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What makes you a lefty or a righty?

London, Feb 19: It is not the brain that determines whether a person is a lefty or a righty, but the spil cord, a study has claimed. Until now, it had been assumed that differences in gene activity of the right and left hemisphere might be responsible for a person’s handedness — people’s tendency to turally favour the use of one hand over the other.

But the recent study demonstrated that gene activity in the spil cord is asymmetrical already in the womb and could be linked to the handedness of a person.

“Our findings suggest that molecular mechanisms for epigenetic regulation within the spil cord constitute the starting point for handedness, implying a fundamental shift in our understanding of the ontogenesis of hemispheric asymmetries in humans,” said Sebastian Ocklenburg from Ruhr University Bochum in Germany.

According to ultrasound scans carried out in the 1980s, a preference for moving the left or right hand develops in the womb from the eighth week of pregncy. From the 13th week of pregncy, unborn children prefer to suck either their right or their left thumb.

Arm and hand movements are initiated via the motor cortex in the brain. It sends a corresponding sigl to the spil cord, which in turn translates the command into a motion.

However, the motor cortex is not connected to the spil cord from the beginning. In fact, even before the earliest indications of hand preference appear, the spil cord has not yet formed a connection with the brain, stated researchers in the paper.

In addition, environmental factors were found to be controlling whether spil cord activity was greater on the left or right side.

For the study, the team alysed the gene expression in the spil cord during the eighth to 12th week of pregncy and detected marked right-left differences in the eighth week — in precisely those spil cord segments that control the movements of arms and legs. (IANS)

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Ankur Kalita