The Marvel & Mystery of the Human Brain
June 15, 2012 § Leave a comment
Nothing is accomplished without the intention of the Mind through the service of the brain. Henceforth, it’s our noble and pleasurable duty to understand how they function. ~ (Hiram Surtyr)
Impossible as it sounds, we have more brain cell connections than there are stars in the universe. The visible universe, I mean, since 96% of the measurable universe is invisible…
Linger with that thought a moment, picturing the infinities of space – a carbon-paper night struck through with countless stars. Then picture the microscopic hubbub in one brain.
A typical brain contains about 100 billion neurons, consumes a quarter of the body’s oxygen, and spends most of the body’s calories, though it only weighs about three pounds.
A ten-watt lightbulb uses the same amount of electrical energy.
In a dot of brain no larger than a single grain of sand, 100,000 neurons go about their work at a billion synapses. In the cerebral cortex alone, 30 billion neurons meet at 60 trillion synapses a billionth of an inch wide. Only a tiny lightening-bolt-like apostrophe, and a space essential as the gap between neurons, stands between impossible and I’m possible.
Like stars in the universe, neurons don’t occupy all of the brain, most of which is water. And neurons don’t act alone. Though they are little-known players in the drama of the mind, 90% of the brain’s cells are spidery glia (Greek for “glue”). A varied crowd of cells with many jobs, from cook to bodyguard, they’re dominated by star-shaped astrocytes, which unfurl long arms and reach right into synapses, altering events. Without glia, neurons would be nothing. On their own, neurons can’t feed or sheathe themselves, avoid saboteurs, make themselves understood.
For some while, these glial cells were regarded mainly as filler, the gummy sludge holding neurons in place. But now they’re taken more seriously, not just as the neurons’ servants but possibly their handlers. A tightly packed corps, they nourish the neurons with lactate (manufactured from glucose in the blood). To protect neurons, they can flatten capillaries with the palm-like ends of their tendril arms and thus hold toxins at bay outside the brain. They can clean up spills of glutamate, the vital neurotransmitter that’s nonetheless poisonous in excess (it’s implicated in stroke and Alzheimer’s, for example, and contributes to the headache from MSG in Chinese cuisine).
But glia are also manipulative cells that can converse among themselves, listen to neurons, voice their own concerns, and ultimately influence what neurons say. They may prompt neurons to create more synapses, rouse sleepy neurons and put them to work, and order neurons to strengthen or weaken their best contacts. They may be vital to memory and learning. Glia with many faces and jobs touch neurons, profoundly altering their fate. Coexisting, as they must, both neurons and glia are dependable, dependent, full of talk and back talk, central to the brain’s social fabric and perpetual hum.
~ excerpt from chapter 7 of “An Alchemy of Mind: The Marvel & Mystery of the Brain” by Diane Ackerman, Ph. D. ~