Anatomical asymmetries of the human cerebral cortex

This paper summarizes current knowledge concerning the anatomical asymmetries of the cerebral cortex and presents the main hypotheses proposed so far to account for these asymmetries. The main question raised by the presence of these asymmetries is that of their functional significance and has been explored by attempting to correlate handedness, the most immediate feature of functional brain specialization, with neuroradiological evidence of brain asymmetry using either carotid angiograms or CT scan. These methods, however, yielded controversial or incomplete results. The recent advent of magnetic resonance imaging now makes it possible to perform direct evaluation and measurements of cortical asymmetries. Preliminary results of a personal study using this approach are presented. They show in particular a good correlation between the planum surface and handedness, and confirm the previously reported statistical correlation between handedness and callosal surface. These results are discussed in the light of modern theories about brain development.