Connectome analysis reveals brain-wide processing of visual features in Drosophila

Sensory processing relies on an intricate interplay between specialized sensory circuits and the broader brain. Leveraging the whole-brain Drosophila melanogaster connectome, we analyzed long-range projections linking the optic lobe (OL)--the principal visual center--reciprocally with the central brain and the contralateral OL to determine how visual features are computed by a brainwide network. By quantifying synaptic polarity and connectivity, we classified the projection neurons into feedforward, feedback, and bilateral groups. Feedforward neurons form an information bottleneck, consolidating diverse visual features from the OL and distributing them through modular pathways for higher-order processing. Feedback neurons densely innervate OL structures, conveying contextual signals in the central brain via precise recurrent loops. Bilateral neurons link local visual circuits across the two OLs, providing a substrate for inter-ocular processing. These findings reveal how early visual pathways interface with brainwide circuits to support diverse brain functions and enable context-dependent flexibility in sensory computation. HighlightsO_LIWhole-brain connectome analysis identifies three streams of brainwide visual processing C_LIO_LIFeedforward neurons form a bottleneck and distribute features for higher processing C_LIO_LIFeedback neurons modulate early vision via layer-specific recurrent loops C_LIO_LIBilateral neurons bridge both optic lobes to enable inter-ocular processing C_LI