Limbs In Locomotion Research Articles

Anatomical and molecular analyses of the deltoid muscle in chimpanzees (Pan troglodytes) and modern humans (Homo sapiens): Similarities and differences due to the uses of the upper extremity.

In the deltoid muscles of Pan troglodytes and Homo sapiens, we have analyzed the muscle architecture and the expression of the myosin heavy chain (MHC) isoforms. Our aim was to identify differences between the two species that could be related to their different uses of the upper limb. The deltoid muscle of six adult Pan troglodytes and six adult Homo sapiens were dissected. The muscle fascicle length (MFL) and the physiological cross-sectional area (PCSA) of each muscle were calculated in absolute and normalized values. The expression pattern of the MHC-I, MHC-IIa and MHC-IIx isoforms was analyzed in the same muscles by real-time polymerase chain reaction. Only the acromial deltoid (AD) presented significant architectural differences between the two species, with higher MFL values in humans and higher PCSA values in chimpanzees. No significant differences in the expression pattern of the MHC isoforms were identified. The higher PCSA values in the AD of Pan troglodytes indicate a greater capacity of force generation in chimpanzees than in humans, which may be related to a greater use of the upper limb in locomotion, specifically in arboreal locomotion like vertical climbing. The functional differences between chimpanzees and humans in the deltoid muscle are more related to muscle architecture than to a differential expression of MHC isoforms.

Cortical connections of the functional domain for climbing or running in posterior parietal cortex of galagos.

Previous studies in prosimian galagos (Otolemur garnetti) have demonstrated that posterior parietal cortex (PPC) is subdivided into several functionally distinct domains, each of which mediates a specific type of complex movements (e.g., reaching, grasping, hand-to-mouth) and has a different pattern of cortical connections. Here we identified a medially located domain in PPC where combined forelimb and hindlimb movements, as if climbing or running, were evoked by long-train intracortical microstimulation. We injected anatomical tracers in this climbing/running domain of PPC to reveal its cortical connections. Our results showed the PPC climbing domain had dense intrinsic connections within rostral PPC and reciprocal connections with forelimb and hindlimb region in primary motor cortex (M1) of the ipsilateral hemisphere. Fewer connections were with dorsal premotor cortex (PMd), supplementary motor (SMA), and cingulate motor (CMA) areas, as well as somatosensory cortex including areas 3a, 3b, and 1-2, secondary somatosensory (S2), parietal ventral (PV), and retroinsular (Ri) areas. The rostral portion of the climbing domain had more connections with primary somatosensory cortex than the caudal portion. Cortical projections were found in functionally matched domains in M1 and premotor cortex (PMC). Similar patterns of connections with fewer labeled neurons and terminals were seen in the contralateral hemisphere. These connection patterns are consistent with the proposed role of the climbing/running domain as part of a parietal-frontal network for combined use of the limbs in locomotion as in climbing and running. The cortical connections identify this action-specific domain in PPC as a more somatosensory driven domain.

Motor flexibility in insects: adaptive coordination of limbs in locomotion and near-range exploration

In recent years, research on insect motor behaviour―locomotion in particular―has provided a number of important new insights, many of which became possible because of methodological advances in motion capture of unrestrained moving insects. Behavioural analyses have not only backed-up neurophysiological analyses of the underlying mechanisms at work, they have also highlighted the complexity and variability of leg movements in naturalistic, unrestrained behaviour. Here, we argue that the variability of unrestrained motor behaviour should be considered a sign of behavioural flexibility. Assuming that variation of movement-related parameters is governed by neural mechanisms, behavioural analyses can complement neurophysiological investigations, for example by (i) dissociating distinct movement episodes based on functional and statistical grounds, (ii) quantifying when and how transitions between movement episodes occur, and (iii) dissociating temporal and spatial coordination. The present review emphasises the importance of considering the functional diversity of limb movements in insect behaviour. In particular, we highlight the fundamental difference between leg movements that generate interaction forces as opposed to those that do not. On that background, we discuss the spatially continuous modulation of swing movements and the quasi-rhythmic nature of stepping across insect orders. Based on examples of motor flexibility in stick insects, we illustrate the relevance of behaviour-based approaches for computational modelling of a rich and adaptive movement repertoire. Finally, we emphasise the intimate interplay of locomotion and near-range exploration. We propose that this interplay, through continuous integration of distributed, multimodal sensory feedback, is key to locomotor flexibility.

Model of a bilateral Brown-type central pattern generator for symmetric and asymmetric locomotion.

