Characterization of the Central Sulcus Pli-De-Passage Fronto-Pariétal Moyen in > 1000 Human Brains

The pli-de-passage fronto-pariétal 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 PPfpm's 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 PPfpm's position and extent as influenced by hemisphere, handedness, 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 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 and digit area of the human brain.