Sexual dimorphism in sensorimotor transformation of insect optic flow

Motion vision underpins a wide range of adaptive behaviours essential for
individual and species survival. In hoverflies, some visual behaviours are
sexually dimorphic, including for example male high-speed pursuit of
conspecifics, matched by improved optics, and faster photoreceptors. Other
visual behaviours are sexually 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 address this, we combined
morphological analysis with electrophysiology of optic flow sensitive
descending neurons and compared neural responses to the behavioural output
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, behavioural responses were noticeably
slower than neural responses. Together, our findings uncover a nuanced,
sex- and stimulus- dependant sensorimotor transformation, shaped by both
neural architecture and behavioural demands.