scholarly journals A population of descending neurons that regulate the flight motor of Drosophila

2021 ◽  
Author(s):  
Shigehiro Namiki ◽  
Ivo G. Ros ◽  
Carmen Morrow ◽  
William J. Rowell ◽  
Gwyneth M Card ◽  
...  
Keyword(s):  
Flight Control ◽  
Visual Motion ◽  
Dynamic Range ◽  
Critical Set ◽  
Wing Motion ◽  
Descending Neurons ◽  
The Neural Network ◽  
Stable Path ◽  
Bilateral Differences ◽  
Flight Motor

Like many insect species, Drosophila melanogaster are capable of maintaining a stable flight trajectory for periods lasting up to several hours(1, 2). Because aerodynamic torque is roughly proportional to the fifth power of wing length(3), even small asymmetries in wing size require the maintenance of subtle bilateral differences in flapping motion to maintain a stable path. Flies can even fly straight after losing half of a wing, a feat they accomplish via very large, sustained kinematic changes to the both damaged and intact wings(4). Thus, the neural network responsible for stable flight must be capable of sustaining fine-scaled control over wing motion across a large dynamic range. In this paper, we describe an unusual type of descending neurons (DNg02) that project directly from visual output regions of the brain to the dorsal flight neuropil of the ventral nerve cord. Unlike most descending neurons, which exist as single bilateral pairs with unique morphology, there is a population of at least 15 DNg02 cell pairs with nearly identical shape. By optogenetically activating different numbers of DNg02 cells, we demonstrate that these neurons regulate wingbeat amplitude over a wide dynamic range via a population code. Using 2-photon functional imaging, we show that DNg02 cells are responsive to visual motion during flight in a manner that would make them well suited to continuously regulate bilateral changes in wing kinematics. Collectively, we have identified a critical set of DNs that provide the sensitivity and dynamic range required for flight control.

Integration of nonphaselocked exteroceptive information in the control of rhythmic flight in the locust

1985 ◽  
Vol 53 (5) ◽  
pp. 1201-1218 ◽  
Author(s):  
H. Reichert ◽  
C. H. Rowell
Keyword(s):  
Motor Activity ◽  
Flight Control ◽  
Sensory Input ◽  
Sensory Information ◽  
Short Latency ◽  
Synaptic Potentials ◽  
Direct Pathway ◽  
Descending Neurons ◽  
Flight Motor ◽  
Synaptic Effects

The integration of exteroceptive information in the flight control system of the locust was studied by determining the cellular basis of ocellar- (simple eye) mediated control of flight. Neural interactions that transform phase-independent sensory input into phase-specific motor output were characterized. Ocellar information about course deviations during flight was conveyed to the segmental thoracic ganglia by three pairs of large fast multimodal descending neurons. These made connections with thoracic motoneurons directly, via short-latency mono-or disynaptic pathways, and indirectly, via a population of intercalated thoracic interneurons. The synaptic potentials caused in the motoneurons by the direct pathway occurred at short latency and were adequate for summation with other types of sensory input. However, the strength of the synaptic effects of this pathway was weak compared with the central flight oscillator drive to the same motoneurons. In contrast, synaptic potentials evoked by the descending neurons in the thoracic interneurons were often large and brought these cells close to threshold. In turn, these interneurons always had stronger synaptic effects on postsynaptic flight motoneurons than did the descending neurons alone. We conclude that the indirect interneuronal pathway is more powerful in its effects on motoneurons than the direct pathway. Premotor thoracic interneurons, which received ocellar input appropriate for a role in correctional steering, were also rhythmically modulated during flight motor activity in phase with either depressor or elevator motoneurons. This phasic modulatory drive occurred in deafferented preparations, indicating that its source is the central oscillator for flight. Presentation of ocellar stimulation during flight motor activity showed that the central oscillatory modulation of the thoracic interneurons gated the transmission of sensory information through these interneurons. Ocellar-mediated postsynaptic potentials influenced the firing of thoracic interneurons only if they arrived during the proper phase of rhythmic drive. Thus the transmission of ocellar information from interneuron to motor neuron is possible only during appropriate phases of the flight cycle.

scholarly journals Active vision shapes and coordinates flight motor responses in flies

2020 ◽  
Vol 117 (37) ◽  
pp. 23085-23095 ◽  
Author(s):  
Benjamin Cellini ◽  
Jean-Michel Mongeau
Keyword(s):  
Visual Information ◽  
Visual Motion ◽  
Dynamic Range ◽  
Active Vision ◽  
Head Movements ◽  
Tight Coupling ◽  
Motion Vision ◽  
Body Movements ◽  
Motor Responses ◽  
Flight Motor

