Turns with multiple and single head cast mediate Drosophila larval light avoidance

Abstract

Drosophila larvae exhibit klinotaxis when placed in a gradient of temperature, chemicals, or light. The larva samples environmental stimuli by casting its head from side to side. By comparing the results of two consecutive samples, it decides the direction of movement, appearing as a turn proceeded by one or more head casts. Here by analyzing larval behavior in a light-spot-based phototaxis assay, we showed that, in addition to turns with a single cast (1-cast), turns with multiple head casts (n-cast) helped to improve the success of light avoidance. Upon entering the light spot, the probability of escape from light after the first head cast was only ~30%. As the number of head casts increased, the chance of successful light avoidance increased and the overall chance of escaping from light increased to >70%. The amplitudes of first head casts that failed in light avoidance were significantly smaller in n-cast turns than those in 1-cast events, indicating that n-cast turns might be planned before completion of the first head cast. In n-casts, the amplitude of the second head cast was generally larger than that of the first head cast, suggesting that larvae tried harder in later attempts to improve the efficacy of light avoidance. We propose that both 1-cast turns and n-cast turns contribute to successful larval light avoidance, and both can be initiated at the first head cast.

Mouse Navigation Strategies for Odor Source Localization

“…Rats employ head oscillations that sweep back and forth across a trail as they track it (Khan et al, 2012), a strategy also used by humans (Porter et al, 2007) and ants (Hangartner, 1969;Draft et al, 2018) following trails. In this study, we use the term 'casting' to describe the amplitude of the movement of the olfactory sensors during navigation toward an odor source (Heitz, 2014;Zhao et al, 2017;Baker et al, 2018).…”

A disinhibitory mechanism biases Drosophila innate light preference

“…The procedure of light spot assay was largely same as previously described 46 . Individual larva was first acclimated on an agar plate for 2 min in a dark room.…”

“…The larval behavioral details in light spot assay were analyzed with a modified version of SOS 46 . In brief, single larva was sketched out from background and thinned to a line by algorithms implanted in matlab (Mathworks Inc.).…”

“…For larval head cast size upon light-on and light-off in light spot assay, the size of head cast upon light-on was defined as previously described with modifications 46 . As larva head cast happened always after deceleration, they were considered as an assembly when we judged the light related events.…”

Neural substrates of navigational decision-making inDrosophilalarva anemotaxis

“…This behavior is essential for survival and is shared across the animal kingdom. Many small organisms navigate their environments and move towards more favorable conditions by biasing their motor decisions as a function of the changes in the sensory information (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). Organisms like C. elegans and larval Drosophila were shown to alternates periods of forward movements with reorientation events during which they make directional changes (decisions).…”