Vertical Locomotion Research Articles

Vertical locomotion improves horizontal locomotion: effects of climbing on gait and other mobility aspects in Parkinson’s disease. A secondary analysis from a randomized controlled trial

BackgroundIn the Climb Up! Head Up! trial, we showed that sport climbing reduces bradykinesia, tremor, and rigidity in mildly to moderately affected participants with Parkinson’s disease. This secondary analysis aimed to evaluate the effects of sport climbing on gait and functional mobility in this cohort.MethodsClimb Up! Head Up! was a 1:1 randomized controlled trial. Forty-eight PD participants (Hoehn and Yahr stage 2–3) either participated in a 12-week, 90-min-per-week sport climbing course (intervention group) or were engaged in regular unsupervised physical activity (control group). Relevant outcome measures for this analysis were extracted from six inertial measurement units placed on the extremities, chest, and lower back, that were worn during supervised gait and functional mobility assessments before and after the intervention. Assessments included normal and fast walking, dual-tasking walking, Timed Up and Go test, Instrumented Stand and Walk test, and Five Times Sit to Stand test.ResultsCompared to baseline, climbing improved gait speed during normal walking by 0.09 m/s (p = 0.005) and during fast walking by 0.1 m/s. Climbing also reduced the time spent in the stance phase during fast walking by 0.03 s. Climbing improved the walking speed in the 7-m- Timed Up and Go test by 0.1 m/s (p < 0.001) and the turning speed by 0.39 s (p = 0.052), the speed in the Instrumented Stand and Walk test by 0.1 m/s (p < 0.001), and the speed in the Five Times Sit to Stand test by 2.5 s (p = 0.014). There was no effect of sport climbing on gait speed or gait variables during dual-task walking.ConclusionsSport climbing improves gait speed during normal and fast walking, as well as functional mobility in people with Parkinson’s disease.Trial registration This study was registered within the U.S. National Library of Medicine (No: NCT04569981, date of registration September 30th, 2020)

Lasting mesothalamic dopamine imbalance and altered exploratory behavior in rats after a mild neonatal hypoxic event.

Adversities during the perinatal period can decrease oxygen supply to the fetal brain, leading to various hypoxic brain injuries, which can compromise the regularity of brain development in different aspects. To examine the catecholaminergic contribution to the link between an early-life hypoxic insult and adolescent behavioral aberrations, we used a previously established rat model of perinatal hypoxia but altered the hypobaric to normobaric conditions. Exploratory and social behavior and learning abilities were tested in 70 rats of both sexes at adolescent age. Inherent vertical locomotion, sensory-motor functions and spatial learning abilities were explored in a subset of animals to clarify the background of altered exploratory behavior. Finally, the concentrations of dopamine (DA) and noradrenaline in midbrain and pons, and the relative expression of genes for DA receptors D1 and D2, and their down-stream targets (DA- and cAMP-regulated phosphoprotein, Mr 32 kDa, the regulatory subunit of protein kinase A, and inhibitor-5 of protein phosphatase 1) in the hippocampus and thalamus were investigated in 31 rats. A lesser extent of alterations in exploratory and cognitive aspects of behavior in the present study suggests that normobaric conditions mitigate the hypoxic injury compared to the one obtained under hypobaric conditions. Increased exploratory rearing was the most prominent consequence, with impaired spatial learning in the background. In affected rats, increased midbrain/pons DA content, as well as mRNA levels for DA receptors and their down-stream elements in the thalamus, but not the hippocampus, were found. We can conclude that a mild hypoxic event induced long-lasting disbalances in mesothalamic DA signaling, contributing to the observed behavioral alterations. The thalamus was thereby indicated as another structure, besides the well-established striatum, involved in mediating hypoxic effects on behavior through DA signaling.

Keel bone fractures affect laying hens' mobility, but no evidence for reciprocal effects.

