June 4, 2007
While most people need peace and quiet to cram for a test, the brain itself may need noise to learn, a recent MIT study suggests. In experiments with monkeys, the researchers found that neural activities in the brain gradually change, even when nothing new is being learned. Challenging the monkeys to adjust their task triggered systematic changes in their neural activities on top of this background "noise."
The researchers said their findings suggest a new theory of how the brain learns.
"What surprised us most was that the neural representation of movement seems to change even when behavior doesn't seem to change at all," said Sebastian Seung, professor of physics and computational neuroscience and a Howard Hughes Medical Institute investigator. "This was a surprising degree of instability in the brain's representation of the world."
Seung and Institute Professor Emilio Bizzi led the study, which was published in the May 24 issue of the journal Neuron. Lead author on the study was Uri Rokni, a postdoctoral fellow in Seung's laboratory.
In earlier work, Bizzi and colleagues measured neural activities in the motor cortex while monkeys manipulated a handle to move a cursor to targets on a screen. In control experiments, the monkeys had to move the cursor to targets in the same way they had been trained. In learning experiments, the monkeys had to adapt their movements to compensate for novel forces applied to the handle.
The scientists found that even when the monkeys were performing the familiar control task, their neural activities gradually changed over the course of the session.
To explore the significance of these background changes, Rokni analyzed the data from the learning component of Bizzi's experiments. He found he could distinguish learning-related neural changes from the background changes that occurred during the control experiments. From this analysis, Rokni developed a working theory that combined the concepts of a redundant neural network and that of a "noisy" brain.
"A good analogy to redundant circuitry, which accomplishes the same behavior by different wiring configurations, would be a piece of text, in which you can say the same thing with different words," Rokni explained. "Our theory holds that the learning brain has the equivalent of a 'teacher' and a 'tinkerer'--a learning signal and noise in the learning process, respectively.
"In producing a specific piece of text, the tinkerer just randomly changes the words, while the teacher continually corrects the text to make it have the right meaning. The teacher only cares about the meaning and not the precise wording. When the teacher and tinkerer work together, the text keeps changing but the meaning remains the same. For example, the tinkerer may change the sentence 'John is married' to 'John is single,' and the teacher may correct it to 'John is not single.'
"In the same way, learning in the brain has two components--error-correction and noise--so that even though the neural representation keeps changing, the behavior remains fixed. We think the tinkerer, that is the noise, is not merely a nuisance to the teacher but is actually helping the teacher explore new possibilities it wouldn't have considered otherwise."
To test this idea, Rokni constructed a mathematical model of a redundant cortical network that controls movement and used it to simulate the learning experiment with the monkeys. In this model, learning of the connections between neurons was assumed to be a considerably noisy process. "When we ran the simulation long enough, the performance became good, but the neural representation kept changing, very similar to the experiments," Rokni said.
According to Rokni, the concepts of redundant networks and "noisy learning" have important implications for neurobiology. "I don't think this concept of redundancy--that the brain can say the same thing in different ways--has really been fully appreciated until now," he said.
"More practically, people who are constructing devices that translate brain signals to operate such external devices as neural prostheses will have to take such constantly changing neural representations into account," said Rokni.
--Courtesy Howard Hughes Medical Institute
Human Brain Still Evolving, Studies Hint
New research suggests that the human brain may still be evolving quite rapidly. Previously, most scientists agreed that human evolution came to a halt 50,000 years ago. But two genes involved in controlling the size of our brains seem to have changed substantially in the last 60,000 years, report University of Chicago geneticists. From the New York Times:
"The new finding, reported in today's issue of Science by Bruce T. Lahn of the University of Chicago, and colleagues, could raise controversy because of the genes' role in determining brain size. New versions of the genes, or alleles as geneticists call them, appear to have spread because they enhanced brain function in some way, the report suggests, and they are more common in some populations than others.
But several experts strongly criticized this aspect of the finding, saying it was far from clear that the new alleles conferred any cognitive advantage or had spread for that reason. Many genes have more than one role in the body, and the new alleles could have been favored for some other reason, these experts said, such as if they increased resistance to disease.
Even if the new alleles should be shown to improve brain function, that would not necessarily mean that the populations where they are common have any brain-related advantage over those where they are rare."
New York Times
Cited by boingboing.net
Surgeons Who Play Video Games Are Better at Laparoscopy
I don't find this surprising at all . . .
From an article in Discover
Your Brain on Video Games
Could they actually be good for you?
By Steven Johnson
Photo illustration by Matt Mahurin
DISCOVER Vol. 26 No. 07 | July 2005 | Mind & Brain
James Gee, a professor of learning sciences at the University of Wisconsin, was profoundly humbled when he first played a video game for preschool-age kids called Pajama Sam: No Need to Hide When It’s Dark Outside. Gee’s son Sam, then 6, had been clamoring to play the game, which features a little boy who dresses up like his favorite action hero, Pajama Man, and sets off on adventures in a virtual world ruled by the dastardly villain Darkness. So Gee brought Pajama Sam home and tried it himself. “I figured I could play it and finish it so I could help Sam,” says Gee. “Instead, I had to go and ask him to help me.”
Gee had so much fun playing Pajama Sam that he subsequently decided to try his hand at an adult video game he picked at random off a store shelf—an H. G. Wells–inspired sci-fi quest called The New Adventures of the Time Machine. “I was just blown away when I brought it home at how hard it was,” he says. “I thought, ‘You can’t tell me that people go to the store and pay fifty dollars and buy this!’ Then I found out that there are billions spent each year on these games.”
and from a Blog, Eat Your Fruits And Vegetables - And Play Video Games:
Laparoscopic surgery, also known as keyhole surgery or band-aid surgery, involves manipulating controls/joysticks to control a fiber optic camera and surgical tools to perform minimally invasive surgery with only tiny incisions in the person’s body. Laparoscopic surgery has been around for many years now, but doctors have only recently begun to notice a stirring correlation between the top surgeons and video gamers.
Surgeon Butch Rosser, directory of minimally invasive surgery at Beth Israel Medical Center in New York, read a reporter’s comments about one of his procedures that referred to him as a “Nintendo surgeon”. This started his thinking that perhaps his apparent gift among many of his peers was because he was a gamer.
Rosser set out to see if there was a correlation by using a standardized laparoscopic training exercise called “Top Gun” to test laparoscopic surgeons that had never played a video game and those that were gamers. “The results were really astounding,” he says. “First of all, if you played video game [at any time] in the past, it was found that you were significantly faster and, more importantly, you created fewer errors than people who had no previous video game experience. Then when we looked at whether you were a current video gamer, we found that if you played video games currently, you were over 30 percent better — faster, and created fewer errors — than someone who did not play video games at all.”
Alan Castel, psychology professor at Washington University of St. Louis, performed another study where people from different groups are given a series of standard visual tests looking for a particular object (e.g. a letter) among a group of other objects on a computer monitor. “Video game players had faster reaction times on the order of 100 milliseconds, which might not sound like a lot but in this domain it’s quite a strong finding,” says Castel. “And you can imagine, when driving, a difference of 100 milliseconds could really help you avoid accidents.”