Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Date Vendredi 17 Juin 2022
Heure 13:00
Institut LPENS
Salle Salle Favard, IBENS
Nom de l'orateur Fiete
Prenom de l'orateur Ila
Addresse email de l'orateur
Institution de l'orateur Massachusetts Institute of Technology
Titre From smooth gradients to discrete modules: a topologically robust model of structure emergence
Résumé Modular structures in the brain are hypothesized to play a central role in intelligence by permitting compositional representations, but the general mechanisms driving discrete structure emergence from more-continuous genetically specified morphogens have remained elusive. Grid cells represent self-location during navigation in 2D spaces with spatially periodic codes of a small number of discrete periodicities. They present a paradigmatic example of the computational advantages of modular representations– permitting exponential representational capacity and strong intrinsic error-correction by representing a continuous euclidean variable (location), with a modular set of position-encoding phases. Underlying this discrete modular coding, which emerges rapidly postnatally, are biophysical gradients that vary smoothly. I will consider how smooth gradients can give rise to globally discrete function through self-organization in the context of this system. We show that two purely local lateral interactions, one with a smoothly graded parameter in the brain and another without a spatial gradient can simultaneously give rise to local pattern formation and global modularity. We show that this mechanism of modularity emergence is highly generic, robust, and almost completely insensitive to parameters because it is a topological process. The model makes predictions for the relationships between modules that furnish the most accurate match to data to date. Abstractly, the mechanism involves dynamics on the sum of two energy landscapes, one of which is a shallow global minimum that smoothly moves with the spatial parametric variation, and the other of which is a static landscape with multiple narrow minima. We believe this is a novel self- organization mechanism by which simple local interactions and smooth gradients may interact to induce macroscopic modular organization.
Numéro de preprint arXiv
Commentaires Participer à la réunion Zoom ID de réunion : 950 2468 9955 Code secret : MuTzn4
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