Biology subjects

Mathejczyk, T. F.

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

6 recordsLinked to original sources

bioRxiv2026

A minimal visual world model predicts exploration of naturalistic landscapes in flies

Animals, including small insects, can explore complex natural environments to locate resources and potential mates. How a miniaturized nervous system extracts actionable structure from complex visual scenes to guide effective exploration remains incompletely understood. To bridge the gap between behavioristic experimental control and ethological realism, we combined a virtual-reality flight assay with naturalistic three-dimensional environments based on high-resolution satellite imagery of real-world landscapes. Flies that had never experienced natural environments exhibited individually stable, non-random exploration patterns and preferred flying over vegetated and elevated terrain while avoiding water-like features, indicative of a minimalistic world model for ecologically relevant terrain selection. Flight paths were characterized by saccadic turns, which we analyzed in relation to visual scene components, including brightness, color composition, optic flow, elevation, and contrast. Using multivariable regression modeling, we identified a hierarchy of visual cues influencing saccade frequency, amplitude, and directionality, and mapped the retinal areas most strongly gating saccadic decision-making. We discovered individual differences in motion-sensitivity thresholds that predict stable individual exploration-exploitation phenotypes. indicating a population-level bet-hedging strategy to increase terrain coverage and resource encounter rates. Individuality-based probabilistic decision-making simulations, utilizing our hierarchical visual models, successfully replicated exploration behavior, with the predicted dispersal and trajectory statistics matching the empirical data and demonstrating generality even for visual assays not included in the training dataset. Our work links individual visual decision rules to efficient exploration mechanisms of large-scale natural landscapes, potentially inspiring neural circuit theory, ecological prediction frameworks, vision-based pest control, and energy-efficient autonomous system design.

neuroscience↗

bioRxiv2022

Behavioral responses of free flying Drosophila melanogaster to shiny, reflecting surfaces

Active locomotion plays an important role in the life of many animals since it permits to explore the environment and find vital resources. Most insect species rely on a combination of visual cues such as celestial bodies, landmarks, or linearly polarized light to navigate or to orient themselves in their surroundings. In nature, linearly polarized light can arise either from atmospheric scattering or from reflections off shiny non-metallic surfaces like water or shiny foil. Although multiple reports described different behavioral responses of various insects to such shiny surfaces, little is known about the retinal detectors or the underlying neural circuits. Our goal was to quantify the behavioral responses of free flying Drosophila melanogaster, a molecular genetic model organism that allows for systematic dissection of neural circuitry. Fruit flies were placed in a custom-built arena with controlled environmental parameters (temperature, humidity, and light intensity). Flight densities and landings were quantified for hydrated and dehydrated fly populations when separately exposed to three different stimuli such as a diffusely-reflecting matt plate, a small patch of shiny foil, versus real water. Our analysis reveals for the first time that flying fruit flies indeed use vision to guide their flight maneuvers around shiny surfaces.

animal behavior and cognition↗

bioRxiv2020

Systematic functional analysis of Rab GTPasesreveals limits of neuronal robustness in Drosophila

Rab GTPases are molecular switches that regulate membrane trafficking in all cells. Neurons have particular demands on membrane trafficking and express numerous Rab GTPases of unknown function. Here we report the generation and characterization of molecularly defined null mutants for all 26 rab genes in Drosophila. In addition, we created a transgenic fly collection for the acute, synchronous release system RUSH for all 26 Rabs. In flies, all rab genes are expressed in the nervous system where at least half exhibit particularly high levels compared to other tissues. Surprisingly, loss of any of these 13 nervous-system enriched Rabs yields viable and fertile flies without obvious morphological defects. However, 9 of these 13 affect either developmental timing when challenged with different temperatures, or neuronal function when challenged with continuous stimulation. These defects are non-lethal under laboratory conditions, but represent sensitized genetic backgrounds that reveal limits of developmental and functional robustness to environmental challenges. Interestingly, the neuronal rab26 was previously proposed to function in synaptic maintenance by linking autophagy and synaptic vesicle recycling and we identified rab26 as one of six rab mutants with reduced synaptic function under continuous stimulation conditions. However, we found no changes to autophagy or synaptic vesicle markers in the rab26 mutant, but instead a cell-specific role in membrane receptor turnover associated with cholinergic synapses in the fly visual system. Our systematic functional analyses suggest that several Rabs ensure robust development and function under varying environmental conditions. The mutant and transgenic fly collections generated in this study provide a basis for further studies of Rabs during development and homeostasis in vivo.

neuroscience↗

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↗