The coordinated activity of muscles is produced in part by spinal rhythmogenic neural circuits, termed central pattern generators (CPGs). A classical CPG model is a system of coupled oscillators that transform locomotor drive into coordinated and gait-specific patterns of muscle recruitment. The network properties of this conceptual model can be simulated by a system of ordinary differential equations with a physiologically inspired coupling locus of interactions capturing the timing relationship for bilateral coordination of limbs in locomotion. Whereas most similar models are solved numerically, it is intriguing to have a full analytical description of this plausible CPG architecture to illuminate the functionality within this structure and to expand it to include steering control. Here, we provided a closed-form analytical solution contrasted against the previous numerical method. The evaluation time of the analytical solution was decreased by an order of magnitude when compared with the numerical approach (relative errors, <0.01%). The analytical solution tested and supported the previous finding that the input to the model can be expressed in units of the desired limb locomotor speed. Furthermore, we performed parametric sensitivity analysis in the context of controlling steering and documented two possible mechanisms associated with either an external drive or intrinsic CPG parameters. The results identify specific propriospinal pathways that may be associated with adaptations within the CPG structure. The model offered several network configurations that may generate the same behavioral outcomes. NEW & NOTEWORTHY Using a simple process of leaky integration, we developed an analytical solution to a robust model of spinal pattern generation. We analyzed the ability of this neural element to exert locomotor control of the signal associated with limb speeds and tested the ability of this simple structure to embed steering control using the velocity signal in the model's inputs or within the internal connectivity of its elements.

Transection method for shortening the rat spine and spinal cord

Previous studies have presented evidence which indicates that the regeneration of axons in the spinal cord occurs following spinal cord transection in young rats. However, in a transection-regeneration model, the completeness of the transection is often a matter of dispute. We established a method for shortening the rat spine and spinal cord to provide a spinal cord injury (SCI) model in which there was no doubt about whether the axonal transection was complete. In the future, this model may be applied to the chronic period of complete paralysis following SCI. Adult, female Wistar rats (220–250g) were used in the study. The spinal cord was exposed and a 4-mm-long segment of the spinal cord was removed at Th8. Subsequently, the Th7/8 and Th8/9 discs were cut between the stumps of the spinal cord to remove the Th8 vertebra. The stitches which had been passed through the 7th and 9th ribs bilaterally were tied gradually to bring together the stumps of the spinal cord. Almost all the rats survived until the end of the experiment. Uncoordinated movements of the hind limbs in locomotion were observed at 4 weeks after surgery. However coordinated movements of the hind limbs in locomotion were not observed until the end of the experiment. After 12 weeks, an intracardiac perfusion was performed to remove the thoracic spine and the spinal cord. There were no signs of infection. The bone fusion of the Th7 and Th9 vertebrae was observed to be complete in all specimens and the alignment of the thoracic spine was maintained. The spinal canal was also correctly reconstituted. The stumps of the spinal cord were connected. Light microscopy of the cord showed that scar tissue intervened at the connection site. Cavitation inhibiting the axonal regeneration was also observed. This model was also made on the assumption that glial scar tissue inhibits axonal regeneration in chronic SCI. Axonal regeneration was not observed across the transected spinal cord in this model. Attempts should be made to minimize the damage to the spinal cord and the surgery time for successful axonal regeneration to occur. The model developed in this study may be useful in the study of axonal regeneration in SCI.

Shank–foot complex 2-D kinematics during stance using markerless segmentation and body-segment anatomical axes identification

Shank and foot complex is considered to be a fundamental mechanism of the lower limb in locomotion. Typically marker based techniques are used to analyze the shank and foot kinematics. Three markers per segment are mounted. The disadvantages of this technique are the complexity stemming from the number of markers per segment and the interference of markers with the subject and the subject’s movement. In this work, a markerless approach, which uses the 2-D images acquired by a digital camera, is proposed. The shank-foot complex is defined as a three-segment model by applying image processing techniques to the images of a subject walking in both barefoot and socked conditions. The aims of the current technique can be summarized as: (1) to ease the process of data acquisition by eliminating the markers and including the possibility of wearing socks; (2) to track the shank–foot complex kinematics with a three-segmented model.

