title: Sexual dimorphism in the hoverfly motion vision pathway.
abstract: Many insects perform high-speed aerial maneuvers in which they navigate through visually complex surrounds. Among insects, hoverflies stand out, with males switching from stationary hovering to high-speed pursuit at extreme angular velocities [1]. In dipterans, 50-60 large interneurons -- the lobula-plate tangential cells (LPTCs) -- detect changes in optic flow experienced during flight [2-5]. It has been predicted that large LPTC receptive fields are a requirement of accurate "matched filters" of optic flow [6]. Whereas many fly taxa have three horizontal system (HS) LPTC neurons in each hemisphere, hoverflies have four [7], possibly reflecting the more sophisticated flight behavior. We here show that the most dorsal hoverfly neuron (HS north [HSN]) is sexually dimorphic, with the male receptive field substantially smaller than in females or in either sex of blowflies. The (hoverfly-specific) HSN equatorial (HSNE) is, however, sexually isomorphic. Using complex optic flow, we show that HSN, despite its smaller receptive field, codes yaw velocity as well as HSNE. Responses to a target moving against a plain or textured background suggest that the male HSN could potentially play a role in target pursuit under some conditions.
authors.affiliation: Discipline of Physiology, School of Molecular and Biomedical Science, The University of Adelaide, SA, Australia. karin.nordstrom@adelaide.edu.au
authors.forename: Karin
authors.initials: K
authors.lastname: Nordström
authors.forename: Paul D
authors.initials: PD
authors.lastname: Barnett
authors.forename: Irene M
authors.initials: IM
authors.lastname: Moyer de Miguel
authors.forename: Russell S A
authors.initials: RS
authors.lastname: Brinkworth
authors.forename: David C
authors.initials: DC
authors.lastname: O'Carroll
mesh_terms: D000818:Animals; D004175:Diptera / Q000502:physiology*; D005260:Female; D005426:Flight, Animal / Q000502:physiology; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000166:cytology*; D009899:Optic Lobe, Nonmammalian / Q000166:cytology*; D012727:Sex Characteristics