Working in Movement

The brain makes sense of things, including senses. That is, the brain does things with information from the senses that reach the brain. See dark clouds in the sky, and you brain arranges the visual information, combines it with things already stored there, and gives you the idea that taking your umbrella might not be a bad idea. The brain has made a prediction by combining what's coming from you eyes with some of the stuff that's already there. Our brains like to recognize familiar patterns and reliably predict what's going on now and in the foreseeable future.

But sometimes things get jumbled up. You might see or hear something unfamiliar that needs sorting out, brain-wise. Or maybe the brain itself gets a little confused, but it still faithfully tries to sort out what's happening and what will happen. Even if it doesn't make sense, the brain seems to try to make sense out of almost any situation. And it turns out it's not just the information coming into the brain that counts in the accuracy and usefulness of the sense begin made.

At least that's one of the ideas I got from reading about a recent bit of research at the Washington University School of Medicine in St. Louis. There researchers found that they could tell whether or not people would be successful at a simple guessing game, at least most of the time.

The game involved guessing which way some arrows would point on a video screen. Just prior to the arrows appearing, a hint would appear on the screen for a fifth of a second. Those who paid attention to the hint could easily guess which way the arrows would be pointing. Except that, like a rigged roulette wheel, the hints were accurate only 80% of the time, and that was determined by a computer-generated random number.

How did the researchers know the likelihood of success? The test was done in brain imaging device that showed a spike in activity in the area of the frontal brain lobes usually concerned with rewards, as well as other areas involved in prediction. The participants wanted their reward of guessing correctly, so their brains acted accordingly.

"The rewards system is involved in regulating behavior based on previous experiences of rewards and punishments," coauthor Giovanni d'Avossa, M.D., an instructor in neurology, says. "It also may help us build up predictions of what the world should be like and how certain events go together. When it works well, the world makes sense to you."

But the game was rigged, almost predictable but not absolutely reliably so. But the participants' brains still tried mightily to perform accurately, according to d'Avossa.

"But regardless of how hopeless it was to try to outguess the computer, some of our data suggest that the brain may still have been trying to do just that: to figure out a formula or a rule based upon which it could predict whether a hint was valid and should be trusted."

Most of us can sort out situations despite receiving questionable information from one of our senses. But one of the researchers theorizes that damage to the brain areas observed would be particularly troublesome, making the world an unpredictable and alien place to hang out. Nonsense coming in would not get sorted out, but still the brain would attempt some interpretation.

Trying to make sense of what's going on in the world isn't just a matter of the quality or reliability of sensory information reaching the brain. It has a lot to do with the information that's already there, and the integrity of the structures holding them.

"These activations may reflect the degree to which subjects variably directed attention on each trial to the location of the stimulus prior to its presentation," says Maurizio Corbetta, M.D., the Norman J. Stupp Professor of Neurology and senior author of the study. Regardless of how the results are interpreted, Corbetta notes, the study clearly showed that visual perception not only depends on the quality of sensory signals but also on the variability of internal signals.