| 1. |
- Dahake, Ajinkya, et al.
(författare)
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The roles of vision and antennal mechanoreception in hawkmoth flight control
- 2018
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Ingår i: eLife. - 2050-084X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Flying animals need continual 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 the hawkmoth Macroglossum stellatarum. They represent a large group of insects that use Johnston's organs in their antennae to provide mechanosensory feedback on perturbations in body position. Our experiments show that antennal mechanosensory feedback specifically mediates fast flight manoeuvres, but not slow ones. Moreover, we did not observe compensatory interactions between antennal and visual feedback.
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| 2. |
- Gilmour, Kathleen M., et al.
(författare)
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Through the looking glass : attempting to predict future opportunities and challenges in experimental biology
- 2023
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Ingår i: The Journal of experimental biology. - 1477-9145. ; 226:24
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Tidskriftsartikel (refereegranskat)abstract
- To celebrate its centenary year, Journal of Experimental Biology (JEB) commissioned a collection of articles examining the past, present and future of experimental biology. This Commentary closes the collection by considering the important research opportunities and challenges that await us in the future. We expect that researchers will harness the power of technological advances, such as '-omics' and gene editing, to probe resistance and resilience to environmental change as well as other organismal responses. The capacity to handle large data sets will allow high-resolution data to be collected for individual animals and to understand population, species and community responses. The availability of large data sets will also place greater emphasis on approaches such as modeling and simulations. Finally, the increasing sophistication of biologgers will allow more comprehensive data to be collected for individual animals in the wild. Collectively, these approaches will provide an unprecedented understanding of 'how animals work' as well as keys to safeguarding animals at a time when anthropogenic activities are degrading the natural environment.
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| 3. |
- Natesan, Dinesh
(författare)
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Neuromechanical basis of airflow-dependent antennal positioning in hawkmoths
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fast behaviors, seen in varied life forms, are often considered to be stereotypic and reflexive and the control neural circuits to be hard-wired. However, many such reflexes have been shown to respond in a context-dependent manner. The work presented in this dissertation focuses on uncovering the principles of one such context-dependent behavior - antennal positioning in insects.Insect antennae acquire multimodal sensory cues that are required for a wide range of behaviors. These include odor, temperature, humidity, as well as mechanical vibrations from the surroundings. Each modality encodes a different aspect of the environment and is used appropriately to control behavior. Antennal vibrations, for instance, provide feedback relevant for flight stabilization, and is used to modulate wing movements on short, stroke-to-stroke, timescales. Olfactory cues, on the other hand, indicate presence of food and mates, and are used to alter flight trajectories over longer timescales of multiple wing-strokes. Therefore, for a proper behavioral response, the antennae must optimally acquire sensory cues over multiple timescales. Context-dependent modulation of the antennae perhaps enhances their functionality by tuning their dynamic range.This dissertation focuses on one context, namely airflow, and its effect on antennal positioning. Hawkmoths, and diverse insects, actively position their antennae at the onset of flight by bringing them forward. During flight, they dynamically alter this position based on airflow. Two antennal mechanosensors are involved in this behavior, one being the Böhm’s bristles, which monitors and feeds back the position of the antennae, and the second being the Johnston’s organs, which are stimulated by frontal airflow generated during flight.The first part of the thesis concerns the control algorithms that underlie the sensory integration of antennal mechanosensory input to produce airflow-dependent antennal positioning. Using the Oleander hawkmoth, Daphnis nerii, as a system of study, the behavior is investigated with a combination of experiments and computational techniques. We find that the dynamics of this behavior can be captured by a tunable feedback loop consisting of two components. One, a negative feedback loop that stably maintains antennae at a preferred position, or set-point, using positional feedback from the Böhm’s bristles. Two, a dynamic set-point that is modulated by airflow (and other context specific cues). Furthermore, a minimalistic model neural circuit based on these components simulate airflow-dependent modulation of antennae. Such circuits could enable moths to maintain stable antennal position on short timescales while retaining context-based flexibility over longer durations.The latter half of the thesis focuses on each of the individual components. The neural mechanisms underlying modulation of set-point by the Johnston’s organs are investigated using behavioral and electrophysiological experiments. The positional feedback, sensed and encoded by the Böhm’s bristles, is investigated using biomechanical models. These provide an understanding of how airflow-dependent, or more generally, context-dependent antennal positioning arises as a result of these individual components. As a whole, this dissertation provides a conceptual framework that utilizes experimental and computational techniques to formally describe and understand context-dependent behaviors.
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| 4. |
- Natesan, Dinesh, et al.
(författare)
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Tuneable reflexes control antennal positioning in flying hawkmoths
- 2019
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Complex behaviours may be viewed as sequences of modular actions, each elicited by specific sensory cues in their characteristic timescales. From this perspective, we can construct models in which unitary behavioural modules are hierarchically placed in context of related actions. Here, we analyse antennal positioning reflex in hawkmoths as a tuneable behavioural unit. Mechanosensory feedback from two antennal structures, Bohm's bristles (BB) and Johnston's organs (JO), determines antennal position. At flight onset, antennae attain a specific position, which is maintained by feedback from BB. Simultaneously, JO senses deflections in flagellum-pedicel joint due to frontal airflow, to modulate its steady-state position. Restricting JO abolishes positional modulation but maintains stability against perturbations. Linear feedback models are sufficient to predict antennal dynamics at various set-points. We modelled antennal positioning as a hierarchical neural-circuit in which fast BB feedback maintains instantaneous set-point, but slow JO feedback modulates it, thereby elucidating mechanisms underlying its robustness and flexibility.
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| 5. |
- Saxena, Nitesh, et al.
(författare)
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Odor source localization in complex visual environments by fruit flies
- 2018
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Ingår i: Journal of Experimental Biology. - : Company Of Biologists LTD. - 0022-0949 .- 1477-9145. ; 221:2
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Tidskriftsartikel (refereegranskat)abstract
- Flying insects routinely forage in complex and cluttered sensory environments. Their search for a food or a pheromone source typically begins with a whiff of odor, which triggers a flight response, eventually bringing the insect near the odor source. However, pinpointing the precise location of an odor source requires use of both visual and olfactory modalities, aided by odor plumes. Here, we investigated odor-tracking behavior in fruit flies (Drosophila melanogaster) presented with low-or high-contrast visual landmarks, either paired with or separate from an attractive odor cue. These experiments were conducted either in a gentle air stream which generated laminar odor plumes or in still air in which odor dissipates uniformly in all directions. Trajectories of flies revealed several novel features of their odor-tracking behavior in addition to those previously documented. First, in both moving and still air, odor-seeking flies rely on the co-occurrence of visual landmarks with olfactory cues to guide them to odorant objects. Second, flies abruptly decelerate upon encountering an odor plume, thereafter steering towards the nearest visual objects that had no inherent salience in the absence of odor. Thus, interception of an attractive odor increases their salience to nearby high-contrast visual landmarks. Third, flies adopt distinct odor-tracking strategies during flight in moving versus still air. Whereas they weave in and out of plumes towards an odor source in airflow, their approach is more incremental in still air. Both strategies are robust and flexible, and enable flies to reliably find odor sources under diverse visual and airflow environments.
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