Thursday, April 28, 2011

From the DWT Science Desk: Just because you think you're awake doesn't mean all of your brain really is


Well, whose brains did you expect them to test? Right-wingers'? The researchers needed brains that function somewhat like human ones.

"Such tired neurons in an awake brain may be responsible for the attention lapses, poor judgment, mistake-proneness and irritability that we experience when we haven't had enough sleep, yet don’t feel particularly sleepy. Strikingly, in the sleep-deprived brain, subsets of neurons go offline in one cortex area but not in another -- or even in one part of an area and not in another."
-- U. of Wisconsin neuroscientist-psychiatrist Giulio Tononi

by Ken

"Tired neurons caught nodding off in sleep-deprived rats" is the headline on the release issued yesterday by the National Institute of Mental Health (NIMH, one of the National Institutes of Health, or NIH), the source of the above quote from the audaciously adorable Dr. Tononi. The subhead is: "Performance decline belies seeming wakefulness -- NIH-funded study."

(Dr. Tononi and his colleagues report their findings in the April 28 issue of Nature, of which only an asbtract is available free online. Curious how much it would cost to buy the article, I clicked on the link, only to discover that I would have to register for a free account to get any further information. For laughs I tried to register, but got only gibberish for the choices of required information like Affiliation/Employer, Job Title, and Industry. Could their e-form really tell that I'm not really a serious-type person?)

Now I don't suppose the mental defectives of the Right, whose lives are consecrated to never understanding anything, would understand why the NIH would be funding such a study. Hey, who gives a rat's behind about rat's brains, after all? But then, they could hardly have done the study using, say, right-wingers' brains. They need brains that function somewhat like human ones. (I wouldn't be surprised to learn that right-wingers are especially touchy regarding research into compromised brain function.)

For the benefit of people who actually have some interest in understanding human beings and the world around us, and not least our brains, which are our only means of understanding that world around us, here's how the NIMH release encapsules the study findings:
A new study in rats is shedding light on how sleep-deprived lifestyles might impair functioning without people realizing it. The more rats are sleep-deprived, the more some of their neurons take catnaps -- with consequent declines in task performance. Even though the animals are awake and active, brainwave measures reveal that scattered groups of neurons in the thinking part of their brain, or cortex, are briefly falling asleep, scientists funded by the National Institutes of Health have discovered.

This should make it all clear, I think. (You can click on it to enlarge it a bit, if you think that'll help.)

It should hardly come as a surprise that sleep deprivation is a bad thing, a very bad thing. Scientists have been trying to drum that into us for ages now, warning that a lot more than just those of us with diagnosed sleep disorders are suffering varying degrees of sleep deprivation. Sleep deprivation seems to have become a normal state in our go-go-go modern world. What's new here, as far as I can tell, is some appreciation -- at least in the rat brain -- of the brain mechanism whereby parts of it may go sleepytime when the contraption as a whole is officially "awake."

"Previous studies had hinted at such local snoozing with prolonged wakefulness," the NIMH release says. "Yet little was known about how underlying neuronal activity might be changing."
To learn more, the researchers tracked electrical activity at multiple sites in the cortex as they kept rats awake for several hours. They put novel objects into their cages — colorful balls, boxes, tubes and odorous nesting material from other rats. The sleepier the rats got, more subsets of cortex neurons switched off, seemingly randomly, in various localities. These tired neurons' electrical profiles resembled those of neurons throughout the cortex during NREM or slow wave sleep.

And yet, going by their EEGs and their behavior, the little dickenses were awake. This "neuronal tiredness," the report insists, is not to be confused with "more overt microsleep – 3-15-second lapses with eyes closing and sleep-like EEG — that is sometimes experienced with prolonged wakefulness." The researchers consider it "more analogous to local lapses seen in some forms of epilepsy." And "having tired neurons did interfere with task performance":
If neurons switched off in the motor cortex within a split second before a rat tried to reach for a sugar pellet, it decreased its likelihood of success by 37.5 percent. And the overall number of such misses increased significantly with prolonged wakefulness. This suggests that tired neurons, and accompanying increases in slow wave activity, might help to account for the impaired performance of sleep-deprived people who may seem behaviorally and subjectively awake.

The researchers are speculating that "tired neurons might nod off as part of an energy-saving or restorative process for overloaded neuronal connections."

It seems to me that there are potentially large implications for the knowledge that "being awake" doesn't necessarily mean what we've normally taken it to mean, and the hope is that with increased understanding will come some notion of how to deal with it.

Already an alarm has sounded for NIMH Director Thomas R. Insel:
Research suggests that sleep deprivation during adolescence may have adverse emotional and cognitive consequences that could affect brain development. The broader line of studies to which this belongs, are, in part, considering changes in sleep patterns of the developing brain as a potential index to the health of neural connections that can begin to go awry during the critical transition from childhood to the teen years.

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