Sexual dimorphism in sensorimotor transformation of optic flow

Motion vision underpins a wide range of adaptive behaviours essential for individual and species survival. Some visual behaviours are sexually dimorphic, including for example male hoverfly high-speed pursuit of conspecifics, matched by improved optics, and faster photoreceptors. Other visual behaviours are monomorphic, with for example similar foraging flight speeds in male and female hoverflies. However, whether the descending neurons responsible for sensorimotor transformation of optic flow are sexually dimorphic is unknown. To redress this, we combined morphological analysis with electrophysiology of optic flow sensitive descending neurons and compared neural responses to the wing beat amplitude in tethered hoverflies. We found that while optomotor flight behaviour is largely sexually monomorphic, the underlying neural responses are sexually dimorphic, especially at higher optic flow velocities. Additionally, neural and behavioural responses to roll stimuli had a slower onset compared to lift, revealing stimulus specific encoding. Together, our findings uncover a nuanced, sex- and stimulus- dependant sensorimotor transformation, shaped by both neural architecture and behavioural demands.