Year: 2026
Type: preprint
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.
Source: PubMed
Institution: University of California, Santa Cruz
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Awards: G1585335955, CI-New: Cognitive Hardware and Software Ecosystem Community Infrastructure (CHASE-CI), NSF2026: EAGER: The evolution and diversity of the human brain, EFRI BEGIN OI: Reinforcement Learning for Scalable Biocomputing, Advancing Therapeutic Discovery Through Multimodal Analyses of Genetic and Cellular Mechanisms in Neuropsychiatric Disorders, Deep phenotyping of human brain organoid models of autism spectrum disorder to unravel disease heterogeneity and develop biomarkers and treatments, Defining Neurovascular Metabolism in Neurodevelopmental and Neuropsychiatric Disorders, Towards Deploying a Science-Driven Regional Interoperable Science DMZ, G4923312906, CC* NPEO: Toward the National Research Platform, G5218904322, RECODE-ing the Logic of Ectodermal Organoid Patterning via Combinatorial Morphogen Treatments and Longitudinal Monitoring, CCRI: ABR: Cognitive Hardware and Software Ecosystem Community Infrastructure (CHASE-CI), Category II: A Prototype National Research Platform, G6423641252, G6632354235, Unraveling disease pathways for autism spectrum disorder with phenotyping of human brain organoids., CC*DNI DIBBs: The Pacific Research Platform, CCRI: ENS: Cognitive Hardware and Software Ecosystem Community Infrastructure (CHASE-CI), Data Resource and Administrative Coordination Center for the Scalable and Systematic Neurobiology of Psychiatric and Neurodevelopmental Disorder Risk Genes Consortium
OpenAlex ID: W7223941030