Locomotion

The sinus tarsi syndrome is now a well-defined entity of foot pathology. Usually post-traumatic, it is characterised by pain over the lateral opening of the sinus tarsi and a feeling of instability of the ankle. We were able to define two objective criteria for the syndrome: arthrography of the subtalar joint shows specific abnormalities and recording of the electromyographic function of the peronei demonstrates abnormalities during walking. Conservative treatment is successful in about two-thirds of the cases. In other cases a simple surgical procedure can cure or improve 90% of the patients. Le syndrome du sinus du tarse est une entité bien définie de la pathologie du pied. Le plus souvent post-traumatique, il se caractérise par une douleur à l'orifice externe du sinus du tarse et une instabilité de l'arrière-pied. Nous avons pu définir deux symptômes objectifs de ce syndrome parfois difficile à diagnostiquer: l'arthrographie de l'articulation sous-astragalienn...

The etiology of Periodic Limb Movement Disorder (PLMD) as well as the precise role of melatonin in human physiology remains poorly understood. Inspired by a single case observation we performed the presented study in order to obtain first evidence for the hypothesis that exogenous melatonin would decrease PLM's and thereby improves symptoms of PLMD patients. N/A. N/A. Nine patients with first time diagnosis of PLMD without RLS were treated over a six-week period with 3 mg melatonin, taken between 10 and 11 p.m. N/A. Melatonin improved well-being in 7 of the 9 patients. Polysomnography, performed prior and at the end of melatonin treatment, demonstrated a significant reduction of investigated movement parameters, such as PLMs, PLM index, PLMs with arousals and PLM-arousal index. Actigraphy, measured over 14 nights prior and during the last 14 days of melatonin treatment, showed a significant reduction in movement rate and minutes with movements during Time in Bed. The temporal di...

Magnetotactic bacteria (MTB) are distributed ubiquitously in sediments from coastal environments to the deep sea. The Pacific Manganese Nodule Province contains numerous polymetallic nodules mainly composed of manganese, iron, cobalt, copper and nickel. In the present study we used Illumina MiSeq sequencing technology to assess the communities of putative MTB in deep sea surface sediments at nine stations in the east Pacific Manganese Nodule Province. A total of 402 sequence reads from MTB were classified into six OTUs. Among these, OTU113 and OTU759 were affiliated with the genus Magnetospira, OTU2224 and OTU2794 were affiliated with the genus Magnetococcus and Magnetovibrio, respectively, OTU3017 had no known genus affiliation, and OTU2556 was most similar to Candidatus Magnetananas. Interestingly, OTU759 was widely distributed, occurring at all study sites. Magnetism measurements revealed that all sediments were dominated by low coercivity, non-interacting single domain magnetic ...

We present a nonlinear dynamical model of the human gait control system in a variety of gait regimes. The stride-interval time series in normal human gait is characterized by slightly multifractal fluctuations. The fractal nature of the fluctuations becomes more pronounced under both an increase and decrease in the average gait. Moreover, the long-range memory in these fluctuations is lost when the gait is keyed on a metronome. Human locomotion is controlled by a network of neurons capable of producing a correlated syncopated output. The central nervous system is coupled to the motocontrol system, and together they control the locomotion of the gait cycle itself. The metronomic gait is simulated by a forced nonlinear oscillator with a periodic external force associated with the conscious act of walking in a particular way.

Many organisms spanning from bacteria to mammals orient to the earth's magnetic field. For a few animals, central neurons responsive to earth-strength magnetic fields have been identified; however, magnetosensory neurons have yet to be identified in any animal. We show that the nematode Caenorhabditis elegans orients to the earth's magnetic field during vertical burrowing migrations. Well-fed worms migrated up, while starved worms migrated down. Populations isolated from around the world, migrated at angles to the magnetic vector that would optimize vertical translation in their native soil, with northern- and southern-hemisphere worms displaying opposite migratory preferences. Magnetic orientation and vertical migrations required the TAX-4 cyclic nucleotide-gated ion channel in the AFD sensory neuron pair. Calcium imaging showed that these neurons respond to magnetic fields even without synaptic input. C. elegans may have adapted magnetic orientation to simplify their verti...

