Avoiding topsy-turvy: how Anna's hummingbirds (<i>Calypte anna</i>) fly through upward gusts

Badger, Marc; Wang, Hao; Dudley, Robert

doi:10.1242/jeb.176263

Cited by 16 publications

(13 citation statements)

References 36 publications

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“…For example, as a hiker navigates rough terrain, each step requires adjustments of foot placement, stance duration, and force generation to maintain stability and to progress. As a hummingbird encounters a gust of wind, it makes rapid corrections to recover stable flight (Badger et al, 2019). Food oral processing involves instantto-instant decision making about chewing, bolus molding, and transport for swallowing that depend on the changing mechanical properties of food (Chen, 2009).…”

Section: Introductionmentioning

confidence: 99%

Rapid Adaptation to Changing Mechanical Load by Ordered Recruitment of Identified Motor Neurons

Gill

Chiel

2020

eNeuro

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As they interact with their environment and encounter challenges, animals adjust their behavior on a moment-to-moment basis to maintain task fitness. This dynamic process of adaptive motor control occurs in the nervous system, but an understanding of the body's biomechanics is essential to properly interpret the behavioral outcomes. To study how animals respond to changing task conditions, we used a model system in which the functional roles of identified neurons and the relevant biomechanics are well understood and can be studied in intact behaving animals: feeding in the marine mollusc Aplysia. We monitored the motor neuronal output of the feeding circuitry as intact animals fed on uniform food stimuli under unloaded and loaded conditions, and we measured the force of retraction during loaded swallows. We observed a previously undescribed pattern of force generation, which can be explained within the appropriate biomechanical context by the activity of just a few key, identified motor neurons. We show that, when encountering load, animals recruit identified retractor muscle motor neurons for longer and at higher frequency to increase retraction force duration. Our results identify a mode by which animals robustly adjust behavior to their environment which is experimentally tractable to further mechanistic investigation. Significance Statement Understanding adaptive motor control requires studying the brain and body together during behavior. Studying motor control systems at the level of individual neurons in intact animals is challenging. The Aplysia feeding system has individual neurons that can be identified from animal to animal and well-studied biomechanics. Prior work showed that animals respond adaptively to changing mechanical load, but did not measure or did not find strong neural correlates. As animals generate increasing force on food, we find that the increased activity and size-ordered recruitment of identified motor neurons allows animals to adapt their behavior. This is the first demonstration of a relationship between identified motor neurons and adaptive motor behavior in intact behaving Aplysia in response to changing mechanical load.

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Section: Introductionmentioning

confidence: 99%

Rapid Adaptation to Changing Mechanical Load by Ordered Recruitment of Identified Motor Neurons

Gill

Chiel

2020

eNeuro

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“…Birds may cope with gusts in a similar way, but the response times and dynamics by which they deal with aerodynamic perturbations are not known, as simultaneous measurements of both the bird's kinematics and the properties of the unsteady airflows they encounter are required. Most previous studies of bird flight mechanics (but see [8]) have taken place in steady laboratory conditions, such as corridors [9][10][11], or wind tunnels [12][13][14][15][16][17], or outdoors [18][19][20][21], where the moment-to-moment variation in the wind that the birds encountered could not be quantified.…”

Section: Introductionmentioning

confidence: 99%

Bird wings act as a suspension system that rejects gusts

et al. 2020

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Musculoskeletal systems cope with many environmental perturbations without neurological control. These passive preflex responses aid animals to move swiftly through complex terrain. Whether preflexes play a substantial role in animal flight is uncertain. We investigated how birds cope with gusty environments and found that their wings can act as a suspension system, reducing the effects of vertical gusts by elevating rapidly about the shoulder. This preflex mechanism rejected the gust impulse through inertial effects, diminishing the predicted impulse to the torso and head by 32% over the first 80 ms, before aerodynamic mechanisms took effect. For each wing, the centre of aerodynamic loading aligns with the centre of percussion, consistent with enhancing passive inertial gust rejection. The reduced motion of the torso in demanding conditions simplifies crucial tasks, such as landing, prey capture and visual tracking. Implementing a similar preflex mechanism in future small-scale aircraft will help to mitigate the effects of gusts and turbulence without added computational burden.

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“…[27][28][29][30][31][32][33] Nakata et al 34 showed that flexible flapping wings can be beneficial for longitudinal gust mitigation. Badger et al 35 found that the use of a deflectable tail on a glider model can enhance the stability of Anna's hummingbirds flying into a vertical gust. Jakobi et al 36 studied the effects of gusts impinging from different directions on bumblebees and found that bees can mitigate the gust influence by using different maneuvering strategies.…”

Section: Introductionmentioning

confidence: 99%