cortex as a way to strengthen synaptic connections."
Mind and body relationship
Brain chemistry reveals a crucial unity of mind and body. Neurons not only contact other neurons, they also connect with skeletal muscles, at a specialized structure called the neuromuscular junction. There the brain uses acetylcholine where its primary chemical neurotransmitter for memory and attention is to communicate with muscles. Another of the brain's key chemical messengers, dopamine, helps regulate fine motor movement.
The role of these neurotransmitters in regulating movement underscores the close relation between body and mind, muscle and memory. In fact, many masseuses find that deep massage can trigger the release and awareness of powerful, long-held emotional memories.
When acetylcholine is released at a neuromuscular junction, it crosses the tiny space (synapse) that separates the nerve from the muscle. It then binds to acetylcholine receptor molecules on the muscle fiber's surface. This initiates a chain of events that lead to muscle contraction.
Scientists have shown that muscle fiber contains a scaffold made of special proteins that hold these acetylcholine receptors in place. Research led by Jeff W. Lichtman, M.D., Ph.D., at Washington University School of Medicine in St. Louis, indicates that a loss of nerve signals due to inactivity actually separates this scaffold and causes a loss of acetylcholine receptors. When the muscle becomes active again, however, the scaffold tightens its grip and grasps any receptors that come by.
"So muscle activity is a cue to keep a synapse stable, and synaptic inactivity is a cue to disassemble a synapse," says Lichtman, a professor of neurobiology. "So if you lose activity, you lose receptors. But if you regain activity, you get those receptors back."