Keel bone fractures (KBF) are prevalent in commercial laying hens and are considered one of the greatest welfare concerns in the egg-production industry. While clear associations exist between KBF and animal mobility, suggesting that KBF impair mobility, the effect of mobility on KBF remains unclear. We combined data from three studies that assessed keel bone fracture severity through radiographs and monitored hens' transitions between different zones of a multi-tier aviary system (the three tiers, a littered floor, and a winter garden) the week prior to radiograph. For each hen, we extracted two daily movement behaviours: the vertical distance travelled and the mean number of zones crossed within one transition; and two daily space-use behaviours: the time spent in the top tier and the unevenness of time spent across zones. We used hierarchical Bayesian continuous time dynamic modelling to estimate how a change in a behaviour predicted a later change in keel bone fracture severity, and vice versa. Increased fracture severity did not predict later changes in space-use behaviours, but it did predict changes in movement behaviours. Specifically, increased fracture severity led to decreased vertical travelled distance and a tendency to cross more zones within one transition, suggesting impaired mobility in hens with increased fracture severity. In contrast, we found no evidence that movement or space-use behaviours predict later change in fracture severity, challenging previous literature suggesting that vertical locomotion through jumping and flying may exacerbate keel bone fractures in complex three-dimensional systems due to increased risk of collisions. However, similar efforts accounting for the location of fractures on the keel could unveil the potential influence of movement and space-use behaviours in the formation and change (healing or worsening) of KBF and increase our ability to mitigate their effects.

Spontaneous remyelination following dimethyl sulfoxide-induced demyelination is accompanied by behavioral and neurological alteration in mice

Introduction: Dimethyl sulfoxide (DMSO) is a commonly used solvent that can be applied in experimental studies for preparation of hydrophobic solutions as well as in capacity of a cryopreservative in transplantology. According to modern data acquired from in vitro experiments, DMSO is able to change the structure of myelin by decreasing synthesis of its main components and inhibiting oligodendrocyte genesis. Aim of the study: We studied influence of DMSO on anxiety and compulsive-like behavior, pain perception, motor coordination and myelin quantity in the corpus callosum of the C57BL/6 mice brain after prolonged oral administration of the solvent and 4 weeks after administration was stopped. Materials and Methods: All the experiments were conducted on male inbreed C57BL/6 mice. DMSO was added to drinking water to achieve 0.01% concentration, and the obtained solution was administered ad libitum for 6 weeks. After 6 weeks of administration of DMSO and 4 weeks after administration of DMSO was stopped, anxiety-like behavior in open field test, compulsive-like behavior in marble burying test, motor coordination in rotarod test, pain perception in tail-immersion test, as well as myelin quantity in the corpus callosum were evaluated. Results: It was established that DMSO consumed for 6 weeks was associated with decrease in the myelin quantity in thecorpus callosum and thermal hyperalgesia in tail-immersion test. During 4-week period after DMSO administration was stopped, attenuation of demyelination was observed, followed by an increase in thermal hyperalgesia in tail-immersion test, as well as vertical locomotion and exploratory activity in open field test. Conclusions: 6-week ad libitum administration of 0.01% DMSO solution was associated with demyelination in corpus callosum of С57BL/6 mice, followed by thermal hyperalgesia. Cessation of DMSO led to spontaneous remyelination with an increase in thermal hyperalgesia, vertical locomotion and exploratory activity of mice.

The effects of chronic unpredicted mild stress on maternal negative emotions and gut microbiota and metabolites in pregnant rats.

Chronic long-term stress is associated with a range of disorders, including depression and a variety of other chronic illnesses. It is well known that maternal exposure to psychosocial stress during pregnancy significantly increases the likelihood of adverse pregnancy outcomes. The gut microbiota has been a popular topic, it is a key mediator of the gut-brain axis and plays an important role in human health; changes in the gut microbiota have been related to chronic stress-induced health impairment, however, the relationship between maternal negative emotions and abnormal gut microbiota and its metabolites during maternal exposure to chronic stress during pregnancy remains unclear. Pregnant rats were subjected to chronic unpredicted mild stress (CUMS) to establish the rat model of chronic stress during pregnancy. The behavioral changes were recorded using sucrose preference test (SPT) and open-field test (OFT), plasma corticosterone levels were determined by radioimmunoassay, and a comprehensive method combining 16S rRNA gene sequencing and gas chromatography-mass spectrometry (GC-MS) metabolomics was used to study the effects of stress during pregnancy on the function of intestinal microbiota and its metabolites. Chronic stress during pregnancy not only increased maternal plasma corticosterone (P < 0.05), but also caused maternal depression-like behaviors (P < 0.05). Chronic stress during pregnancy changed the species composition at the family level of maternal gut microbiota, the species abundance of Ruminococcaceae in the stress group (23.45%) was lower than the control group (32.67%) and the species abundance of Prevotellaceae in the stress group (10.45%) was higher than the control group (0.03%) (P < 0.05). Vertical locomotion and 1% sucrose preference percentage in pregnant rats were negatively correlated with Prevotellaceae (r=-0.90, P<0.05). Principal component analysis with partial least squares discriminant analysis showed that the integration points of metabolic components in the stress and control groups were completely separated, indicating that there were significant differences in the metabolic patterns of the two groups, and there were seven endogenous metabolites that differed (P < 0.05). The negative emotional behaviors that occur in pregnant rats as a result of prenatal chronic stress may be associated with alterations in the gut microbiota and its metabolites. These findings provide a basis for future targeted metabolomics and gut flora studies on the effects of chronic stress during pregnancy on gut flora.

