par Lebrun, Yvan Léopold
Référence Folia Phoniatrica, 35, 1-2, page (13-39)
Publication Publié, 1983
Article révisé par les pairs
Résumé : They are real twins. They were born on the same day, look very much alike, grow in the same way, and, unless one of them becomes severely ill and has to be removed, they will also die on the same day. Yet, when one examines them closely, one finds subtle anatomical differences betwen them. Moreover, their pathology is not the same: Disturbances may be vastly different according to which of them is damaged. For a long time this asymmetry between the two cerebral hemispheres was not recognized. In 1874 Hughlings Jackson observed that 'not long ago few doubted the brain to be double in function as well as physically bilateral'. In the second part of the 19th century it was dicovered that damage to the left half of the brain is likely to entail far more severe language disorders than damage to the right half. The difference was so striking that the left hemisphere came to be regarded as the seat of verbal functions while the right hemisphere was deemed 'uneducated in words'. This, it must be noted, applied only ro right-handers. In left-handers the situation was reversed: The right hemisphere was dominant for language. In the last decades, however, it has become increasingly clear that cerebral organization is more complex and more varied than was imagined at first. Cerebral dominance for language in sinistrals is not always the reverse of what is observed in dextrals. Indeed, there may be various degrees of cerebral dominance for language. Moreover, even in people in whom a pronounced lateralization of verbal functions may be assumed, damage to the minor hemisphere will not leave the use of language completely unimpaired. In conclusion, one might imitate Hamlet and say, 'There are more things in the left and right hemispheres than were dreamt of in early aphasiology'.