Visual afferences to flight steering muscles controlling optomotor responses of the fly

Abstract

Summary. In tethered flying house-flies (Musca domestica) visually induced turning reactions weremonitored under open-loop conditions simultaneously with the spike activity of four types of steering muscles (M.bl, M.b2, M.II, M.III1). Specific behavioral response components are attributed to the activity of particular muscles. Compensatory optomotor turning reactions to large-field image displacements mainly occur when the stimulus pattern oscillates at low frequencies. In contrast, turning responses towards objects are preferentially induced by motion of relatively small stimuli at high oscillation frequencies. The different steering muscles seem to be functionally specialized in that they contribute to the control of these behavioral responses in different ways. The muscles I1, IIIl and b2 are preferentially active during small-field motion at high oscillation frequencies. They are much less active during small-field motion at low oscillation frequencies and large-field motion at all oscillation frequencies which were tested. M.b2 is most extreme in this respect. These steering muscles thus mediate :mainly turns towards objects. In contrast, M.bl responds best during large-field motion at low oscillation frequencies and, thus, is appropriate to control compensatory optomotor responses. However, the activity of this muscle is also strongly modulated during small-field motion at high oscillation frequencies and, therefore, may be involved also in the control of turns towards objects. These functional specializations of the different steering muscles in mediating different behavioral ~response components are related to the properties of two parallel visual pathways that are selectively tuned to largefield and small-field motion, respectively.Abbreviations. FD (cell) figure detection (cell); HS (cell) horizontal (cell)

Detection of object motion by a fly neuron during simulated flight

“…Turning responses of the¯y around its vertical body axis are thought to be controlled by two systems in parallel which have di erent dynamical properties (Egelhaaf 1987(Egelhaaf , 1989. Fast object-directed turning behaviour is mediated by the object detection system.…”

Photo-ablation of single neurons in the fly visual system reveals neural circuit for the detection of small moving objects

“…This appears to be all the more interesting as we know the functional context of this circuit. By comparing behavioral responses of tethered flies with the response characteristics of the FDl-cell, the FDl-cell has been concluded to play a decisive role in discriminating moving objects from their background and mediating orientation turns towards them [7,8,11,27]. Hence, the circuit established in the present study is one of the very few examples where it has been possible to link visual orientation behavior to network interactions at the cellular level.…”

Processing of figure and background motion in the visual system of the fly

“…This has been analyzed in various studies by both behavioral and electrophysiological techniques as well as by theoretical means (Poggio et al 1981;Reichardt et al 1983;Hausen 1984;Hausen and Wehrhahn 1983;Egelhaaf 1985aEgelhaaf , 1987Egelhaaf , 1989Egelhaaf et al 1988). The present study exploits the fortunate analytical situation that the LF-and the SF-system have different dynamical properties which allows to stimulate them relatively independently from each other (Egelhaaf 1987).…”