Cerebral organization in left-handers

We have analyzed the verbal and spatial performances of 141 left-handed and 130 right-handed patients having unilateral hemispheric lesions and that have been grouped according to whether familial sinistrality (FS) is present or not. The present results confirm those of previous studies establishing a relation between FS on one hand and the ambilaterality of the functional representations of language and the lesser intrahemispheric focalization on the other. Such a relation has not only been found with left-handers but, to a lesser extent, with right-handers as well. On the contrary, this type of hemispheric organization does not prevail with respect to spatial functions. These results also allow for the exclusion of any relation between the strength of left-handedness and the pattern of cerebral organization. One finds, nevertheless, some indications that favor the influence of sex on cerebral organization, although it is impossible to specify the interference of this factor.