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"Locomotion."
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Control of limb loading during active horizontal perturbations at moderate and fast trots in rats
To understand how small animals cope with complex, unstructured, and unpredictable substrates, we analysed the kinetics of female rats (
) moving at a fast and at a moderate trot over an unperturbed substrate and a substrate subjected to active horizontal perturbations. Perturbations were active single forwards or backwards displacements of an instrumented platform by 5 mm or 10 mm amplitudes in 0.05 s. Single leg ground reaction forces (SLGRF) were collected for unperturbed and perturbed locomotion (hindlimbs: 50/102, forelimbs: 45/130, respectively). When negotiating horizontal perturbations, rats displayed gait resetting (braking, accelerating) and non-resetting behaviours. Feedforward strategies differed between the fore- and hindlimbs. In circa 60% of the perturbed trials, forelimbs started the step in acceleration mode, while hindlimbs began the stance mostly in non-resetting mode (
45%). In about 50% of all perturbed steps, the impulse provided by the SLGRF displayed a change in behaviour according to the expected response to the perturbation. The remaining 50% retained the feedforward strategy. Still, most perturbed trials displayed changes in SLGRF patterns that indicated passive and active reactions to platform shifts. Our results indicate that rats’ sensorimotor control system tunes fore- and hindlimbs differently in expectation of a perturbation. In addition, the tendon-muscle systems of the limbs are recruited to prevent leg collapse at the beginning and end of the stance. At lower speeds, spinal and/or higher centre commands have enough time to re-adapt limb behaviour. At higher locomotion speeds, rats rely more on their limbs’ intrinsic stability and feedforward control.
Journal Article
Animals on the go
Describes the ways in which animals move, including hopping, slithering, and soaring.
Book
A gut microbial factor modulates locomotor behaviour in Drosophila
While research into the biology of animal behaviour has primarily focused on the central nervous system, cues from peripheral tissues and the environment have been implicated in brain development and function
1
. There is emerging evidence that bidirectional communication between the gut and the brain affects behaviours including anxiety, cognition, nociception and social interaction
1
–
9
. Coordinated locomotor behaviour is critical for the survival and propagation of animals, and is regulated by internal and external sensory inputs
10
,
11
. However, little is known about how the gut microbiome influences host locomotion, or the molecular and cellular mechanisms involved. Here we report that germ-free status or antibiotic treatment results in hyperactive locomotor behaviour in the fruit fly
Drosophila melanogaster
. Increased walking speed and daily activity in the absence of a gut microbiome are rescued by mono-colonization with specific bacteria, including the fly commensal
Lactobacillus brevis
. The bacterial enzyme xylose isomerase from
L. brevis
recapitulates the locomotor effects of microbial colonization by modulating sugar metabolism in flies. Notably, thermogenetic activation of octopaminergic neurons or exogenous administration of octopamine, the invertebrate counterpart of noradrenaline, abrogates the effects of xylose isomerase on
Drosophila
locomotion. These findings reveal a previously unappreciated role for the gut microbiome in modulating locomotion, and identify octopaminergic neurons as mediators of peripheral microbial cues that regulate motor behaviour in animals.
Female
Drosophila
that lack a microbiota are hyperactive, and xylose isomerase from
Lactobacillus brevis
is sufficient to reverse this effect.
Journal Article
Hip-hop dancers
Children will love the comical photographs of animals in different hip-hop dance positions! Dancing lemurs, bunnies, chimpanzees, and elephants groove to a simple rhyme pattern in this entertaining book. Children are asked to choose the hip-hop animal they think is the best dancer, as well as the animal or group of animals having the most fun.
Book
Locomotion dynamics of hunting in wild cheetahs
Although the cheetah is recognised as the fastest land animal, little is known about other aspects of its notable athleticism, particularly when hunting in the wild. Here we describe and use a new tracking collar of our own design, containing a combination of Global Positioning System (GPS) and inertial measurement units, to capture the locomotor dynamics and outcome of 367 predominantly hunting runs of five wild cheetahs in Botswana. A remarkable top speed of 25.9 m s
−1
(58 m.p.h. or 93 km h
−1
) was recorded, but most cheetah hunts involved only moderate speeds. We recorded some of the highest measured values for lateral and forward acceleration, deceleration and body-mass-specific power for any terrestrial mammal. To our knowledge, this is the first detailed locomotor information on the hunting dynamics of a large cursorial predator in its natural habitat.
A novel tracking collar provides highly precise location, speed and acceleration data from 367 runs by five cheetahs in the wild; although a top speed of 58 m.p.h. was reported, few runs were above 45 m.p.h. with the average run around 31 m.p.h., and hunting success depended on grip, manoeuvrability and muscle power rather than outright speed.