Behavioral effects of Chaenomeles maulei fruit juice in rats with impaired circadian rhythm

Impaired circadian rhythm (ICR) is a commonly used model of mild stress. The fruit juice of Chaenomeles japonica var. maulei (Mast.) Lavall'e (CMFJ) is rich in polyphenols known for their anti-inflammatory, antioxidant, and neuroprotective properties. The aim of this study was to investigate the effects of CMFJ on the behavior of rats subjected to ICR. Male Wistar rats were divided into five groups of 10 animals each: control group (without ICR), the ICR, ICR+CMFJ2.5, ICR+CMFJ5, and ICR+CMFJ10 groups. ICR was induced by exposing rats to 14 days of constant light. Over these days, oral treatment was administered with distilled water (the control and ICR groups) and CMFJ at doses 2.5, 5, and 10ml/kg for the respective groups. Then we performed the open field test, the social interaction test (SIT), and the forced swim test (FST) to assess rats' locomotion, anxiety, and the depressive-like behavior, respectively. The ICR animals increased their horizontal and vertical locomotion when compared to the controls. The ICR rats did not change significantly the social interaction time in the SIT test and immobility time in the FST. The horizontal and vertical activity of theICR+CMFJ10 rats was reduced in comparison with ICR animals. Compared to ICR rats, the animals treated with CMFJ at doses of 2.5 and 10ml/kg demonstrated an improved social interaction and decreased immobility time in the FST. ]CMFJ prevented the development of ICR-induced hyperactivity and showed an anxiolytic-like and antidepressant-like effect, probably due to its high polyphenol content.

Three toes and three modes: Dynamics of terrestrial, suspensory, and vertical locomotion in brown-throated three-toed sloths (Bradypodidae, Xenarthra).

Living sloths exhibit numerous anatomical specializations towards inverted quadrupedalism, however, previous studies have noted a more varied locomotor repertoire than previously anticipated. In this study, we present spatiotemporal gait characteristics and triaxial kinetic data from the brown-throated three-toed sloth (Bradypus variegatus) across three locomotor modes: terrestrial quadrupedal "crawling", suspensory walking, and vertical climbing. Compared to quadrupedal crawling and suspensory walking, B. variegatus adopted longer contact times and stride durations, larger duty factors, and greater speed during vertical climbing. Net fore-aft impulses were significantly greater during vertical climbing in both limb pairs than in quadrupedal crawling and suspensory walking. Functionally, during quadrupedal crawling and vertical climbing, both limb pairs served propulsive roles, while differentiation between a propulsive forelimb and braking hindlimb was observed during suspension. Net tangential forces differentiated vertical climbing kinetics from the other modes of locomotion, with the introduction of bidirectional pulling and pushing forces in the forelimb and hindlimb, respectively. The net mediolateral impulses were similar in vertical climbing and quadrupedal crawling as both limb pairs directed forces in one direction, whereas during suspensory walking, the laterally dominant forelimb was opposed by the medially dominant hindlimb. In total, this study provides novel data on the diverse locomotor dynamics in a slow-moving arboreal tetrapod and posits new testable hypotheses about the neuroplasticity and ease of transitioning between locomotor behaviors. The strikingly similar kinetic profiles of quadrupedal crawling and suspensory walking compared to vertical climbing suggest shared neuromuscular and mechanical demands between these mirrored locomotor modes.

