[Hemispheric asymmetries of the human brain]

The authors studied 181 brains, 103 of which were dissected. They observed a "T1-T2 bridge" over the first temporal and second temporal gyri more often on the left side than on the right. This asymmetry was more frequent in males than in females. The maximal width of the superior aspect of the second temporal gyrus was greater on the right side in the majority of cases. By contrast, the fusiform gyrus was found wider on the left side in most subjects. The length of the precuneus was greater on the right. The greater size of the left planum temporale could be correlated with the sectional area of the anterior white commissure. The same correlation was found between the length of the precuneus and the area of the latter commissure. Anatomical asymmetries of the two cerebral hemispheres in man seem to be numerous. The interpretation of these asymmetries is difficult; some are likely to be related to functional asymmetries. In the future, the study of morphological asymmetries in routine neuropathology, in patients who have been submitted to detailed neuropsychological examination, would appear to be desirable.