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About one-third of the population have 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, Dr Tilmann Klein, said in an interview.
About 30 per cent of the population have the mutation, called the A1 mutation, said co-author Dr 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.
Some just repeat mistakes
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, published in the journal Nature, they found that men with fewer D2 receptors had trouble avoiding their mistakes.
30 percent of population affected
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 A1 must offer some genetic advantages," Klein told Focus news magazine.
"Some individuals persist even in the face of negative feedback, and doggedly persevere as long as it takes until they finally succeed," he said. – (Sapa)
December 2007
