by Lyudmila ZHAVORONKOVA, Dr. Sc. (Biol.), Leading Researcher, Laboratory of General and Clinical Neurophysiology, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences
Why the number of left-handers is so great among artists, musicians - representatives of the so-called creative professions, while, say, pilots are as a rule right-handers? Why do functions impaired after craniocerebral injuries more rapidly restore in left-handers? What are similarities and differences between people with different individual asymmetry profiles? What are the mechanisms of formation of these peculiarities? The answers to these questions are interesting not only to neurophysiologists, but to specialists of many other spheres of knowledge as well.
Paul Broca, a French anatomist and anthropologist, showed for the first time in 1861 that injury to the left brain hemisphere leads to aphasia (loss of speech), while injury to the right hemisphere is not associated with this abnormality. These data underlie a concept, which existed in science for a long time: the left hemisphere is the leading one in right-handers, while the functional role of the right one is secondary. However, as facts were accumulated, it became clear that the right hemisphere performed many important functions as well. For left-handers the right hemisphere was considered to be predominant for speech, but this opinion proved to be erroneous: the speech representation in individuals with this type of asymmetry can be left-hemispheric and even bilateral (mixed).
According to various data, the number of right-handers in human population varies within 80 - 95 percent, while the rest are left-handers and ambidexters (people with equal potentialities of both hands). Judging by statistical data, the number of left-handers, for example in Europe, increased 3 - 4-fold during the recent half-century, which is justly attributed to overall cessation of their re-training and crea ... Read more