Читать книгу Brain Fitness for Women - Sondra Kornblatt - Страница 11

The field of neuroscience is now being compared with astronomy, because they both deal with unknowns of similar magnitude. You know how you feel the infinite expanse of the universe when you see a thick carpet of stars in a dark sky? That magnitude is echoed in our brains, which hold hundreds of trillions of synapses—1,500 times the number of stars that fill the Milky Way galaxy.

Our brains have hundreds of trillions of synapses—1,500 times the number of stars in the Milky Way galaxy.

Information travels quickly in our brains—very quickly. The slowest speed that information is transferred between neurons is 260 mph. That's slightly faster than the speed of the original Bugatti EB, one of the fastest road-legal cars in the world, clocked at 253 mph.

Our brains are not only fast, but also busy. One human brain has an average of 70,000 thoughts per day and generates more electrical impulses than all the telephones in the world combined.

The most obvious magical marvels that do all this work are called neurons, the primary cells of our brain and nervous system. About 100 billion neurons live under your skull in your three-pound spongy ball of brilliance. Each neuron looks like a spindly tree drawn by Dr. Seuss and consists of three parts:

 Dendrites, branches that receive input from other neurons,

 Cell body, which sustains the life of the cell and contains its DNA,

 Axon, a living cable that carries electrical impulses at very high speeds toward the dendrites of neighboring neurons.

A synapse is a junction between the axon of one neuron and the dendrite of another (or it can be between a neuron and a muscle). A synapse sends electrical or chemical (such as neurotransmitter) signals, which either excite or inhibit the chance for action. Each connection creates a weak electromagnetic field that can join together with the electromagnetic fields of other neural connections. Those combined connections increase the speed, empathy, and activity between neurons that are not in direct contact.⁵

The glia, or support cells for your neurons, are part of this electromagnetic “telepathy” of the brain. Glial cells are far more numerous than neurons, making up 90% of your brain's cells. They consume parts of dead neurons, manufacture myelin (a white neuron coating that protects the axon and increases axon impulses up to fifty times⁶), form an immune system,⁷ provide physical and nutritional support for neurons, and even communicate with other synapses.⁸

Science is learning more about glial cells, adding to knowledge about neurons. Half of glial cells are tiny granule cells, which hang out in the cerebellum. While the cerebellum (remember it's the “little brain” of dough squeezed out the back of your wrist) makes up only about 10% of the brain, it contains more nerve cells than all the rest of the brain combined and is one of the brain's most rapidly acting mechanisms.⁹ It connects to the highest level of the brain, the cerebral cortex, via 40 million nerve fibers. Compare that to your optic track, which uses just 1 million to take care of seeing and reading.

The cerebral cortex is our gray matter, composing about 85% of the brain; it contains the lobes (frontal, parietal, temporal, and occipital). The densely packed neurons in the cerebral cortex work together to create neural networks, pathways of learning that constantly communicate and change.¹⁰