P232 Centralized brain networks underlie grooming body part coordination
Pembe Gizem Ozdil*1,2,Clara Scherrer1, Jonathan Arreguit2, Auke Ijspeert2, Pavan Ramdya1
1Neuroengineering Laboratory, Brain Mind Institute & Interfaculty Institute of Bioengineering, EPFL, Lausanne, Switzerland 2Biorobotics Laboratory, Institute of Bioengineering, EPFL, Lausanne, Switzerland
*Email: pembe.ozdil@epfl.ch Introduction
Animals must coordinate multiple body parts to perform essential tasks such as locomotion and grooming. While locomotor coordination has been extensively studied [1,2], less is known about how the nervous system synchronizes movements across distant body parts, such as the head and legs, to execute complex behaviors. Antennal grooming inDrosophila melanogasterprovides a powerful model to study such coordination, as flies exhibit a rich repertoire of precisely controlled limb movements. With a compact yet fully mapped nervous system,Drosophilaenables circuit-level insights into how neural networks integrate motor commands for efficient multi-limb control.
Methods
Here, we combined behavioral analyses, biomechanical modeling, and connectome-based neural circuit simulations to investigate how flies coordinate head, antennae, and forelegs during grooming. We tracked detailed movement kinematics in freely behaving flies using 3D pose estimation[3]. To understand the functional role of coordination, recorded movements were replayed in a biomechanical simulation (NeuroMechFly [4]) to measure contact forces. To test proprioceptive contributions, we performed limb amputations and head immobilizations. Lastly, we analyzed the antennal grooming network using graph-based and computational neural network simulations derived from the brain connectome [5].
Results
Flies exhibit two main grooming strategies, unilateral and bilateral antennal grooming, each requiring precise coordination of head, antennae, and forelegs. Biomechanical simulations revealed that this coordination enhances grooming efficiency by avoiding obstructions and enabling forceful limb-antennal interactions. Manipulations showed proprioceptive feedback is not necessary for body-part synchronization, implying feedforward neural control. Connectome network analyses and simulations identified centralized interneurons forming recurrent excitatory and broad inhibitory circuit motifs that robustly synchronize motor modules. We further validated some model predictions through optogenetic experiments.
Discussion
We identified centralized neural circuits underlying multi-body-part coordination during antennal grooming in flies. Unlike locomotion, where coordination often depends on sensory feedback, grooming synchronization is centrally driven, likely reducing sensory processing demands. We uncovered two neural circuit motifs—recurrent excitation promoting targeted movements, and broadcast inhibition suppressing competing actions—that enable precise yet flexible coordination. This centralized circuit architecture may represent a general neural strategy conserved across behaviors and species, simplifying motor control and facilitating the evolution of complex behaviors through modular coordination.
Acknowledgements PR acknowledges support from an SNSF Project Grant (175667) and an SNSF Eccellenza Grant (181239). JA acknowledges support from a European Research Council Synergy grant (951477). PGO acknowledges support from a Swiss Government Excellence Scholarship for Doctoral Studies and a Google PhD Fellowship.