The sinus tarsi syndrome is now a well-defined entity of foot pathology. Usually post-traumatic, it is characterised by pain over the lateral opening of the sinus tarsi and a feeling of instability of the ankle. We were able to define two objective criteria for the syndrome: arthrography of the subtalar joint shows specific abnormalities and recording of the electromyographic function of the peronei demonstrates abnormalities during walking. Conservative treatment is successful in about two-thirds of the cases. In other cases a simple surgical procedure can cure or improve 90% of the patients. Le syndrome du sinus du tarse est une entité bien définie de la pathologie du pied. Le plus souvent post-traumatique, il se caractérise par une douleur à l'orifice externe du sinus du tarse et une instabilité de l'arrière-pied. Nous avons pu définir deux symptômes objectifs de ce syndrome parfois difficile à diagnostiquer: l'arthrographie de l'articulation sous-astragalienne révèle des anomalies spécifiques dans tous les cas et l'enregistrement de la fonction automatique des péroniers durant la marche montre également des modifications claires de cette activité. Le traitement conservateur est suffisant dans environ 2/3 des cas. Chez les autres, une intervention chirurgicale simple guérit ou améliore notablement 90% des patients.

Until now, there has been neither an agreed-upon experimental model nor descriptors of the clinical symptoms that occur over the course of acute murine infection. The aim of this work is to use non-invasive methods to evaluate clinical signs in Swiss Webster mice that were experimentally infected with the Y strain of Trypanosoma cruzi during acute phase (Inf group). Infected mice showed evident clinical changes beginning in the second week of infection (wpi): (i) animals in hunched postures, closed eyes, lowered ears, peeling skin, increased piloerection, prostration and social isolation; (ii) significant decrease in the body weight (Inf: 26.2±2.6 g vs. non-infected group (NI) 34.2±2.5 g), chow (1.5±0.3 vs. 6.3±0.5 mg) and water (2.4±0.5 vs. 5.8±0.7 ml) intake; (iii) significant decrease of the spontaneous activity as locomotor parameters: distance (0.64±0.06 vs. 1.8±0.13 m), the velocity (1.9±0.3 vs. 6.7±1.5 cm/s) and exploratory behaviour by the frequency (1.0±0.5 vs.5....

Flying fishes are extraordinary aquatic vertebrates capable of gliding great distances over water by exploiting their enlarged pectoral fins and asymmetrical caudal fin. Some 50 species of extant flying fishes are classified in the Exocoetidae (Neopterygii: Teleostei), which have a fossil record no older than the Eocene. The Thoracopteridae is the only pre-Cenozoic group of non-teleosts that shows an array of features associated with the capability of over-water gliding. Until recently, however, the fossil record of the Thoracopteridae has been limited to the Upper Triassic of Austria and Italy. Here, we report the discovery of exceptionally well-preserved fossils of a new thoracopterid flying fish from the Middle Triassic of China, which represents the earliest evidence of an over-water gliding strategy in vertebrates. The results of a phylogenetic analysis resolve the Thoracopteridae as a stem-group of the Neopterygii that is more crown-ward than the Peltopleuriformes, yet more ba...

Changes in stride frequency and length with speed are key parameters in animal locomotion research. They are commonly measured in a laboratory on a treadmill or by filming trained captive animals. Here, we show that a clustering approach can be used to extract these variables from data collected by a tracking collar containing a GPS module and tri-axis accelerometers and gyroscopes. The method enables stride parameters to be measured during free-ranging locomotion in natural habitats. As it does not require labelled data, it is particularly suitable for use with difficult to observe animals. The method was tested on large data sets collected from collars on free-ranging lions and African wild dogs and validated using a domestic dog.

