The Human Frontocorticopontine Tract

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Abstract
The author has severed the fibers in the anterior limb of the internal capsule in 22 humans and the medial half of the mesencephalic peduncle in another case. Death ensued in 3 instances and autopsy confirmed the intended lesions. Among the survivors, in whom detailed pre- and postoperative neurologic assays were performed, 15 appeared especially pertinent. No deficits in motor power, synergy, eupraxia, muscle tonus, deep and superficial reflexes, equilibratory coordination, cutaneous and proprioceptive sensory functions were discernable, although the operative lesion presumably severed the frontocorticopontine tract in each instance. These findings cast doubt on the "functions" heretofore assigned to the tract in the human and suggest that the tract is but one of several available pathways in the plenum of complex parallel loops by means of which human neural "functions" are executed. Only when the corticofugal impulses are blocked in sufficient numbers do clinically demonstrable derangements appear.