Fly brain wiring alone drives sensorimotor navigation and learning
Sensorimotor behaviour from an untrained brain-and-nerve-cord connectome
Neural and Evolutionary Computing
Summary
Scientists studied how much a fly's behavior can be explained just by its brain and nerve wiring map. They built a detailed model using a fly’s brain connections without training it and found it could navigate towards smells and avoid obstacles. When the model’s sensory input was turned off, this ability disappeared, showing the wiring and sensory feedback both matter. They also showed that changing certain brain connections could reverse the fly’s response to smells, turning attraction into avoidance. This means the fly’s raw brain wiring supports key behaviors and their learning changes.
What this means in practice
- •For robotics engineers: Develop bio-inspired navigation algorithms that rely on fixed neural wiring and sensory feedback to guide robot movement in complex environments.
- •For neural prosthetics developers: Design neuro-controlled limbs or devices that mimic fundamental sensory-motor integrations as encoded by an untrained connectome for improved movement control.
Authors
John R. Minnick, Jesus Gonzalez-Ferrer, Jinghui Geng, Jason K. Eshraghian, Mohammed A. Mostajo-Radji, David Haussler, Mircea Teodorescu
Abstract
Connectomes now map the neurons and synapses of an adult fly's brain and nerve cord, but how much of behaviour follows from the wiring is unknown. Here we turn one such connectome into a spiking network of 172,433 neurons with a published brain model's untuned parameters, and run it alone and inside a simulated body. Two fixed rules join them: odours and looming objects drive sensory neurons, and motor neurons move the legs. Alone, the network passes a signal to the motor neurons it is known to drive when the pathway supplies about 2% or more of their input. In the body, the fly navigates around obstacles to 95% of the odour sources. A rewiring that keeps each neuron's connection counts and signs reaches 18%, and the fly's leg commands replayed with the senses off reach almost none, so navigation needs the measured wiring and sensory feedback. Dopamine-gated weakening of the mushroom body's output synapses turns approach to an odour into avoidance, which requires the pairing and is odour-specific once one olfactory synapse class is scaled. An untrained connectome thus supports a behaviour and its learned reversal, and the pathways it cannot drive mark what the diagram leaves out.