Brains, astrocytes and octopuses

From Scientific American, about brain cells called glia, that could well be more important to thought than neurons.

http://www.scientificamerican.com/article.cfm?id=the-root-of-thought-what&sc=DD_20091027

My comment follows.

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The Root of Thought: What Do Glial Cells Do?
Nearly 90 percent of the brain is composed of glial cells, not neurons. Andrew Koob argues that these overlooked cells just might be the source of the imagination

[...]

LEHRER: Could you describe some of the early experiments that first led scientists to reconsider the role of glial cells?

KOOB: Glial experiments didn't get going until the 1960s. All scientists knew about glia was that if you put neurons in petri dish, you had to have glia, or neurons would die. Then, Stephen W. Kuffler at Harvard, for reasons unknown, decided to test Pedro's accepted theory of insulation. This was around same time that cell counts in the brain revealed glial cells to be nearly 90% of the brain (this is where the neuron based idea that we only use 10% of our brain comes from). Kuffler is notable because he ironically established the Harvard 'neuro' biology department while he was performing these groundbreaking glial experiments. Anyway, Kuffler took astrocytes from the leech and mud puppy and added potassium, something that is known to flow out of neurons after they are stimulated. He thought this would confirm Pedro's theory that glial cells were insulators. What he found instead was that the electrical potential of glial cells responded to potassium. Kuffler and colleagues found that astrocytes exhibited an electrical potential, much like neurons. They also discovered in the frog and the leech that astrocytes were influenced by neuronal ion exchange, a process long held to be the chemical counterpart to thought. Since then many researchers have completed experiments on the communicatory ability of glial cells with neurons, including in the late 80s and early 90s when it was discovered glial cells respond to and release 'neuro' transmitters.

LEHRER: Why are calcium waves important?

KOOB: In short, calcium waves are how astrocytes communicate to themselves. Astrocytes have hundreds of 'endfeet' spreading out from their body. They look like mini octopi, and they link these endfeet with blood vessels, other astrocytes and neuronal synapses. Calcium is released from internal stores in astrocytes as they are stimulated, then calcium travels through their endfeet to other astrocytes. The term 'calcium waves' describes the calcium release and exchange between astrocytes and between astrocytes and neurons. Scientists at Yale, most notably Ann H. Cornell-Bell and Steven Finkbeiner, have shown that calcium waves can spread from the point of stimulation of one astrocyte to all other astrocytes in an area hundreds of times the size of the original astrocyte. Furthermore, calcium waves can also cause neurons to fire. And calcium waves in the cortex are leading scientists to infer that this style of communication may be conducive to the processing of certain thoughts. If that isn't convincing, it was recently shown that a molecule that stimulates the same receptors as THC can ignite astrocyte calcium release.

LEHRER: You suggest that glia and their calcium waves might play a role in creativity. Could you explain?

KOOB: This idea stems from dreams, sensory deprivation and day dreaming. Without input from our senses through neurons, how is it that we have such vivid thoughts? How is it that when we are deep in thought we seemingly shut off everything in the environment around us? In this theory, neurons are tied to our muscular action and external senses. We know astrocytes monitor neurons for this information. Similarly, they can induce neurons to fire. Therefore, astrocytes modulate neuron behavior. This could mean that calcium waves in astrocytes are our thinking mind. Neuronal activity without astrocyte processing is a simple reflex; anything more complicated might require astrocyte processing. The fact that humans have the most abundant and largest astrocytes of any animal and we are capable of creativity and imagination also lends credence to this speculation.

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choppam at 03:48 PM on 10/29/09
First - "octopi" is a terrible false-learned plural of "octopus". Like the equally terrible false-learned plural "virii" (or a dozen variants) for "virus". The "i" plural is a Latin plural for certain words ending in "us" (not all by a long chalk). "Servus" - slave, plural "servi". "Virus" is a neuter noun in Latin, meaning poison/slime/stink. It doesn't have a plural, and if it did, it wouldn't be "i". Same sort of thing with "octopus". It's from the Greek for "eight-foot" (cf Oedipus - swell-foot). The Oxford English Dictionary (the big one) explains this, and gives the plural as either "octopodes" - the archaic really learned variety, or "octopuses", the normal English-style plural (like "viruses"). "Antipodes" has the same Greek inspired plural - it's an interesting word - look it up!
Second - I love the way this article shows us how we are fighting our way towards an understanding of important things that have been with us for a very long time - like, say, the universe. The object of study remains there for us to examine, regardless of our ideas about it. But the better we get to know it, the better we can relate ourselves to it, and even if we can't control it in any important way, we can use our knowledge to avoid injury and pain, and to increase pleasure and well-being.
Neither the universe nor the brain gives a toss if our attitude is one of worship or contempt. But they can both serve us better if we release them from the mind-forged manacles (mistaken hypotheses or superstitions) we've clapped on them.