Characterisation of a blowfly male-specific neuron using behaviourally generated visual stimuli

Abstract

The pursuit system controlling chasing behaviour in male blowXies has to cope with extremely fast and dynamically changing visual input. An identiWed male-speciWc visual neuron called Male Lobula Giant 1 (MLG1) is presumably one major element of this pursuit system. Previous behavioural and modelling analyses have indicated that angular target size, retinal target position and target velocity are relevant input variables of the pursuit system. To investigate whether MLG1 speciWcally represents any of these visual parameters we obtained in vivo intracellular recordings while replaying optical stimuli that simulate the visual signals received by a male Xy during chasing manoeuvres. On the basis of these naturalistic stimuli we Wnd that MLG1 shows distinct direction sensitivity and is depolarised if the target motion contains an upward component. The responses of MLG1 are jointly determined by the retinal position, the speed and direction, and the duration of target motimotion. Coherence analysis reveals that although retinal target size and position are in some way inherent in the responses of MLG1, we Wnd no conWrmation of the hypothesis that MLG1 encodes any of these parameters exclusively.

A Network of Visual Motion-Sensitive Neurons for Computing Object Position in an Arthropod

“…As for object motion, different cell classes known as male lobula giants have been described in male flies, but these are all sensitive to a restricted visual field area (Strausfeld, 1991;Trischler et al, 2007). To our knowledge, a representation of the whole visual field by neurons sensitive to object motion has not been hitherto described in any arthropod.…”

Neuronal representation of visual motion and orientation in the fly medulla

“…Thus, the medulla is a good candidate neuropil to extract these visual features from local input and to supply this information to more specialized downstream brain regions. The large lobula plate neurons, which integrate local motion inputs and thus respond in a direction-selective way to motion in a large part of the visual field have been studied extensively (Borst et al, 2010), and some types of neurons of the lobula have been characterized (Gilbert and Strausfeld, 1991; Nordstrom et al, 2006; Okamura and Strausfeld, 2007; Trischler et al, 2007). In contrast, hampered by the small size of the neurons in the medulla, the neural substrates of local motion or shape detection are still enigmatic although detailed accounts of the anatomical structure of the medulla exist for Drosophila (Fischbach and Dittrich, 1989) and Musca (Strausfeld, 1976).…”

Neuronal encoding of object and distance information: a model simulation study on naturalistic optic flow processing

“…In contrast, when hunting a prey or chasing after a potential mate, insects are required to detect and pursue extremely small moving objects. In the visual system of dragonflies and several fly species, specialized neurons have been concluded to play a role in such tasks (Olberg, 1981, 1986; Gilbert and Strausfeld, 1991; Strausfeld, 1991; Wachenfeld, 1994; Nordström et al, 2006; Nordström and O'Carroll, 2006; Barnett et al, 2007; Geurten et al, 2007; Trischler et al, 2007). These neurons differ tremendously from the FD1 cell: They are highly selective to objects that are smaller than the interommatidial angle, even if they move in front of a cluttered background.…”

“…These properties presumably play a role in predatory or chasing behavior for mates (Collett and Land, 1975; Wehrhahn, 1979; Wehrhahn et al, 1982; Zeil, 1983; Olberg et al, 2000; Boeddeker et al, 2003; Trischler et al, 2010). Pursuit, especially in the case of mating behavior, is thought to be mediated by male-specific visual neurons sensitive to small targets (Gilbert and Strausfeld, 1991; Strausfeld, 1991; Wachenfeld, 1994; Trischler et al, 2007), but not by the FD1 cell that has been characterized in females and is not sufficiently sensitive to extremely small objects.…”