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Department of Integrative Biology
University of California, Berkeley
Abstract-
Flies are highly maneuverable organisms that rely on rapid integration of visual
and mechanosensory feedback during flight. The flight paths of the fruit fly,
Drosophila, consist of straight sequences interspersed with rapid saccadic
turns. While flies are thought to rely heavily on visual feedback in flight
control, evidence suggests that the halteres, mechanosensory structures that act
as an inertial guidance system, dominate flight control during the straight
flight sequences. The information from the halteres is transmitted to the motor
system by a phase-variant temporal code that alters the mechanical properties of
steering muscles. Since mechanosensory cells are capable of faster response
dynamics than photoreceptors, feedback from the halteres can tune the stability
reflexes much more accurately than could slower visual feedback. Visual
integration plays a critical role, however, in determining the direction and
timing of saccades. During straight flight, the visual system appears to
integrate optic expansion, triggering a collision avoidance saccade when the
expansion reaches a critical threshold. Further, the visual system may alter the
gain of the equilibrium system by modulating the activity of halter control
muscles. In summary, the rapid maneuverability and robust stability of flies
emerges from this complex interaction of sensory modalities.
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