IANS

Washington, Jul 30: If you've ever felt doomed to repeat your mistakes, researchers can explain why. Brain cells seem to learn only when we do something right and not when we fail.

Earl K. Miller, professor of Neuroscience at the Massachusetts Institute of Technology (MIT), and colleagues have created for the first time a unique snapshot of the learning process that shows how single cells change their responses in real time as a result of information about what is the right action and what is the wrong one.

"We have shown that brain cells keep track of whether recent behaviours were successful or not," Miller said. Furthermore, when a behaviour was successful, cells became more finely tuned to what the animal was learning.

After a failure, there was little or no change in the brain -- nor was there any improvement in behaviour.

The study sheds light on the neural mechanisms linking environmental feedback to neural plasticity -- the brain's ability to change in response to experience. It has implications for understanding how we learn, and understanding and treating learning disorders.

Monkeys were given the task of looking at two alternating images on a computer screen. For one picture, the animal was rewarded when it shifted its gaze to the right; for another picture it was supposed to look left. The monkeys used trial and error to figure out which images cued which movements.

The researchers found that whether the animals' answers were right or wrong, signals within certain parts of their brains "resonated" with the repercussions of their answers for several seconds.

The neural activity following a correct answer and a reward helped the monkeys do better on the trial that popped up a few seconds later.

"If the monkey just got a correct answer, a signal lingered in its brain that said, 'You did the right thing.' Right after a correct answer, neurons processed information more sharply and effectively, and the monkey was more likely to get the next answer correct as well," Miller said.

"But after an error there was no improvement. In other words, only after successes, not failure, did brain processing and the monkeys' behaviour improve."

These findings were published in the Thursday issue of Neuron.