Glia: The brain's not-so-silent majority

Neuroglia (Public Domain)

The brain as a governing organ is said to have its own version of a silent majority.  That would be the glial cells, otherwise known as "neuroglia" or just plain "glia."

"Glia," which means "glue" in Greek, are far more complicated than their name implies.  They don't just stick around holding neurons in place, but also supply them with vital oxygen and nutrients.  These powerhouse cells also insulate one neuron from the other, destroy threatening organisms, dispose of dead

neurons, undergo cell division within adulthood and promote the repair of certain neurons (which could bode well for future breakthroughs in regeneration after nervous-system injuries), and even modulate neurotransmission (in a way that is not yet clearly fathomed).

Although these functions certainly don't seem so "silent," glia nevertheless comprise the majority of central and peripheral nervous system cells.  Wikipedia reports that "neuroglial cells are generally smaller than  neurons and outnumber them by five to ten times" - thus comprising "about half the total volume of the brain and spinal cord."  The glia/neuron ratio varies, depending upon brain size (the larger the brain, the higher the glia/neuron ratio; e.g., a mouse's brain is only 65% glia, whereas a human's brain is 90% glia)–and depending

upon which area of the nervous system the glia are located in (e.g., the cerebral cortex glia/neuron ratio is 3.72, whereas the ratio "of the basal ganglia, diencephalon and brainstem combined is 11.35").

Just as with the Greek concept "psyche" (which The Free Dictionary not only defines as "the human faculty for thought, judgment and emotion…"  – but also as "the soul or self"), what we do know about this mysterious "glue" is probably far less than what we don't.

Resources

http://en.wikipedia.org/wiki/Neuroglia

Copyright January 14, 2013 by Linda Van Slyke   All Rights Reserved