The hunting prowess of the cheetah
The cheetah is widely recognized as the fastest animal on land, with a reported top speed of 29 metres per second. However, few precise measurements have been made and only rarely have speeds faster than racing greyhounds (18 m s
−1
) been recorded. Now a team from the Royal Veterinary College, UK, working with the Botswana Predator Conservation Trust, has used custom-built tracking collars containing GPS and inertial measurement units to capture the locomotor dynamics of cheetahs hunting in the wild. The top speed observed was 25.9 m s
−1
(93 kilometres per hour). Most hunts involved only moderate speeds, their success relying on a combination of power, acceleration and agility.
Journal Article
Convergence of undulatory swimming kinematics across a diversity of fishes
Fishes exhibit an astounding diversity of locomotor behaviors from classic swimming with their body and fins to jumping, flying, walking, and burrowing. Fishes that use their body and caudal fin (BCF) during undulatory swimming have been traditionally divided into modes based on the length of the propulsive body wave and the ratio of head:tail oscillation amplitude: anguilliform, subcarangiform, carangiform, and thunniform. This classification was first proposed based on key morphological traits, such as body stiffness and elongation, to group fishes based on their expected swimming mechanics. Here, we present a comparative study of 44 diverse species quantifying the kinematics and morphology of BCF-swimming fishes. Our results reveal that most species we studied share similar oscillation amplitude during steady locomotion that can be modeled using a second-degree order polynomial. The length of the propulsive body wave was shorter for species classified as anguilliform and longer for those classified as thunniform, although substantial variability existed both within and among species. Moreover, there was no decrease in head:tail amplitude from the anguilliform to thunniform mode of locomotion as we expected from the traditional classification. While the expected swimming modes correlated with morphological traits, they did not accurately represent the kinematics of BCF locomotion. These results indicate that even fish species differing as substantially in morphology as tuna and eel exhibit statistically similar two-dimensional midline kinematics and point toward unifying locomotor hydrodynamic mechanisms that can serve as the basis for understanding aquatic locomotion and controlling biomimetic aquatic robots.
Journal Article
Flying frogs and walking fish : leaping lemurs, tumbling toads, jet-propelled jellyfish, and more surprising ways that animals move
\"Explore unusual animal locomotion through incredible art and fascinating facts from the Caldecott Honor-winning team Steve Jenkins and Robin Page\"-- Provided by publisher.
Book
Dual-mode operation of neuronal networks involved in left–right alternation
A group of transcriptionally defined spinal neurons, V0 neurons, are identified as necessary for the control of normal alternation of left and right limbs in mice.
Locomotion step change derives from V0 neurons
Locomotion involves coordinated and sequential activation of neurons and muscles on both sides of the body. Ole Kiehn and colleagues identify a group of transcriptionally defined spinal neurons, the V0 neurons derived from the p0 progenitor domain of the ventral spinal chord, as being responsible for controlling alternation of left and right limbs in mouse. Both excitatory and inhibitory V0 neurons exist, and ablation of individual populations selectively impairs alternation at different locomotion speeds.
All forms of locomotion are repetitive motor activities that require coordinated bilateral activation of muscles. The executive elements of locomotor control are networks of spinal neurons that determine gait pattern through the sequential activation of motor-neuron pools on either side of the body axis
1
,
2
,
3
,
4
. However, little is known about the constraints that link left–right coordination to locomotor speed. Recent advances have indicated that both excitatory and inhibitory commissural neurons may be involved in left–right coordination
5
,
6
,
7
. But the neural underpinnings of this, and a possible causal link between these different groups of commissural neurons and left–right alternation, are lacking. Here we show, using intersectional mouse genetics, that ablation of a group of transcriptionally defined commissural neurons—the V0 population—leads to a quadrupedal hopping at all frequencies of locomotion. The selective ablation of inhibitory V0 neurons leads to a lack of left–right pattern at low frequencies, mixed coordination at medium frequencies, and alternation at high locomotor frequencies. When ablation is targeted to excitatory V0 neurons, left–right alternation is present at low frequencies, and hopping is restricted to medium and high locomotor frequencies. Therefore, the intrinsic logic of the central control of locomotion incorporates a modular organization, with two subgroups of V0 neurons required for the existence of left–right alternating modes at different speeds of locomotion. The two molecularly distinct sets of commissural neurons may constrain species-related naturally occurring frequency-dependent coordination and be involved in the evolution of different gaits.
Journal Article