Factors affecting locomotor activity of search and rescue dogs: The importance of terrain, vegetation and dog certification

Ground SAR work is a demanding activity that requires trained dogs to work reliably for hours in various terrain and environmental conditions. Factors that would affect a dog’s physical performance in conditions imitating a real SAR mission remain poorly studied. We tested a total of 50 shepherd dogs between 2 and 10 years of age. The group comprised dogs that were both certified and uncertified in SAR work. Testing took place during 5 simulated all-day search sessions. We wanted to know how terrain slope, vegetation cover, ambient temperature, and the number of search rounds would affect locomotor activity of both certified and uncertified dogs. The locomotor activity of dogs was described by vertical and horizontal speed, duration of the search as well as the ratio of time spent in vertical (i.e. uphill) locomotion to total time of locomotion (this ratio is herein referred to as “effectiveness”), and duration of the search. We found out that SAR certification was associated with an increased effectiveness; certified dogs spent more time in energy-conserving horizontal locomotion along contour lines. Terrain and environmental factors influenced both certified and uncertified dogs; a slope of 11° or greater increased vertical speed and duration of searching but decreased effectiveness. Thick vegetation slowed horizontal and vertical locomotion, impaired effectiveness and prolonged search times. Relatively high temperatures (>20 °C) also contributed to longer search times. In order to make quick decisions and attain success during SAR operations, authorities responsible for SAR missions must have a sound knowledge of the locomotor characteristics and skill level (certification level) of SAR dogs in relation to terrain and environmental conditions.

Peking geckos (Gekko swinhonis) traversing upward steps: the effect of step height on the transition from horizontal to vertical locomotion.

The ability to transition between surfaces (e.g., from the ground to vertical barriers, such as walls, tree trunks, or rock surfaces) is important for the Peking gecko's (Gekko swinhonis Günther 1864) survival. However, quantitative research on gecko's kinematic performance and the effect of obstacle height during transitional locomotion remains scarce. In this study, the transitional locomotion of geckos facing different obstacle heights was assessed. Remarkably, geckos demonstrated a bimodal locomotion ability, as they could climb and jump. Climbing was more common on smaller obstacles and took longer than jumping. The jumping type depended on the obstacle height: when geckos could jump onto the obstacle, the vertical velocity increased with obstacle height; however, geckos jumped from a closer position when the obstacle height exceeded this range and would get attached to the vertical surface. A stability analysis of vertical surface landing using a collision model revealed that geckos can reduce their restraint impulse by increasing the landing angle through limb extension close to the body, consequently dissipating collision energy and reducing their horizontal and vertical velocities. The findings of this study reveal the adaptations evolved by geckos to move in their environments and may have applicability in the robotics field.

An In-Pipe Inspection Robot with Permanent Magnets and Omnidirectional Wheels: Design and Implementation

This paper aims to present the design and prototype of an inspection robot that can perform both horizontal and vertical locomotion in ferromagnetic pipelines. The proposed robot applies to a range from 5-inch (127 mm) diameter pipes to flat plates. The train-like robot is mainly composed of three sealed modules with omnidirectional driving wheels for longitudinal and transverse movements. Permanent magnets were designed to provide sufficient magnetic adhesion between the robot and the ferromagnetic surface of the pipes. The internal condition of the pipe can be monitored visually through cameras and sensors. Specific experimental conditions have been carried out to validate the robot’s capabilities, including maximum speed, payload capacity, and vertical climbing distance. The experimental results also show that the robot is capable of passing through a straight pipe and elbow fitting in both upward and downward directions.

Climbing parrots achieve pitch stability using forces and free moments produced by axial-appendicular couples.

During vertical climbing, the gravitational moment tends to pitch the animal's head away from the climbing surface and this may be countered by (1) applying a correcting torque at a discrete contact point, or (2) applying opposing horizontal forces at separate contact points to produce a free moment. We tested these potential strategies in small parrots with an experimental climbing apparatus imitating the fine branches and vines of their natural habitat. The birds climbed on a vertical ladder with four instrumented rungs that measured three-dimensional force and torque, representing the first measurements of multiple contacts from a climbing bird. The parrots ascend primarily by pulling themselves upward using the beak and feet. They resist the gravitational pitching moment with a free moment produced by horizontal force couples between the beak and feet during the first third of the stride and the tail and feet during the last third of the stride. The reaction torque from individual rungs did not counter, but exacerbated the gravitational pitching moment, which was countered entirely by the free moment. Possible climbing limitations were explored using two different rung radii, each with low and high friction surfaces. Rung torque was limited in the large-radius, low-friction condition; however, rung condition did not significantly influence the free moments produced. These findings have implications for our understanding of avian locomotor modules (i.e. coordinated actions of the head-neck, hindlimbs and tail), the use of force couples in vertical locomotion, and the evolution of associated structures.

