Biology subjects

Stoeckl, A.

Publications and source records attributed to Stoeckl, A..

4 recordsLinked to original sources

bioRxiv2025

A connectomics-based analysis of lamina monopolar cells reveals mechanisms of spatial processing in insect motion vision

Many animals strongly rely on their sense of vision, as it provides information about the natural world with particularly high dimensionality. In insects, the first visual processing stage of the brain, the lamina, plays an important role in parallel processing of this complex information. Its main relay neurons, lamina monopolar cells (LMCs), receive information directly from the photoreceptors and shape the contrast, luminance, spatial and temporal tuning of the insect visual system in a cell-type specific manner. One of their best-investigated downstream targets is the motion vision pathway. However, how LMC types that feed into motion processing delineate contrast and luminance is only known from fruit flies, while the contribution of LMCs to spatial processing has only been described in hawkmoths. Here, we provide a novel characterization of hawkmoths lamina monopolar cells, to integrate the contrast, luminance and spatial processing properties of LMCs in the motion pathway. We used serial block-face scanning electron microscopy to reconstruct the anatomical fine structure of LMCs in a focal lamina cartridge, including their pre- and post-synaptic connections. Combining our novel LMC classification with intracellular recordings, we further investigated the functional role of the main relay neurons to the motion pathway, L1 and L2, in terms of contrast and spatial processing. We show that unlike in flies, L1 and L2 process contrast, and spatial information similarly. Crucially, their two distinct spatial processing functions, lateral inhibition and spatial summation are explained by the density and distribution of their synapses in different lamina layers. Based on these findings, we propose a novel mechanism of delineating distinct spatial processing functions in a single cell.

neuroscience↗

bioRxiv2024

Bumblebees flexibly adjust learning and decision strategies to sensory information content in a foraging task

When making decisions, humans and animals often rely on multiple sensory cues simultaneously. These provide complementary sources of information, which can help overcome ambiguity and noise, and increase the accuracy of decisions. While most studies have focused on the benefits of multimodal and within-mode integration for learning and decision making, their costs have received less attention. Processing, learning and memorizing multiple inputs requires more neural resources than for single cues, and might also require more time. In this study, we tested whether insects trade off the costs and benefits of learning multiple cues in a foraging task, using the buff-tailed bumblebee Bombus terrestris. To maximize comparability between cues, we presented combinations of visual-only features, as found on natural flowers: colours of varying discriminability, paired with shapes or patterns. We found that the bees relied exclusively on colours when these were easy to discriminate, and did not learn pattern or shape features presented simultaneously. With harder to discriminate colours, the bees learned both colour and shape or pattern features. Our results demonstrate that bumblebees flexibly adjust their learning strategies when presented with visual features of varying discriminability, to balance the costs and benefits of multi-cue learning. Our analysis of the learning rates of the bees with multi- and single attribute stimuli suggests that blocking could serve as a mechanism to implement this strategy switch. These results shed light on trade-offs in learning and decision making with multiple cues, and can directly be compared to studies in other insects, animals and humans. Significance StatementWhen making decisions, animals often rely on multiple sensory cues simultaneously. These complementary sources of information can increase decision accuracy. Unlike the benefits of cue integration, their costs have received less attention. In this study, we tested whether insects trade off the costs and benefits of learning multiple cues in a foraging task. We trained buff-tailed bumblebees, Bombus terrestris, to feature combinations of natural flowers. Bees flexibly switched from linear integration to winner-takes-all decision strategies depending on the sensory information available, thereby balancing accuracy and time investment in the task. We find that this switch can be explained by the cognitive phenomenon of blocking; providing the ground for future investigations into the underlying neural mechanisms of flexible decision strategies.

animal behavior and cognition↗

bioRxiv2024

Integration of parallel pathways for flight control in a hawkmoth reflects prevalence and relevance of natural visual cues

An animals behaviour is the result of multiple neural pathways acting in parallel, receiving information across and within sensory modalities at the same time. How these pathways are integrated, particularly when their individual outputs are in conflict, is key to understanding complex natural behaviours. We investigated this question in the visually guided flight of the hummingbird hawkmoth Macroglossum stellatarum. These insects were recently shown to partition their visual field, using ventrolateral optic-flow cues to guide their flight like most insects, while the same stimuli in the dorsal visual field evoke a novel directional response. Using behavioural experiments which set the two pathways into conflict, we tested whether and how the ventrolateral and dorsal pathway integrate to guide hawkmoth flight. Combined with environmental imaging we demonstrate that the partitioning of the visual field followed the prevalence of visual cues in the hawkmoths natural habitats, while the integration hierarchy of the two pathways matched the relevance of these cues for the animals flight safety, rather than their magnitude in the experimental setup or in natural habitats. These results provide new mechanistic insights into the vision-based flight control of insects, and link these to their natural context. We anticipate our findings to be the starting point for comparative investigations into parallel pathways for flight guidance in insects from differently structured natural habitats.

animal behavior and cognition↗

bioRxiv2018

Independent control of slow and fast flight manoeuvres in insects: the roles of vision and antennal mechanoreception

Flying animals need constant sensory feedback about their body position and orientation for flight control. The visual system provides essential but slow feedback. In contrast, mechanosensory channels can provide feedback at much shorter timescales. How the contributions from these two senses are integrated remains an open question in most insect groups. In Diptera, fast mechanosensory feedback is provided by organs called halteres, and is crucial for the control of rapid flight manoeuvres, while vision controls manoeuvres in lower temporal frequency bands. Here we have investigated the visual-mechanosensory integration in an insect which lacks halteres: the hawkmoth Macroglossum stellatarum. They represent a large group of insects that use Johnstons organs in their antennae to provide mechanosensory feedback on perturbations in body position. High-speed videos of freely-flying hawkmoths hovering at stationary or oscillating artificial flowers showed that positional fidelity during flight was reduced in flagella ablated animals, but was recovered after flagella re-attachment. Our experiments show that antennal mechanosensory feedback specifically mediates fast flight manoeuvres, but not slow ones. Differences in the latency of visual feedback (in different light intensities) affected all antennal conditions equally, suggesting there was no compensatory interaction between antennal and visual feedback under the tested conditions. These results establish the importance of antennal mechanosensors in providing rapid mechanosensory feedback for finer control of flight manoeuvres, acting in parallel to visual feedback.

neuroscience↗