The term superior precentral dimple (spd) refers to a superficial feature of the frontal lobe (FLB) in the macaque. It is a short horizontal depression located in the superior frontal gyrus (SFG) just anterior to the central sulcus (cns) ( Bonin-1947 ). Though sometimes referred to as the superior precentral sulcus (sprs) ( Szabo-1984 ), it is probably not homologous to the sprs of the human. [See arcuate sulcus (arc) of the macaque.] An equivalent feature is not seen in the smooth cerebral cortex of the rat or mouse ( NeuroNames ). Final 26 Mar 2025.