Muellen, A. M. | bioRxiv Science

bioRxiv2025

Characterization of the central sulcus pli-de-passage fronto-parietal moyen in > 1000 human brains

The pli-de-passage fronto-parietal moyen (PPfpm), a deep cerebral fold of the human brain, presents as a common though small elevation at the central sulcus (CS) fundus where it connects the pre- and postcentral gyri at the level of the sensorimotor hand area. Given the PPfpms location, single case-reports of its association with the functional sensorimotor hand area, and evidence linking it to the somato-cognitive action network, it holds potential as an anatomical landmark for the sensorimotor region. To characterize the macroscopic morphology of the PPfpm and evaluate its relevance as a reliable and easily detectable anatomical landmark, methods for observer-independent characterization of cortical sulci and structures were adapted and developed to investigate the PPfpm in a large dataset. For 1112 subjects from the Human Connectome Project Young Adult S1200 Release, CS depth profiles were computed from structural magnetic resonance imaging (MRI) data, and an algorithm was developed to automatically extract the PPfpm from these depth profiles. Based on the extraction of two key features approximating the PPfpm at its peak height (PPfpm-I) and its lateral end (PPfpm-II), a principal description of the PPfpms position and extent as influenced by hemisphere and sex was conducted. Analyses revealed the PPfpm as a near-universal cerebral fold in the adult human brain, consistently located at mid-height within the CS with a strong association to the CS sulcal pits. Though commonly of a small extent, the PPfpm can be reliably identified in CS depth profiles and in structural MRI data. By providing a systematic, modern macroanatomical characterization of the PPfpm in a large cohort with rigorous quality control, the present study demonstrates the potential of the PPfpm to serve as a robust anatomical landmark for the sensorimotor hand area of the human brain.

neuroscience↗

bioRxiv2024

The deep winding at the brain surface: replicating a historical report associating the 'bridged' central sulcus with the pli de passage fronto-parietal moyen

In 1876, the anatomist Heschl surveyed 1,087 brains identifying six cases of a unilateral bridged central sulcus (CS) at the brain surface. He also measured the height of a minor deep winding at the same location within the CS in the remaining 1,081 brains, reporting a distribution skewed towards significantly increased heights. These observations supported his hypothesis that the bridged CS represents an extreme form of the deep winding within the CS. In this replication we examined structural MRI data from an equally large dataset of 1,112 participants of the Human Connectome Project young adult (HCP-YA) dataset. Through visual inspection, we identified nine cases of a bridged CS, confirming its prevalence of less than 1%. The height of the deep winding, referred to in the HCP-YA dataset as the pli de passage fronto-parietal moyen (PPfpm), was extracted from 1,983 MRI-based hemispheric depth profiles. The resulting PPfpm height distribution, although wider, still mirrored Heschls findings, showing a similar skew towards larger heights. Further analyses of the twin data within the HCP-YA dataset indicated a slightly increased prevalence of the bridged CS in monozygotic and dizygotic twins compared to non-twin individuals, though no concordance of bridged CS was observed in monozygotic twin pairs. This replication study validates both of Heschls observations, describes additional factors that might influence the prevalence of the bridged CS, and refines the characterization of the deep winding height distribution. Together, these findings reaffirm and expand historical insights into the intricate anatomical organization of the CS.

neuroscience↗