Vertical locomotion in the arboreal salamander Aneides vagrans

AbstractSalamanders are often used as a model of early tetrapod locomotion, due to their generalized tetrapod body plan. We imaged five individuals of wandering salamander, Aneides vagrans, during horizontal and vertical locomotion and compared kinematic and gait adjustments made to compensate for each condition. We used ImageJ to calculate duty factor, stride length, stride frequency, contralateral foot spread, heading of climbing, and forward velocity. Like other terrestrial salamanders, A. vagrans use a diagonal couplet, lateral sequence walk on horizontal surfaces. When walking vertically, however, they use a single‐foot gait, taking smaller steps and extending the duty factor compared with level walking. Salamanders adjusted their limbs to have a wider contralateral foot spread between fore‐ and hindfeet when walking downward as compared to walking upward or horizontally. These gait adjustments may minimize the risk of slipping or falling by increasing the number of contact points during the stride cycle, and by bringing their center of mass closer to the surface. We found that salamanders moved at a significantly faster velocity when traveling horizontally compared to vertically. Furthermore, we found no significant difference between upward and downward velocity, despite greater stride lengths in upward locomotion; this was explained by a higher stride frequency in downward locomotion. We estimate travel time up or down an old‐growth redwood tree to be on the scale of hours, a significant time investment that may encourage alternatives when available. These results suggest that, in an ecological context, while salamanders are capable of traveling straight down a redwood tree, they may simply tend to jump.

A primal role for the vestibular sense in the development of coordinated locomotion.

Mature locomotion requires that animal nervous systems coordinate distinct groups of muscles. The pressures that guide the development of coordination are not well understood. To understand how and why coordination might emerge, we measured the kinematics of spontaneous vertical locomotion across early development in zebrafish (Danio rerio) . We found that zebrafish used their pectoral fins and bodies synergistically during upwards swims. As larvae developed, they changed the way they coordinated fin and body movements, allowing them to climb with increasingly stable postures. This fin-body synergy was absent in vestibular mutants, suggesting sensed imbalance promotes coordinated movements. Similarly, synergies were systematically altered following cerebellar lesions, identifying a neural substrate regulating fin-body coordination. Together these findings link the vestibular sense to the maturation of coordinated locomotion. Developing zebrafish improve postural stability by changing fin-body coordination. We therefore propose that the development of coordinated locomotion is regulated by vestibular sensation.

Laying hen’s mobility is impaired by keel bone fractures and does not improve with paracetamol treatment

Keel bone fractures (KBF) in laying hens pose a severe problem for animal welfare as they are likely to be associated with pain and suffering. Furthermore, they are suspected to hinder or restrict hens in their performance of natural species-specific behaviour. The aim of this study was to determine whether KBF affect laying hen behaviour in a non-cage system and whether this alteration is caused by pain. Forty Brown Nick and 40 Nick Chick hens were individually marked, and video recorded in eight experimental pens containing two perches with a platform attached to a ramp to facilitate access, an elevated nest box with platform for landing, drinker, feeder and litter. Data was collected at 37 and 39 weeks of age (WoA) on two consecutive days each at three time points per day. Paracetamol was administrated via drinking water either during the 37th or the 39th WoA. Additionally, activity assessments were done at 26, 28, and 30 WoA to detect differences pre-fracture. To assess the keel bone (KB) state, hens were radiographed at 30, 37 and 39 WoA and KB categorised as having no fracture, healed fracture(s) or fractures with a visible fracture gap. The odds of perch or nest access (i.e., vertical locomotion) decreased when a fracture gap was visible (p = 0.004) but the walking pace on ramps leading to the perches was not affected by KBF. Paracetamol did neither reverse the decrease in mobility behaviour nor did it affect the walking pace on the ramp. Of the hens with fractures featuring a visible fracture gap, those receiving paracetamol performed less rapid comfort behaviours (e.g., wing flapping) than hens receiving vehicle (i.e. water) only (p = 0.04). Preening and dustbathing duration was increased with the administration of paracetamol (p = 0.02) though was unaffected by KBF in this study. No difference was found in activity before the fracture(s) occurred. In conclusion, we show that KBF affect laying hen mobility behaviour in non-cage systems and thus a reduction of KBF would improve laying hen welfare.

