Converting Left-hander to Right-hander also Changes the Brain

A study of “converted” left-handers, natural lefties who have switched over to right hand use, has shown that such a shift changes the way their brains are organized, and how hard particular regions work.

The researchers say while some areas in such people’s brains continue to retain characteristics of a practising lefty, other areas switch to the patterns of a righty.

"The question now is, 'do converts suffer because of this extra attention that they exert?'" Nature magazine quoted Stefan Kloppel of University College London, who led the study, as saying.

While writing, the left hand of a person is generally controlled by the right side of the brain, and vice-versa. However, in the current study, the researchers found that converting from left-hander to right-hander did not simply move brain activity to the other half of the brain.

In the course of study, right-handers, left-handers and “converted left-handers” were given a simple task to perform, in which they had to press a button with one of the other hand in response to seeing particular symbols. Throughout the task their brain activity was monitored with a magnetic resonance imaging (MRI) scan.

The researchers found that one movement-related area of the brain was most active in the right hemisphere for left-handers, and in the left hemisphere for right-handers, including converted left-handers. But the activity in this region was greater in the converts.

However, a second set of brain regions involved in planning movement continued to act like those of left-handers in people who had switched to right-handedness. These regions were also more active in converts than in those who stuck with left-handedness.

"They still look like left handers, but even more emphasised," says Kloppel.

Clare Porac, a psychologist at Pennsylvania State University, feels that there might be greater activity in the brains of converted lefties, but still it would be too early to conclude that they are adversely affected.

"I wouldn't interpret that their brains are working harder," she says.

She notes that most converted lefties are ambidextrous, and this fits in well with the fact that there was activity on both sides of their brains.

Working in collaboration with Brazil-based researcher Lee Martin of the Federal University of Para in Belem, Porac has also found that in people who change their writing hand, other behaviours remain firmly left-handed.

Klöppel is of the opinion that he new study may reveal things about the brain beyond its involvement in handedness, as it shows how flexible the brain is in terms of which regions can do what.

"The key thing is that there are areas that can be influenced by training and areas that resist this. It's not only interesting in regard to handedness, but also in terms of plasticity," he says.

Source-ANI
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