Anatomia funzionale delle aree cerebrali "dominanti"

Since XIX century, it has been assessed that complex functions are controlled by cortical areas. Sperimental studies have proved a large diffusion of functional lateralization in animals. During the neurogenesis the cell death mechanism (subjected to several inputs as availability of trophic materials or sex hormones) is an important moment for subsequent functional-anatomical organization. About anatomy, it has been observed that cortical areas and anatomic structures functionally connected with language have an asymmetric development or a specific biochemical activity. For example, the planum temporale is larger on the left side; the activity of choline acetyltransferase is more intensive in area 22 of the left hemisphere; the thalamic lateralis posterior nucleus is larger on the left side; norepinephrine, then, is concentrated on the pulvinar. The statement that each hemisphere shows specific skills has been confirmed by neuropsychological, neurophysiological and functional neuroimaging studies. The left hemisphere would seem to be wired for verbal tasks, whereas the right one would be superior in solving perceptive-spatial problems. The speech function uses different circuits with consequent activation-inactivation of numerous cortical areas and subcortical structures, with particular functional competences. The conception of cerebral "dominance" have been replaced by "lateralization" of some functions, partly genetically predetermined, partly subsequent to environmental influences