Saturday, January 5, 2008

Stubbornness runs through the veins of some: Study

People who are stubborn and never seem to learn from their mistakes may have a mutated gene that makes them bull-headed, according to scientists in Germany.

About one-third of the population has this mutation, which may be nature’s way of ensuring that there are always some people who will not give up trying when at first they do not succeed, say the researchers at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany.

"Where would we be without those few individuals who refuse to accept defeat and who continue to soldier onwards when common sense tells the rest of mankind that there’s no use trying?" one of the authors of the study, Tilmann Klein, said in an interview.

About 30 per cent of the population has the mutation, called the A1 mutation, said co-author Markus Ullsperger.

The A1 mutation, the researchers say, leaves people with fewer D2 receptors in the brain that are activated when levels of the neurotransmitter dopamine drop. Dopamine is not only responsible for signalling fun and pleasure in the brain, but the neurotransmitter also helps in learning.

Klein and Ullsperger theorise that the lower output of dopamine means that some people simply are not satisfied when a decision or action turns out to be a mistake. So they repeat their mistakes. People with more D2 receptors in their brains are satisfied the first time around that a mistake is a mistake. They do not feel any desire to repeat it.

The researchers studied a group of 26 men, 12 of whom had the A1 gene mutation for low numbers of D2 receptors. As a part of the study the subjects were shown sets of two symbols on a computer screen, and were asked to select one. The choice was followed by either a smiling face or a frown flashing on the screen. The researchers then tested to check whether the men had learnt to choose the symbol that was the most positively reinforced and avoid the one that was the most negatively reinforced.

According to results of the study, they found that men with fewer D2 receptors had trouble avoiding their mistakes. Brain imaging then was used to confirm that the region called the rostral cingulate zone was involved in learning from mistakes. This particular region was found to be more active in the volunteers with normal D2 levels during the learning sessions, compared to those with the D2 mutation. A brain region key to forming memories, the hippocampus, was also more active in the volunteers with normal D2 levels.

"The fact that nearly 30 per cent of the population has this A1 mutation, we can only surmise that it must offer some genetic advantages," Klein said. "Some individuals persist even in the face of negative feedback, and doggedly persevere as long as it takes until they finally succeed," he said.