19 August 2009

Neuroplasticity and handedness

I used to be ambidextrous.

When I was a child I had the ability to use either hand for most tasks. It was useful but also confusing. I had a nagging feeling that I should be settling on exactly which hand I should use to draw my pictures with. There wasn't much pressure from the adults around me to settle this internal argument but any suggestions I did receive from outside always favoured the right.

I now wonder if I lost something when I finally settled on using my right hand. Some of the old 'confusion' is still there - when cutting with scissors I use my left hand; when playing pool or darts my left hand dominates.

Having now read a fair amount about neuroplasticity - Norman Doidge's "The Brain That Changes Itself" is a particular favourite - I think that my ambidextrous abilities were a result of an earlier and more readily plastic phase of my brain's development. Once settled into a less readily plastic phase the right hand came to dominate. But can that process cause an imbalance?

I would assume that an imbalance would be more likely in an obviously left-handed child forced to use their right. This still happens - the old sinister/dexter nonsense. But when this happens more internally can it be a case of the left brain (right hand) achieving dominance over the right brain (left hand)? The probable answer is that it is much more complicated than that. Left-handed people do not necessarily have a more dominant right brain than right-handed. But I wonder if some of the 'flexibility' of thought and motion from the more plastic and ambidextrous phase would be better retained than lost.

I have started brushing my teeth and sometimes shaving with my left hand. This feels awkward and unnatural at first but it does appear to get easier after a few weeks. A kind of 're-learning' may be happening.

This would seem to tie in somewhat with current neuroplasticity research. There is growing evidence, for example, that stroke victims who lose the use of a limb, can learn to use that limb again by restricting the movement of the good limb. In the case of an arm the good limb could be put in a tight sling so that the non/semi-functional limb is 'forced' into use. Is it so different to try to force a once highly functional hand to undertake some of the tasks now so ably performed by its opposite number in an effort to regain some of its 'lost' function?

Someone I know has, in the fairly recent past, lost a good deal of the function in one leg. He insists the problem is entirely 'physical' and localised to the area of the leg itself, while at the same time talking about how the limb 'won't obey his commands'. It is clear to me that the damage has resulted from a small stroke but the affected person will never agree with this because of the stigma he sees attached to such a brain-associated dysfunction. The physiotherapists he has seen have made no real effort to investigate the root of the problem. I have suggested some kind of restrictive therapy to 'force' the affected limb into better use but he won't hear of it. Meanwhile the leg becomes less functional with each passing day.

Brain plasticity is never lost but it does become harder to 'activate' as the years go by. Exercises, both physical and mental, which re-activate and promote neuroplasticity can be of huge benefit to all. There appears to be resistance in some quarters to the notion of training the brain like a muscle or using it as 'tool' to effect change in itself and in the rest of the body. Some of the methods touted for achieving plastic change are pure hokum but others, such as the software developed by Posit Science, may just have a chance of making a real difference for those struggling with weakening mental agility.

I won't ever be fully ambidextrous again but that doesn't mean I should give up on my left hand. Balance in all things.

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