Animals use active sensing to respond to sensory inputs and guide future motor decisions. In flight, flies generate a pattern of head and body movements to stabilize gaze. How the brain relays visual information to control head and body movements and how active head movements influence downstream motor control remains elusive. Using a control theoretic framework, we studied the optomotor gaze stabilization reflex in tethered flight and quantified how head movements stabilize visual motion and shape wing steering efforts in fruit flies (Drosophila). By shaping visual inputs, head movements increased the gain of wing steering responses and coordination between stimulus and wings, pointing to a tight coupling between head and wing movements. Head movements followed the visual stimulus in as little as 10 ms—a delay similar to the human vestibulo-ocular reflex—whereas wing steering responses lagged by more than 40 ms. This timing difference suggests a temporal order in the flow of visual information such that the head filters visual information eliciting downstream wing steering responses. Head fixation significantly decreased the mechanical power generated by the flight motor by reducing wingbeat frequency and overall thrust. By simulating an elementary motion detector array, we show that head movements shift the effective visual input dynamic range onto the sensitivity optimum of the motion vision pathway. Taken together, our results reveal a transformative influence of active vision on flight motor responses in flies. Our work provides a framework for understanding how to coordinate moving sensors on a moving body.

scholarly journals A chordwise offset of the wing-pitch axis enhances rotational aerodynamic forces on insect wings: a numerical study

2019 ◽  
Vol 16 (155) ◽  
pp. 20190118 ◽  
Author(s):  
Wouter G. van Veen ◽  
Johan L. van Leeuwen ◽  
Florian T. Muijres
Keyword(s):  
Flight Control ◽  
Numerical Study ◽  
Force Production ◽  
Aerodynamic Forces ◽  
Rotational Force ◽  
Wing Motion ◽  
Forward Stroke ◽  
Insect Wings ◽  
Force Mechanism ◽  
Numerical Parametric Study

Most flying animals produce aerodynamic forces by flapping their wings back and forth with a complex wingbeat pattern. The fluid dynamics that underlies this motion has been divided into separate aerodynamic mechanisms of which rotational lift, that results from fast wing pitch rotations, is particularly important for flight control and manoeuvrability. This rotational force mechanism has been modelled using Kutta–Joukowski theory, which combines the forward stroke motion of the wing with the fast pitch motion to compute forces. Recent studies, however, suggest that hovering insects can produce rotational forces at stroke reversal, without a forward motion of the wing. We have conducted a broad numerical parametric study over a range of wing morphologies and wing kinematics to show that rotational force production depends on two mechanisms: (i) conventional Kutta–Joukowski-based rotational forces and (ii) a rotational force mechanism that enables insects with an offset of the pitch axis relative to the wing's chordwise symmetry axis to generate rotational forces in the absence of forward wing motion. Because flying animals produce control actions frequently near stroke reversal, this pitch-axis-offset dependent aerodynamic mechanism may be particularly important for understanding control and manoeuvrability in natural flyers.

scholarly journals The biophysics of bird flight: functional relationships integrate aerodynamics, morphology, kinematics, muscles, and sensors

2015 ◽  
Vol 93 (12) ◽  
pp. 961-975 ◽  
Author(s):  
Douglas L. Altshuler ◽  
Joseph W. Bahlman ◽  
Roslyn Dakin ◽  
Andrea H. Gaede ◽  
Benjamin Goller ◽  
...  
Keyword(s):  
Flight Control ◽  
Sensory Information ◽  
Polar Regions ◽  
Bird Flight ◽  
Avian Flight ◽  
Functional Relationships ◽  
Wing Motion ◽  
Extant Species ◽  
Terrestrial Habitats ◽  
High Elevations

Bird flight is a remarkable adaptation that has allowed the approximately 10 000 extant species to colonize all terrestrial habitats on earth including high elevations, polar regions, distant islands, arid deserts, and many others. Birds exhibit numerous physiological and biomechanical adaptations for flight. Although bird flight is often studied at the level of aerodynamics, morphology, wingbeat kinematics, muscle activity, or sensory guidance independently, in reality these systems are naturally integrated. There has been an abundance of new studies in these mechanistic aspects of avian biology but comparatively less recent work on the physiological ecology of avian flight. Here we review research at the interface of the systems used in flight control and discuss several common themes. Modulation of aerodynamic forces to respond to different challenges is driven by three primary mechanisms: wing velocity about the shoulder, shape within the wing, and angle of attack. For birds that flap, the distinction between velocity and shape modulation synthesizes diverse studies in morphology, wing motion, and motor control. Recently developed tools for studying bird flight are influencing multiple areas of investigation, and in particular the role of sensory systems in flight control. How sensory information is transformed into motor commands in the avian brain remains, however, a largely unexplored frontier.

scholarly journals High Speed Microactuators for Low Aspect Ratio High Speed Micro Aircraft Surfaces

Actuators ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 265
Author(s):  
Ronald Barrett-Gonzalez ◽  
Nathan Wolf
Keyword(s):  
Aspect Ratio ◽  
Flight Control ◽  
High Speed ◽  
High Performance ◽  
Dynamic Range ◽  
Feedback System ◽  
Analytical Models ◽  
Control Surface ◽  
Operational Environment ◽  
Low Aspect Ratio

