Selection navigates a degenerate circuit space: behavioral individuation without structural differentiation in constrained neuroevolution

Behavioral individuality emerges through functional sensitivity differences in degenerate neural circuits, with 6.4-6.7x higher sensitivity variance despite identical structures across nine mice.

• Why it matters: Understanding how individual behaviors are generated without structural differences addresses fundamental questions about neural circuit flexibility and the role of degeneracy in biological systems.
• What they did: Using constrained neuroevolution, 14-neuron recurrent circuits were evolved across 54 runs to replicate navigation behavior in nine mice, controlling for structural features and topology.
• The result: Behavioral individuation was achieved through differences in functional sensitivity rather than structure, enabling personalized behaviors despite uniform circuit architecture and no shared pathway signatures.