Frontal Aslant Tract (FAT) and its role in language: A journey through tractographies and dissections

Abstract

Introduction The Frontal Aslant Tract (FAT) is a bilateral tract located within each frontal lobe. It connects the supplementary motor area in the superior frontal gyrus (SFG) with the pars opercularis in the inferior frontal gyrus. There is a new and broader conceptualization of this tract called the extended FAT (eFAT). The eFAT tract role is thought to be related to several brain functions, including verbal fluency as one of its main domains.

Materials and methods Tractographies were performed by using DSI Studio software on a template of 1065 healthy human brains. The tract was observed in a three-dimensional plane. A Laterality Index was calculated based on the length, volume, and diameter of fibers. A t-test was performed to verify the statistical significance of global asymmetry. The results were compared with cadaveric dissections performed according to the Klingler technique. An illustrative case enlightens the neurosurgical application of this anatomical knowledge.

Results The eFAT communicates the SFG with Broca's area (within the left hemisphere) or its contralateral homotopic area within the non-dominant hemisphere. We measured the commisural fibers, traced cingular, striatal and insular connections and demonstrated the existence of new frontal projections as part of its main structure. The tract did not show a significant asymmetry between the hemispheres.

Conclusions The tract has been successfully reconstructed, focusing on its morphology and anatomical characteristics.