This paper covers a class of actuators for modern high speed, high performance subscale aircraft. The paper starts with an explanation of the challenges faced by micro aircraft, including low power, extremely tight volume constraints, and high actuator bandwidth requirements. A survey of suitable actuators and actuator materials demonstrates that several classes of piezoceramic actuators are ideally matched to the operational environment. While conventional, linear actuation of piezoelectric actuators can achieve some results, dramatic improvements via reverse-biased spring mechanisms can boost performance and actuator envelopes by nearly an order of magnitude. Among the highest performance, low weight configurations are post-buckled precompressed (PBP) actuator arrangements. Analytical models display large deflections at bandwidths compatible with micro aircraft flight control speed requirements. Bench testing of an example PBP micro actuator powered low aspect ratio flight control surface displays +/−11° deflections through 40 Hz, with no occupation of volume within the aircraft fuselage and good correlation between theory and experiment. A wind tunnel model of an example high speed micro aircraft was fabricated along with low aspect ratio PBP flight control surfaces, demonstrating stable deflection characteristics with increasing speed and actuator bandwidths so high that all major aeromechanical modes could be easily controlled. A new way to control such a PBP stabilator with a Limit Dynamic Driver is found to greatly expand the dynamic range of the stabilator, boosting the dynamic response of the stabilator by more than a factor of four with position feedback system engaged.

scholarly journals The effect of optic flow cues on honeybee flight control in wind

2021 ◽  
Vol 288 (1943) ◽  
pp. 20203051
Author(s):  
Emily Baird ◽  
Norbert Boeddeker ◽  
Mandyam V. Srinivasan
Keyword(s):  
Flight Control ◽  
Optic Flow ◽  
Visual Motion ◽  
Transverse Component ◽  
Natural Environments ◽  
Ground Speed ◽  
Simple Strategy ◽  
Longitudinal Optic ◽  
Transverse Optic ◽  
Robust Systems

To minimize the risk of colliding with the ground or other obstacles, flying animals need to control both their ground speed and ground height. This task is particularly challenging in wind, where head winds require an animal to increase its airspeed to maintain a constant ground speed and tail winds may generate negative airspeeds, rendering flight more difficult to control. In this study, we investigate how head and tail winds affect flight control in the honeybee Apis mellifera , which is known to rely on the pattern of visual motion generated across the eye—known as optic flow—to maintain constant ground speeds and heights. We find that, when provided with both longitudinal and transverse optic flow cues (in or perpendicular to the direction of flight, respectively), honeybees maintain a constant ground speed but fly lower in head winds and higher in tail winds, a response that is also observed when longitudinal optic flow cues are minimized. When the transverse component of optic flow is minimized, or when all optic flow cues are minimized, the effect of wind on ground height is abolished. We propose that the regular sidewards oscillations that the bees make as they fly may be used to extract information about the distance to the ground, independently of the longitudinal optic flow that they use for ground speed control. This computationally simple strategy could have potential uses in the development of lightweight and robust systems for guiding autonomous flying vehicles in natural environments.

Motion Mechanisms in Macaque MT

2005 ◽  
Vol 93 (5) ◽  
pp. 2908-2921 ◽  
Author(s):  
Bart Krekelberg ◽  
Thomas D. Albright
Keyword(s):  
Visual Motion ◽  
Dynamic Range ◽  
Gain Control ◽  
Competitive Interaction ◽  
Energy Model ◽  
Temporal Area ◽  
Motion Patterns ◽  
Mt Neurons ◽  
Motion Energy ◽  
Energy Components

The macaque middle temporal area (MT) is exquisitely sensitive to visual motion and there is a large amount of evidence that neural activity in MT is tightly correlated with the perception of motion. The mechanisms by which MT neurons achieve their directional selectivity, however, have received considerably less attention. We investigated the motion–energy model as a description of motion mechanisms in macaque MT. We first confirmed one of the predictions of the motion–energy model; macaques—just like humans—perceive a reversed direction of motion when a stimulus reverses contrast with every displacement (reverse-phi). This reversal of perceived direction had a clear correlate in the neural responses of MT cells, which were predictive of the monkey's behavioral decisions. Second, we investigated how multiple motion–energy components are combined. Psychophysical data have been used to argue that motion–energy components representing opposite directions are subtracted from each other. Our data show, however, that the interactions among motion–energy components are more complex. In particular, we found that the influence of a given component on the response to a stimulus consisting of multiple components depends on factors other than the response to that component alone. This suggests that there are subthreshold nonlinear interactions among multiple motion–energy components; these could take place within MT or in earlier stages of the motion network such as V1. We propose a model that captures the complexity of these component interactions by means of a competitive interaction among the components. This provides a better description of the MT responses than the subtractive motion opponency envisaged in the motion–energy model, even when the latter is combined with a gain-control mechanism. The competitive interaction extends the dynamic range of the cells and allows them to provide information on more subtle changes in motion patterns, including changes that are not purely directional.

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