Ribeiro, I. M. A. | bioRxiv Science

bioRxiv2026

A multi-input optic glomerulus mediates opposing behavioral responses to visual objects

Prey, predators or conspecifics are first detected as visual objects in many seeing animals. Vision guides behavioral actions towards or away from these objects. An error in this visual perception could prove fatal. How object information is untangled to avoid errors remains unclear. Here we show that LC10d visual projection neurons in Drosophila melanogaster mediate avoidance of visual objects in the absence of a chemosensory profile. LC10d neurons are broadly tuned to objects and project to the same retinorecipient brain region that receives inputs from LC10a neurons, which are required for tracking. The descending neurons DNa10 are directly downstream of the anterior-facing LC10d sub-population and mediate LC10d-dependent avoidance. Our work demonstrates the use of two similar neuron types and chunking of the visual field into zones as strategies to disentangle similar sets of visual cues requiring nearly opposite behavioral responses.

neuroscience↗

bioRxiv2024

Columnar cholinergic neurotransmission onto T5 cells of Drosophila

Several nicotinic and muscarinic acetylcholine receptors (AChRs) are expressed in the brain of Drosophila melanogaster. However, the contribution of different AChRs to visual information processing remains poorly understood. T5 cells are the primary motion-sensing neurons in the OFF pathway and receive input from four different columnar cholinergic neurons, Tm1, Tm2, Tm4 and Tm9. We reasoned that different AChRs in T5 postsynaptic sites might contribute to direction selectivity, a central feature of motion detection. We show that the nicotinic nAChR1, nAChR4, nAChR5 and nAChR7 subunits localize on T5 dendrites. By targeting synaptic markers specifically to each cholinergic input neuron, we find a prevalence of the nAChR5 in Tm1-, Tm2- and Tm4-to-T5 synapses and of nAChR7 in Tm9-to-T5 synapses. Knock-down of nAChR4, nAChR5, nAChR7, or mAChR-B individually in T5 cells alters the optomotor response and reduces T5 directional selectivity. Our findings indicate a differential contribution of postsynaptic receptors to input visual processing and, thus, to the computation of motion direction in T5 cells.

neuroscience↗