What makes you you? Is it the cells in your throbbing cerebral cortex, those deep ridges and hills on the surface of your brain, the "little gray cells" that Hercule Poirot speaks of, firing off a drumbeat of awareness?
Look deeper, says Dr. Edgar Garcia-Rill, director of the University of Arkansas for Medical Science's Center for Translational Neuroscience (CTN). Look at the brain stem, which laypeople like this writer might call the lizard brain, the primitive, and essential, part of our brain that keeps our hearts beating, our lungs breathing. There's more going on there, he says: It's where awareness begins. It's why, Garcia-Rill and colleagues say, you know who you are when you wake up, before you start firing on all (usually caffeinated) cylinders. That's because blood flow to the brain stem increases immediately; the cortex doesn't catch up until 15 to 20 minutes later.
The research being done at the CTN, which is funded by the National Institutes of Health, is part of a larger investigation into the mechanics of sleep and wakefulness, and may someday be applied to waking the comatose or anesthetizing the aware. (Hence "translational" - from lab to bedside.) Science has known that the brain stem is involved in waking and sleeping; showing the mechanism on a cellular level "is pretty revolutionary stuff," Garcia-Rill says.
What the CTN team has found is that there is cellular activity in the brain stem that is firing away at the same frequency as that of the wakeful cerebral cortex. Garcia-Rill said he and his team wanted to know "what's this old, sleepy area doing on high frequency?" What it's doing, Garcia-Rill says, is "keeping us aware of the world," or preconscious awareness.
In an example to illustrate how preconscious awareness works, Garcia-Rill asks people to imagine they're in a car, changing from the right to the left lane. If we think about it - off the top of our heads, so to speak - we'll grasp the pretend wheel at 9 and 3 o'clock, turn it to the left and return it to 12 o'clock, just enough to be driving head on into traffic. (Or at least that's what this reporter did.) Our pre-conscious brain knows better, and corrects our movements to keep us from crossing the median. We have to turn back to the right past 12 o'clock to get in the lane, then straighten out.
"Most of the time," Garcia-Rill says, "people are basically asleep at the wheel, but they do survive." He means that literally and virtually. That's because the pre-conscious part of our brain, down in the brain stem, is thrumming with as much energy as the thinking cortex. So while we're thinking about the NPR tear-jerker we're listening to or singing at the top of our lungs we don't run off the road.
Garcia-Rill's team uses cells from the brain stems of rat pups in their research, first described last year. Placed in a bath of cerebrospinal fluid and stimulated by drugs or electrical current, the cells act as if they were still part of a living creature. The team found that the cells generated activity at a frequency of about 40 waves a second - a "significant frequency for learning and memory," Garcia-Rill says, like that of a frisky cortical cell. The UAMS researchers are using various toxins - derived from such surprisingly natural sources as spiders, fish and mamba snakes - to confirm which channels are firing the cells. They found that brain stem cells have the same membrane channels - like pores - as cortical cells.
Work by other researchers using deep-brain stimulation - a treatment for Parkinson's, for example - matches up with Garcia-Rill's theories of preconscious awareness in this primitive area of the brain, showing that electrical brain activity begins before we will our muscles to move. So if you're having a conversation with someone amid a lot of activity, you may ignore what's going on around you until your preconscious brain detects that guy with an axe coming at you (another of Garcia-Rill's examples) and you react. Your lizard brain is taking care of you.
"The cortex doesn't make you you. Higher functions ... don't make you you," Garcia-Rill says. "The essence is down in the brain stem."
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