The superior frontal sulcus in the human brain – Morphology and probability maps

The superior frontal sulcus (SFS) is a major sulcus on the dorsolateral
frontal cortex that defines the lateral limit of the superior frontal
gyrus. Caudally, it originates near the superior precentral sulcus (SPRS)
and rostrally, it terminates near the frontal pole. The advent of
structural neuroimaging has revealed that this primary sulcus shows
significant variability below the surface which is not captured by the
classic sulcal maps. The present investigation examined the morphological
variability of the SFS in 50 individual magnetic resonance imaging (MRI)
scans of the human brain that were registered to the Montreal Neurological
Institute (MNI) standard stereotaxic space. Two primary morphological
patterns were identified: i) the SFS was classified as either a continuous
sulcus or ii) the SFS was a complex of sulcal segments. Further, the SFS
showed a high probability of merging with neighboring sulci on the
superior and middle frontal gyri, and these patterns were documented. In
addition, the morphological variability and spatial extent of the SFS were
quantified using volumetric and surface spatial probability maps. The
results from the current investigation provide an anatomical framework for
understanding the sulcal morphology of the SFS, which is critical for the
interpretation of structural and functional neuroimaging data in the
dorsolateral frontal region, as well as for improving the accuracy of
neurosurgical interventions.