Chemogenetic Targeting of Dorsomedial Direct-pathway Striatal Projection Neurons Selectively Elicits Rotational Behavior in Mice

The striatum of the basal ganglia is pivotal for voluntary movements and is implicated in debilitating movement disorders such as Parkinsonism and dystonia. Striatum projects to downstream nuclei through direct (dSPN) and indirect (iSPN) pathway projection neurons thought to exert opposite effects on movement. In rodent models of striatal function, unilateral dopamine deprivation induces ipsiversive rotational behavior. The dSPNs of the dorsal striatum are believed to engage distinct motor programs but underlying mechanisms remain unclear. Here, we show by employing chemogenetics [Designer Receptors Exclusively Activated by Designer Drugs (DREADDs)] that unilateral inhibition of dorsomedial dSPNs is sufficient to selectively impair contraversive movement and elicit ipsiversive rotational behavior in mice. Adeno-associated virus (AAV) encoding Cre-dependent Gi-coupled DREADD was injected unilaterally into the dorsomedial striatum of Drd1-Cre mice, resulting in expression of the modified human M4 muscarinic receptor (hM4Di) in ∼20% of dorsostriatal dSPNs. Upon hM4Di activation, a striking positive linear correlation was found between turn ratio and viral expression, which corroborates a relationship between unilateral inhibition of dorsomedial dSPNs and rotational behavior. Bursts of ipsiversive rotations were interspersed with normal ambulation. However, partial unilateral inhibition of ∼20% of dorsostriatal dSPNs did not affect horizontal and vertical locomotion or forelimb use preference. Overall, our results substantiate a unique role of dSPNs in promoting response bias in rotational behavior and show this to be a highly sensitive measure of dSPN performance.

Analysis of Reaction Force and Locomotor Behavior on Geckos in Time- and Frequency-domain during Climbing on Vertical Substrates

Since the commencement of climbing robots, the moving ability of climbing robots has continuously lagged far behind that of climbing animal. A primary cause is the insufficient understanding of how animals govern their climbing locomotion. To reveal the mechanism of vertical locomotion and enhance the performance of climbing robots, we have measured the reaction forces acting on climbing geckos and recorded the locomotor behaviors synchronously. The coordinates of reference points were regressed to analyze kinematic feature factors. Meanwhile, the data of reaction forces were further processed by fast Fourier transform and wavelet transform to acquire time-frequency domain characteristics. The results show a good agreement between the reaction forces and the locomotor behaviors in time-frequency domain; the main locomotor frequency of trunk in fore-aft direction is twice that in lateral direction; the excellent adhesion system of geckos enables them to climbing up vertical substrate with not only a very tiny impact in time scale but also not easily identifiable characteristics in frequency-domain. Above research will help deepen our understanding of the climbing locomotion, and provide a more precise prototype for the design of gecko-like robot.

Способ моделирования эмоционального стресса “дефицита времени”

The technique for modeling the «time deficit» emotional stress (TDS) was proposed in the experiment on 40 mature male white outbred rats (weight 220-240 g), its stressing effect was compared to that of the «free swimming in a cage» model. To achieve the TDS, individual rats were placed in a spiral-shaped tube that was quickly filled with water, which forced the rat to quickly move upwards. The classical signs of stress were observed — increased adrenal gland relative weight (31%), decreased thymus and spleen weight (26 and 14%), damaged stomach lining (in 80% of animals: 1st grade in 20% of rats, 2nd or 3rd grade in the other 60%, in 1:1 ratio; hemorrhage abundance: 2 hemorrhages for animal in 30%, 3 in 40%, 4 in 10% of rats, damage index: 4.7), altered serum corticosteroids (increased by 43%) and insulin (decreased by 19%) concentrations, activation of thyroid function (increased total and free triiodothyronine and thyroxine concentrationsin the blood by 18-32%). The horizontal locomotion and physical endurance were increased in animals following the TDS, whereas their vertical locomotion decreased as they developed anxiety. In comparison with the existing models, the proposed technique of the emotional stress modeling allows for the individual testing of animals, provides total removal of their waste and does not involve the physical trauma, which allows for the more objective studies of the mechanisms of stress injure development.

