Neuronal loss in the human claustrum following ulegyria.

The claustrum is a large subcortical structure that in animals possesses extensive connections with almost all regions of the cerebral cortex. Because there are no data that support the presence of claustrocortical connections in human brain, the main aims of the present study were to confirm the existence of these connections in the human brain. Five control brains and nine brains with bilateral and large ulegyria were studied. Severe neuronal loss in the anterior part of the claustrum was observed after pathological lesions that involved the frontal cortex. Pathological changes localized in the parietal and occipital cortices caused neuronal loss in the central and posterior part of the human claustrum. These findings suggest that the human claustrum is dependent on the neocortex and that, as in animals, it possesses extensive connections with the cerebral cortex that are topographically organized. The anterior part of the claustrum is connected with the frontal cortex, and the central and posterior parts with the parietal and occipital cortices.