Morphological patterns and spatial probability maps of two defining sulci of the posterior ventrolateral frontal cortex of the human brain: the sulcus diagonalis and the anterior ascending ramus of the lateral fissure

Abstract

The sulcus diagonalis (ds) and the anterior ascending ramus of the lateral fissure (aalf) are two defining sulci of the posterior ventrolateral frontal cortex, which is also known as the anterior language region in the language dominant hemisphere. The aalf extends dorsally from the lateral fissure, separating the pars opercularis from the pars triangularis of the inferior frontal gyrus. The ds, which is a relatively vertical sulcus, is found within the pars opercularis. Given the proximity and similar orientation of these two sulci, it can be difficult to identify them properly. The present study provides a means of differentiating these two sulci accurately using magnetic resonance imaging (MRI). Voxels within the ds and the aalf were labeled in 40 in vivo MRI volumes (1.5 T) that had been linearly registered to the Montreal Neurological Institute stereotaxic space to examine the morphological patterns of these two sulci and classify these patterns based on relations with neighboring sulci. The morphological variability and spatial extent of each sulcus was then quantified in the form of volumetric and surface spatial probability maps. The ds, a rather superficial sulcus, could be identified in 51.25% of hemispheres. The aalf, on the other hand, could be identified in 96.25% of hemispheres and was observed to extend medially, deep below the surface of the hemisphere, to reach the circular sulcus of the insula. Understanding the details of the sulcal morphology of this region, which, in the language dominant left hemisphere, constitutes Broca's area, is crucial to functional and structural neuroimaging studies investigating language.

Morphology and Hemispheric and Gender difference of the Anterior Ascending Ramus and the Horizontal Ascending Ramus of the Lateral Sulcus

“…The aals could be observed in 98.89% of the hemisphere, the hals could be observed in 98.33% of the hemisphere in our study. The results are slightly different from other studies (Sprung-Much and Petrides 2018;Powell et al 2012;Sprung-Much and Petrides 2020;Keller et al 2007). The discrepancy maybe attributed to the great heterogeneity in the brain samples and the differences of sample sizes.…”

Sulcal depth in prefrontal cortex: A novel predictor of working memory performance

“…Sulcal labels in LPFC were based on the most recent parcellation proposed by Petrides (2019; see also Sprung-Much andPetrides, 2018, 2020). In each hemisphere, LPFC sulci in the IFG/ VLPFC and MFG/mid-DLPFC were manually defined at the level of individual participants on both the pial and inflated surfaces (Fig.…”

“Plis de passage” Deserve a Role in Models of the Cortical Folding Process

“…The French anatomist Gratiolet coined first the terms “pli de passage” (Gratiolet 1854; Parent 2014). Later on, the buried gyri were called annectant, bridging or transition convolutions in the English literature, and also submerged gyrus, or submerged gyral passage in recent publications (Germann et al 2005; Zlatkina and Petrides 2010; Huntgeburth and Petrides 2012; Segal and Petrides 2012; Sprung-Much and Petrides 2018). While these plis de passage seem to appear during the earliest stages of development, which shall lead to regard them as candidates for being a distinctive character of the cortex organization, they did not receive a lot of attention.…”

“…But dealing comfortably with unusual folding patterns may require an extended vocabulary (Mangin et al 2016). Several very interesting proposals of extended glossary based on regional folding patterns have been proposed (Steinmetz et al 1990; Germann et al 2005; Zlatkina and Petrides 2010; Huntgeburth and Petrides 2012; Segal and Petrides 2012; Plaze et al 2015; Sprung-Much and Petrides 2018; Snyder et al 2019): each reported pattern often corresponds to a specific configuration of the regional plis de passage, leading to alternative connectivity of the regional sulcal roots. This pattern glossary can be used to perform a subdivision of the population relative to the geometry of the cortical morphology.…”

“…Interesting candidates are the plis de passage interrupting the Superior Temporal Sulcus, which are more developed in the left hemisphere, hinting at a link with the language system (Ochiai et al 2004; Glasel et al 2011; Segal and Petrides 2012; Leroy et al 2015; Le Guen et al 2018b). Another language-related area of interest is Broca’s area, where a submerged gyral passage can often be found separating the sulcus diagonalis from the neighboring sulcus (Sprung-Much and Petrides 2018). A number of plis de passage impacting the geometry of the precentral and the postcentral gyri would also be interesting targets (Germann et al 2005; Amiez et al 2006; Zlatkina and Petrides 2010; Zlatkina et al 2016).…”