Inverted and vertical climbing of a quadrupedal microrobot using electroadhesion.

The ability to climb greatly increases the reachable workspace of terrestrial robots, improving their utility for inspection and exploration tasks. This is particularly desirable for small (millimeter-scale) legged robots operating in confined environments. This paper presents a 1.48-gram and 4.5-centimeter-long tethered quadrupedal microrobot, the Harvard Ambulatory MicroRobot with Electroadhesion (HAMR-E). The design of HAMR-E enables precise leg motions and voltage-controlled electroadhesion for repeatable and reliable climbing of inverted and vertical surfaces. The innovations that enable this behavior are an integrated leg structure with electroadhesive pads and passive alignment ankles and a parametric tripedal crawling gait. At a relatively low adhesion voltage of 250 volts, HAMR-E achieves speeds up to 1.2 (4.6) millimeters per second and can ambulate for a maximum of 215 (162) steps during vertical (inverted) locomotion. Furthermore, HAMR-E still retains the ability for high-speed locomotion at 140 millimeters per second on horizontal surfaces. As a demonstration of its potential for industrial applications, such as in situ inspection of high-value assets, we show that HAMR-E is capable of achieving open-loop, inverted locomotion inside a curved portion of a commercial jet engine.

Hand pressures during arboreal locomotion in captive bonobos (Pan paniscus).

Evolution of the human hand has undergone a transition from use during locomotion to use primarily for manipulation. Previous comparative morphological and biomechanical studies have focused on potential changes in manipulative abilities during human hand evolution, but few have focused on functional signals for arboreal locomotion. Here, we provide this comparative context though the first analysis of hand loading in captive bonobos during arboreal locomotion. We quantify pressure experienced by the fingers, palm and thumb in bonobos during vertical locomotion, suspension and arboreal knuckle-walking. The results show that pressure experienced by the fingers is significantly higher during knuckle-walking compared with similar pressures experienced by the fingers and palm during suspensory and vertical locomotion. Peak pressure is most often experienced at or around the third digit in all locomotor modes. Pressure quantified for the thumb is either very low or absent, despite the thumb making contact with the substrate during all suspensory and vertical locomotor trials. Unlike chimpanzees, bonobos do not show a rolling pattern of digit contact with the substrate during arboreal knuckle-walking - instead, we found that digits 3 and 4 typically touch down first and digit 5 almost always made contact with the substrate. These results have implications for interpreting extant and fossilized hand morphology; we expect bonobo (and chimpanzee) bony morphology to primarily reflect the biomechanical loading of knuckle-walking, while functional signals for arboreal locomotion in fossil hominins are most likely to appear in the fingers, particularly digit 3, and least likely to appear in the morphology of the thumb.

Locomotor effects of a low-frequency fire alarm on C57BL/6 male mice: a preliminary study

Maintaining appropriate acoustic conditions for animal welfare and data collection are crucial in biomedical research facilities. Negative impacts of disruptive sound are known and can include auditory damage, immune function changes, and behavioral alterations. One type of disruptive sound occurring in research facilities is that of fire alarms. To ameliorate this problem, many facilities have incorporated the use of low-frequency fire alarms that emit tones outside the rodent audible range. The impact of these devices has been assumed to be negligible. However, this has yet to be evaluated with controlled behavioral experiments. Thus, our objective was to investigate the impact of low-frequency fire alarm exposure on locomotor behavior in the open field, a test sensitive to acoustic stimuli disruption. Male mice were randomized to three alarm exposure groups (No-Alarm; Alarm-During; and Alarm-After) and placed in individual photobeam-activated locomotor chambers. The Alarm-During group displayed significantly reduced horizontal locomotion, with a trend towards reduced vertical locomotion. These data suggest that a low-frequency brief alarm tone can temporarily disrupt movement, a valuable insight should an alarm be deployed. Further, findings support close collaboration between researchers and institutional facility staff to ensure appropriate acoustic conditions are maintained, whenever possible, for research animals.