The complex history of the fronto-occipital fasciculus.

We investigated the history of the fronto-occipital fasciculus (FOF) and related tracts in the cerebral white matter because of their contemporary relevance for connectional neuroanatomy, magnetic resonance tractography, and clinical neurology. The term "FOF" originated with Forel and Onufrowicz who misidentified aberrant longitudinally oriented callosal fibers in patients with callosal agenesis. This error was soon recognized, and Dejerine described an actual FOF linking frontal and occipital lobes, but gross dissection and lesion-degeneration methods could not distinguish the FOF from the subcallosal fasciculus of Muratoff and neighboring white matter bundles. Subsequent descriptions of a probably nonexistent "inferior FOF" have led to the FOF being misnamed post-hoc "superior FOF," and other imprecise anatomical concepts and terminologies from the early literature are still perpetuated. Our analysis of brain fiber pathways using isotope anterograde tract tracers (Schmahmann & Pandya, 2006) resolves the earlier uncertainties and provides hypotheses regarding functions of these fiber pathways.