Off the map. Neurosciences keep redefining the brain’s functional areas. Models of cortical development continue to evolve, blending gene- and experience-driven mechanisms, but one notion seemed widely accepted: the vertical positioning of neurons in the cortex appeared essential. The results of this study challenge that idea. Heterotopic neurons that migrated beneath the cortex display the same molecular identities and connections as normal cortical neurons, and may even take over their function! Despite the epilepsy that ultimately results from this double cortex, the findings suggest that neuronal position may be less decisive than previously thought.

Scientific abstract: Brain architectures vary widely across species, yet how neuronal positioning constrains the type of circuits that can be made, and their function, remains poorly understood. Here we examine how neuronal position
affects molecular identity, connectivity and function by studying Eml1 knockout mice, which exhibit abnormally located (heterotopic) neurons beneath the cortex. Heterotopic neurons maintained their molecular signatures, formed appropriate long-range connections and exhibited coherent electrophysiological properties. They organized into functional sensory-processing centers that mirrored their cortical counterparts, with preserved somatotopic mapping and responsiveness to sensory stimuli. Remarkably, cortical silencing did not impair sensory discrimination, revealing that heterotopic neurons were the main drivers of this function. Hence, equivalent circuits can emerge in different spatial configurations, allowing diverse brain architectures to converge on similar functional outcomes.

The authors: S Roig-Puiggros, M Guyoton, D Suchkov, A Fortoul , G Matteucci, S Fièvre, A Panzeri, N Molochidis, F Barcellini , E Maino, C Foucher, D Fuciec, A Javed, E Klingler, F Francis, V Zerbi, C Bellone, M Minlebaev, S El-Boustani, F Watrin, JB Manent & D Jabaudon

Paru dans Nature Neuroscience, 2026