Grid cells in the medial entorhinal cortex (MEC) are part of an environment-independent spatial coordinate system. To determine how information about location, direction, and distance is integrated in the grid-cell network, we recorded from each principal cell layer of MEC in rats that ...

Abslract-A mathematical model for terrestrial running is presented, based on a leg with the properties of a simple spring. Experimental force-platform evidence is reviewed justifying the formulation of the model. The gov$ming differential equations are given in dimensionless form lo make the results representative of animals bfall body sizes. The dimensionless input parameters are: f./, a horizontal Froude number based on forward speed and leg length; I'. a vertical Froude number based on vertical landing velocity and leg length, and KLeP, a dimensionless stiffness for the leg-spring. Results show that at high forward speed, K,,, is a nearly liiear function of both U and V, while the eflective vertical stitTness is a quadratic function of U. For each U. V pair. the simulation shows that the vertical force al mid-step may be minimized by the choice of a particuldr step length. A particularly useful specification of the theory occurs when both KLEo and t' are assumed~fined. When K,,o= IS and Y=O.18. Ihe model makes predictions of relative stride length S and initial leg angle 8, (hat are in good agreement with experimental data obtained from the literature. NOhlENCLATl'RF: Dimcwsional sarichles 21, sin 0, 1. 1, "-v X Y maximum vertical force horizlontal force on mass vertical foxy on mass spring stiffness of leg cl%xlivc vertical stilTncss (same as k,,, in Ihc cast of vertical hopping; otherwise dikrcnt) instantaneous length of leg [Fig. 2(h) J starling and ending leg length body mass stride length, distance between footprints of same fool step kngth. distance moved during one contact period time in air time of contact horizontal velocity at beginning of contact vertiaal velocity at beginning of contact horizbntal coordinate of body mass [Fig. 2(b)] verridal coordinate of body mass [Figs 2(a) and I'31 Dimensionless variables dimensionless vertical acceleraGon dimensionless leg sriflncss dimensionless vertical sMness dimensionless leg length relative stride length horizontal Froude number vertical Froude number Groucho number lSTROOUCTlON This paper presents a simple yet comprehensive theory for runhing in terrestrial animals. We first review experimental evidence justifying our main assumption , that the leg is a spring. Then we give a series of results predicting important parameters such as the peak ground reaction force and the stride length. Finally. we compare these predictions with published experiments. We seek the simplest model of running capable of explaining how the stiffness of the leg spring couples with speed. Before beginning. however. it is useful to ask an even more basic question: what distinguishes walking and running? At lirst glance, the diffcrencc bctwccn walking and running in terrestrial animals would appear obvious. In running, all feet are in the air at some point in the gait cycle, whereas in walking there is always at least one foot on the ground. This distinction is appropriate most of the time for most animals, but thcrc are times when it fails. When humans run along a circular path, the aerial phase of the motion disappears if the turn has a sufficiently small radius (Greene and McMahon, 1979a). When humans run on a treadmill at constant speed but deliberately bend their knees more than usual in order to decrease the vertical stiffness of the legs and body, again the aerial phase is found to disappear when the extra knee Aexion is great enough (McMahon et al., 1987). A better criterion for distinguishing between walking and running is the one put forward by Cavagna et nl. (1976). On the basis of observations in humans, they pointed out that in walking, the center of mass is highest in mid-step, when the hip of the stance leg passes over the ankle. In running, by comparison, the center of mass is lowest at mid-step. Thus in walking, but not in running, gravitational potential energy is stored in the lirst half of the walking step as the center of mass rises, and returned in the form of kinetic energy during the second half of the step as the center of mass falls. Cavagna et ol. (1976) emphasized that in running, changes of forward kinetic energy and gravitational potential energy are in phase and therefore cannot exchange with one another to smooth out fluctuations 65