Modality-specific circuits for skylight orientation in the fly visual system

摘要: Abstract In the fly optic lobe ∼800 highly stereotypical columnar microcircuits are arranged retinotopically to process visual information. Differences in cellular composition and synaptic connectivity within functionally specialized columns remains largely unknown. Here we describe architecture medulla located downstream of photoreceptors ‘dorsal rim area’ (DRA), where linearly polarized skylight is detected for guiding orientation responses. We show that only DRA columns, both R7 R8 target bona fide layer they form connections with previously uncharacterized, modality-specific Dm neurons: Two morphologically distinct DRA-specific cell types (termed Dm-DRA1 Dm-DRA2) stratify separate sublayers exclusively contact polarization-sensitive inputs, while avoiding overlaps color-sensitive Dm8 cells. Using activity-dependent GRASP trans-Tango techniques, confirm cells synaptically connected Dm-DRA1, whereas synapses Dm-DRA2. Finally, using live imaging ingrowing pupal photoreceptor axons, termini reach M6 sequentially, thus separating establishment different time. propose a duplication R7→Dm circuitry ommatidia serves as an ideal adaptation detecting orthogonal e-vector analyzers.