Sensory motor boundary changes affect brain network evolution results
Null-model treatment of the sensory-motor boundary changes an evolutionary connectome comparison
Neural and Evolutionary Computing
Summary
Scientists studied how tiny changes in brain wiring affect the evolution of foraging behavior in simulated flies. They found that if random changes in the brain preserve certain connections between sensory inputs and motor outputs, it can greatly influence the outcomes of evolutionary tests. The study shows that how you shuffle or randomize brain wiring in experiments matters a lot, especially at the boundary where sensing meets action. This insight can help improve how researchers compare brain networks fairly.
What this means in practice
- •For neural network engineers: Use insights on preserving sensory-motor connections during randomization to create more biologically accurate brain-inspired networks.
- •For robotics developers: Improve evolutionary algorithms for robot control by carefully controlling sensory-to-motor connection randomizations during simulation.
Authors
Gyujeong Park
Abstract
Randomised copies of a connectome are the usual baseline for asking whether measured wiring matters, and the answer depends on what the randomisation preserves. We evolved embodied foraging agents whose brains are a compressed adult Drosophila connectome (FlyWire v783; 512 cell-type groups and 1,000 Kenyon cells) alongside agents built on randomised wiring, in pre-registered experiments with ten seeds, four ecologies and 600 generations. Two standard randomisations, a column shuffle and degree-preserving edge swaps, route 10.6 to 10.7 % of olfactory output directly onto descending motor groups, against 0.012 % in the connectome. On the registered primary endpoint, fitness averaged over the run, no difference was detected; at the last common-garden probe the connectome was behind both controls (-0.22 and -0.20 fitness units on seed means). Against controls that keep every sensory-output and motor-input edge and rewire only the interior, the seed-mean difference lay within a +/-0.10 equivalence bound (+0.002 and -0.074, unchanged under a calibration that also matches activity spread), although per ecology the interior column shuffle was ahead by 0.26 in one of four ecologies at ten seeds, a lead that ten further pre-registered seeds did not replicate. Rewiring the connectome so that it acquires the shortcut raised its fitness by 0.44 (10 of 10 seeds) and its dependence on olfaction from 0.15 to 0.99; graded doses raised both in step; at comparable swap counts the full dose was ahead of an interior-only sham by 0.53 (10 of 10 seeds); and a sham that rewired the same boundary edges without creating shortcuts matched the connectome (+0.007) while the full dose was ahead of it by 0.60. What a null preserves at the sensory-motor boundary can decide an evolutionary connectome comparison, and sensory-to-motor path statistics belong next to the degree statistics a null is said to preserve.