Brain anticipates events to learn routines

HOUSTON--(Oct. 10, 2002)--A new study at Baylor College of Medicine in Houston helps explain why practice makes perfect. Baylor researchers found that neurons in the visual cortex, the part of the brain responsible for vision, were more active when study monkeys anticipated the occurrence of predictable events. The results of the study were published in the Oct. 10 issue of Nature. "We really don't have a great understanding of what changes in the brain when we practice things," said Dr. Geoffrey M. Ghose, first author of the paper and an assistant professor of neuroscience at Baylor. "These results show that as we practice and anticipate which events are going to happen, the brain is also preparing itself."

Dr. John H. R. Maunsell, a professor of neuroscience at Baylor and a Howard Hughes Medical Institute investigator, is the study's lead author.

Researchers at Baylor trained two macaque monkeys to pay attention to changes at a specific location of a display screen. They were rewarded with juice if they pulled a lever when the change occurred. The activity of neurons in the visual cortex was measured during the experiment.

"Activity in the neurons went up when the event was likely to happen, and went down when it was unlikely to happen," Ghose said. Based on what they see, primates develop expectations of what might happen next. For example, a baseball player anticipates that the pitcher will throw the ball towards him after he winds up, because he has seen him perform this task countless times before. People in every day life also use this function of their brain each time they do something routine, like driving a car or crossing the street.

"Our study gives us some clues of how we make use of our experiences to change specific signals in the brain," Ghose said. "The results are a window into how we represent time. They tell us how accurately we know when things are going to happen and how well we can prepare ourselves."

Physics gets hit for six
Tim Radford, The Guardian, February 24, 2000.
http://www.guardian.co.uk/Archive/Article/0,4273,3966799,00.html

It's just not possible for batsmen to hit a ball, says Tim Radford, science has proved that conclusively...

Certain humans do the impossible almost every day. They are batsmen facing a fast ball. They do not have enough time to calculate how to hit the ball, and they only just have time to hit it. Robert Adair of Yale University has done the physics to prove that what batsmen do ought to be impossible in a time measured in thousandths of a second.

Consider the problem of a man supposed to take a length of timber and swing it in an arc with all his strength to smash into a ball directed towards him from 60 feet away at a speed of 90mph, he told the American Association for the Advancement of Science meeting which ended in Washington DC on Tuesday.

"When we calculate that the time required for a major league fast ball to travel from pitcher to plate to be about 400 milliseconds, we can see that the batter is faced with a totally impossible problem."

Yet major league players did it anyhow. The task was theoretically impossible because the minimum muscular response to a visual signal - the blink of an eye in response to a flash of light - was about 150 thousandths of a second.

Look at it from a batsman's point of view, he told a seminar on the physics of baseball. Information took about 25 milliseconds to be turned into electrical pulses in the retina. These pulses had to get from the sensory cells in the retina to the bundle of nerve fibres that processed information at the back of the brain. Signals might travel at nearly the speed of light down a copper wire, but they slowed down to 200 mph along the nervous system. So the information took about 20 milliseconds to reach the back of the brain, and about another 30 milliseconds before it could be turned into a picture.

But even 75 milliseconds after the ball left the pitcher's hand, the eye needed more data before the brain could calculate the ball's trajectory.

At 100 milliseconds, the ball would already have traveled 14 feet, and be one quarter of the way towards the plate. At that point, the batter did not have nearly enough information about the ball's speed. On the other hand, if he left the decision any later, he would not have time to make his swing.

"With 75 milliseconds required to process that last informative picture added to the 100 milliseconds, the brain-computer picture gets to 'think' about the pitch only after 175 milliseconds have elapsed and the fast ball is three eighths of the way through its trip to the plate," Dr Adair said.

By the time the batter had made the decision, and his brain had begun to send messages to arm and leg muscles, 225 milliseconds had elapsed and a swing which takes 150 milliseconds had begun. It took around 15 milliseconds for a signal to get from brain to thigh and 10 milliseconds to distribute the signal through the muscle fibres.

So the swing had to begin a quarter of a second (250 milliseconds) after the ball left the pitcher's hand if the bat was to meet the ball at 400 milliseconds. If the swing by a right handed batter was seven-thousandths of a second too early or late, he would connect but the ball would travel foul. In the first 50 milliseconds of the swing, the batter might be able to adjust the direction.

"At the end of that time, the bat is traveling at about three fourths of its final velocity," said Dr Adair. "Even if the skilled batter can use this late data, none of the subsequent information from seeing the ball over the last half of its flight can be used at all.

"If it weren't psychologically upsetting, the batter could as well close his eyes after the ball is halfway to the plate, or if it were a night game, the management could turn out the lights. The batter would hit the ball just as well."