The organization of corticopontine fibres in man.

Patients with lesions located in the frontal and temporal lobes, in the parieto-temporo-occipital border zone, and in the anterior limb of the internal capsule, did not present ataxia or other cerebellar signs. On the other hand, patients with the ataxic hemiparesis (AH) syndrome had lesions located in the posterior limb of the internal capsule, in the corona radiata and in the central region of the cerebral cortex. These findings in man do not confirm the existence of large frontal (Arnold's bundle) and temporal (Türck's bundle) projections to the pontine nuclei and indicate that the main bulk of corticopontine fibres originates from the central region of the cerebral hemisphere and courses in the posterior limb of the internal capsule. In man, the anatomical organization of corticopontine fibres is therefore similar to that recently demonstrated in animals.