From skull to brain: 3D density maps of cortical sulci as a powerful tool for paleoneurology

International audienceThe timing and emergence of derived cerebral features in the human linage remains a key question in palaeoneurology.ln order te reconstruct a timeline of hominin brain evolution using the fossil record, palaeoneurologists have to rely on endocasts which are replicas of the inner table of the bony braincase. The accurate identification of cerebral sulci imprints in endocasts is critical for assessing the topographie extension and structural organisation of cortical regions. This study aims ta provide the first documentation of sulcal pattern imprints from the superolateral surface of the cerebrum using a population based atlas technique on extant human endocasts. Human crania from the Pretoria Bane Collection (South Africa) were scanned using micro-CT. Endocasts were virtually extracted,and suIci were automatically detected and manually labelled.A density map method was applied to project all the labels onto an averaged endocast and to visualise the mean distribution of each identified sulcal imprint. This method allowed for the visualisation of inter-individual variation of sulcal imprints,e.g.,frontal lobe sulci,correlating with previous brain-MRI studies, and for the first time the extensive overlapping of imprints in historically debated areas on the endocast (e.g., occipital lobe). ln providing an innovative, non-invasive,observer-independent method to investigate human endocranial structural organisation,our analytical protocol introduces a promising perspective for discussing critical hypotheses on the evolution of cognitive abilities among hominins