Sexual dimorphism in the hoverfly motion vision pathway.
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.
Nordström
Karin
K
Discipline of Physiology, School of Molecular and Biomedical Science, The University of Adelaide, SA, Australia. karin.nordstrom@adelaide.edu.au
Barnett
Paul D
PD
Moyer de Miguel
Irene M
IM
Brinkworth
Russell S A
RS
O'Carroll
David C
DC
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