Neuroscience Subnetwork Seminar

June 26 at 10:00 AM in Brazil (UTC-3)

Bruno Mota

Universidade Federal do Rio de Janeiro (UFRJ), Brazil

Title:  A new morphological syntax for the cerebral cortex

Abstract:  Beneath the striking diversity of mammalian cerebral cortex shapes lies a deep regularity: a theory‑derived morphometric scaling law for brain folding (“gyrification”) holds with precision across terrestrial mammals. The law describes a self‑similar folding pattern with a fractal dimension of 2.5 and a conserved fundamental aspect ratio for sulci and gyri. Coarse‑graining (or “melting,” in a visual analogy) the smallest folds of an adult human cortex yields shapes resembling chimpanzee cortices, then small monkeys, then smooth‑brained lemurs; in this sense, mammalian cortices approximate an archetypal fractal shape, differing mainly in the range of length scales over which the approximation holds. Cetaceans (dolphins and whales), however, deviate from this pattern: their melting trajectories in morphometric space differ sharply from those of terrestrial mammals, exhibiting distinct fractal dimensions while retaining the same fundamental aspect ratio. The origin of this divergence remains unresolved and may reflect the mechanical response of brain tissue to elevated hydrostatic pressures. Cortices are, moreover, dynamical objects whose morphology changes continuously from gestation through old age. Although the cortices of small monkeys and second‑trimester human fetuses are both small and ungyrified, we show that their melting trajectories are fundamentally different: ontogeny does not recapitulate phylogeny, and development and evolution follow distinct paths, revealing that cortical form emerges from distinct underlying processes across different timescales.

Extended Abstract

Zoom meeting number:  871 1205 0573

Zoom password: polsan