Hemispheric asymmetries in cerebral cortical networks.

Since the middle of the 19th century it has been recognized that several higher cognitive functions, including language, are lateralized in cerebral cortex. Neuropsychological studies on patients with brain lesions and rapid developments in brain imaging techniques have provided us with an increasing body of data on the functional aspects of language lateralization, but little is known about the substrate on which these specializations are realized. Much attention has been focused on the gross size and shape of cortical regions involved, but recent findings indicate that the columnar and connectional structure within auditory and language cortex in the left hemisphere are distinct from those in homotopic regions in the right hemisphere. These findings concern parameters that are closely linked to the processing architecture within the respective regions. Thus, the comparison of these microanatomical specializations with their respective functional counterparts provides important insights into the functional role of cerebral cortical organization and its consequences for processing of cortical information in the implementation of complex cognitive functions.