Biology subjects

Mathejczyk, T. F.

Publications and source records attributed to Mathejczyk, T. F..

3 recordsLinked to original sources

bioRxiv2019

Heading choices of flying Drosophila under changing angles of polarized light

Many navigating insects include the celestial polarization pattern as an additional visual cue to orient their travels. Spontaneous orientation responses of both walking and flying fruit flies (Drosophila melanogaster) to linearly polarized light have previously been demonstrated. Using newly designed modular flight arenas consisting entirely of off-the-shelf parts and 3D-printed components we present individual flying flies with a slow and continuous rotational change in the incident angle of linear polarization. Under such open-loop conditions, single flies choose arbitrary headings with respect to the angle of polarized light and show a clear tendency to maintain those chosen headings for several minutes, thereby adjusting their course to the slow rotation of the incident stimulus. Importantly, flies show the tendency to maintain a chosen heading even when two individual test periods under a linearly polarized stimulus are interrupted by an epoch of unpolarized light lasting several minutes. Finally, we show that these behavioral responses are wavelength-specific, existing under polarized UV stimulus while being absent under polarized green light. Taken together, these findings provide further evidence supporting Drosophilas abilities to use celestial cues for visually guided navigation and course correction.

neuroscience↗

bioRxiv2019

Modality-specific circuits for skylight orientation in the fly visual system

In the fly optic lobe [~]800 highly stereotypical columnar microcircuits are arranged retinotopically to process visual information. Differences in cellular composition and synaptic connectivity within functionally specialized columns remains largely unknown. Here we describe the cellular and synaptic architecture in medulla columns located downstream of photoreceptors in the dorsal rim area (DRA), where linearly polarized skylight is detected for guiding orientation responses. We show that only in DRA medulla columns, both R7 and R8 photoreceptors target to the bona fide R7 target layer where they form connections with previously uncharacterized, modality-specific Dm neurons: Two morphologically distinct DRA-specific cell types (termed Dm-DRA1 and Dm-DRA2) stratify in separate sublayers and exclusively contact polarization-sensitive DRA inputs, while avoiding overlaps with color-sensitive Dm8 cells. Using the activity-dependent GRASP and trans-Tango techniques, we confirm that DRA R7 cells are synaptically connected to Dm-DRA1, whereas DRA R8 form synapses with Dm-DRA2. Finally, using live imaging of ingrowing pupal photoreceptor axons, we show that DRA R7 and R8 termini reach layer M6 sequentially, thus separating the establishment of different synaptic connectivity in time. We propose that a duplication of R7[->]Dm circuitry in DRA ommatidia serves as an ideal adaptation for detecting linearly polarized skylight using orthogonal e-vector analyzers.

neuroscience↗

bioRxiv2019

New modular assays for the quantitative study of skylight navigation in flying flies

The quantitative study of visual behaviors using virtual flight arenas is complicated by the fact that an effective experimental setup needs to combine a rather complex set of custom-built mechanical, electronic, and software components. Assembling such an apparatus amounts to a major challenge when working in an environment without the support of a machine shop. Here we present detailed instructions for the assembly of virtual flight arenas optimized for Drosophila skylight navigation, which can easily be modified towards other uses. This system consists entirely of off-the-shelf parts and 3D-printed components, combining a modular flight arena designed to reduce visual artifacts, swappable high-power LED light sources, polarization filters on a computer-controlled rotating filter wheel, all placed within a temperature and humidity controlled environment. Using this new assay, we show that individual flies choose arbitrary headings when flying under a uniform field of linear polarization. Furthermore, flies adjust their heading to both sudden and continuous changes in filter orientation and can keep their chosen heading for several minutes. Finally, flies show the tendency to maintain headings even after interruption with an unpolarized stimulus. Taken together, these findings demonstrate the usefulness of these assays for the study of skylight navigation in flies.

neuroscience↗