The functional organization of male-specific visual neurons in flies

Abstract

Intracellular recording and Lucifer yellow dye filling of male fleshflies, Sarcophaga bullata, have revealed male-specific neurons in the lobula, the axons of which project to the origin of premotor channels supplying flight motor neurons. Dendrites of male-specific neurons visit areas of the retinotopic mosaic supplied by the retina's acute zone, which is used by males to keep the image of a conspecific female centered during aerial pursuit. Only males engage in high-speed aerobatic chases, and male-specific neurons are suspected to underlie this behavior. Physiological determination of receptive fields of male-specific neurons substantiates the fields predicted from anatomical studies and demonstrates that they subtend the acute zone. Male-specific neurons respond in a manner predicted on theoretical grounds from observations of tracking behavior. Such properties include directional selectivity to visual motion and higher sensitivity to motion of small images than to wide-field motion. The present account substantiates and extends neuroanatomical evidence that predicts that male-specific lobula neurons comprise a distinct circuit mediating conspecific tracking.

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

“…1b). Since the MLG neurons have already been characterised anatomically before (Gilbert and Strausfeld 1991;Gronenberg and Strausfeld 1991;Strausfeld 1991;Wachenfeld 1994), we refrained from a three-dimensional reconstruction.…”

“…After the experiment, the Xy's brain (whole mount) was viewed through a Xuorescence microscope (Leitz, Wetzlar, Germany) and the Wlled cell was photographed in vivo with a digital camera. Only cells, which could be unambiguously identiWed in the whole mount preparation on the basis of prior detailed neuroanatomical studies (Gilbert and Strausfeld 1991;Strausfeld 1991;Wachenfeld 1994), were used for further analysis.…”

“…We test this hypothesis for one of the 12 types of large male-speciWc visual interneurons (MLG, Male Lobula Giant neuron) that have been identiWed in the lobula of Calliphora and Sarcophaga (Gilbert and Strausfeld 1991;Strausfeld 1991). These male-speciWc neurons (MLGs) are most likely the neuronal substrate mediating chasing behaviour (e.g.…”

“…These male-speciWc neurons (MLGs) are most likely the neuronal substrate mediating chasing behaviour (e.g. Hausen and Strausfeld 1980;Gilbert and Strausfeld 1991;Wachenfeld 1994). MLGs terminate on descending neurons, which descend to the thoracic ganglia and have connections with neck and Xight motor neurons (Gronenberg and Strausfeld 1991).…”

“…MLGs terminate on descending neurons, which descend to the thoracic ganglia and have connections with neck and Xight motor neurons (Gronenberg and Strausfeld 1991). Regarding physiology, the MLG1 neuron is best investigated so far: it exhibits pronounced direction selectivity, its receptive Weld subtends the area of the acute zone, and it responds well to small moving objects (Gilbert and Strausfeld 1991;Wachenfeld 1994). Anatomical and physiological characteristics resembling those of MLGs are also described for neurons (STMD, Small Target Motion Detector) found in the lobula of the male hoverXy Eristalis (Nordström et al 2006).…”