The tri‐segmented limbs of therian mammals: kinematics, dynamics, and self‐stabilization—a review

The evolution of therian mammals is to a large degree marked by changes in their motion systems. One of the decisive transitions has been from the sprawled, bi-segmented to the parasagittal, tri-segmented limb. Here, we review aspects of the tri-segmented limb in locomotion which have been elucidated in our research groups in the last 10 years. First, we report the kinematics of the tri-segmented therian limb from mouse to elephant in order to explore general principles of the therian limb configuration and locomotion. Torques will be reported from a previous paper (Witte et al., 2002. J Exp Biol 205:1339-1353) for a better understanding of the anti-gravity work of all limb joints. The stability of a limb in z-configuration will be explained and its advantage with respect to other potential solutions from modeling will be discussed. Finally, we describe how the emerging concept of self-stability can be explained for a tri-segmented leg template and how it affects the design of the musculoskeletal system and the operation of legs during locomotion. While locomotion has been considered as mainly a control problem in various disciplines, we stress the necessity to reduce control as much as possible. Central control can be cheap if the limbs are "intelligent" by means of their design. Gravity-induced movements and self-stability seem to be energy-saving mechanisms.

Simultaneous bilateral 3-D able-bodied gait

This paper reports on the muscle powers and mechanical energies developed during gait by the lower limbs over two consecutive cycles. Nineteen male able-bodied subjects participated in this study. An 8-camera video system filmed the subjects bilaterally as they walked at their natural speed over two force plates. A 3-dimensional inverse dynamic analysis was carried out to determine joint moments, powers and mechanical energy at each joint and in all planes for a total of 57 trials. The walking speed (1.30 m/s), the cadence (106.5 steps/min) and the stance phase relative duration (60.7% of the gait cycle) of the right limb were not significantly different from those of the left limb. The limb muscle peak powers were mostly different in the sagittal plane and reflected gait adjustments rather than asymmetry in gait. Generally, these differences occurred during absorption bursts. The total positive work was similar for both limbs and was associated with maintaining a similar walking speed for each limb. The right limb developed a significantly greater total negative work than the left limb. This was associated with the control of the lower limb in locomotion.

Behavioral laterality in captive bonobos (Pan paniscus): Replication and extension

We report observational data on behavioral laterality in 10 captive bonobos (Pan paniscus)at the San Diego Zoo. The unimanual measures include carrying, leading limb in locomotion, self-touching, face-touching, reaching, and gestures. We also recorded bimanual feeding in these subjects. A significant population level left-hand bias exists for carrying. Right-hand biases occur for leading limb in locomotion and gestures. During bimanual feeding, the bonobos hold food items with the left hand while feeding with the right hand. Overall, bonobos exhibit behavioral asymmetries that are similar to previous findings in other pongid ape species. The asymmetries in gestures and bimanual feeding represent novel findings with theoretical implications for the origins of tool use and language.

How the horse moves: 2. Significance of graphical representations of equine hind limb kinematics.

Kinematic data of the equine hind limb are presented graphically and related to functional aspects of the hind limb in locomotion. The trot of 24 two-year-old Dutch Warmblood horses was recorded at 4 m/s on a high-speed treadmill using kinematic analysis equipment. Joint angle-time, angle-angle, stick and marker diagrams were used to present graphically the data following standardised procedures. As the kinematic data were expressed with reference to the joint angles of the horse standing squarely and were time-standardised to the duration of the stride cycle, mean joint curves for the total group could be calculated and therefore describe the function of the different segments of the equine hind limb. The motion of the hind limb in the sagittal plane appeared to be pendular around a rotation point in the acetabulum. During the stance phase the extension of the fetlock joint and stance flexion of the stifle, tarsal and coffin joints illustrate the shock absorption of the hind limb. In the swing phase the reciprocal apparatus, which forms the coupling mechanism between stifle and tarsal joint, also influences the fetlock joint because synchronous flexion and extension between these 3 joints were demonstrated. By graphically presenting hind limb motion we were able to illustrate the relation between kinematics and function. This graphic analysis can be used in clinical studies involving quantification of equine hind limb coordination in the sagittal plane.

Fossil Evidence for the Origin of Aquatic Locomotion in Archaeocete Whales

Recent members of the order Cetacea (whales, dolphins, and porpoises) move in the water by vertical tail beats and cannot locomote on land. Their hindlimbs are not visible externally and the bones are reduced to one or a few splints that commonly lack joints. However, cetaceans originated from four-legged land mammals that used their limbs for locomotion and were probably apt runners. Because there are no relatively complete limbs for archaic archaeocete cetaceans, it is not known how the transition in locomotory organs from land to water occurred. Recovery of a skeleton of an early fossil cetacean from the Kuldana Formation, Pakistan, documents transitional modes of locomotion, and allows hypotheses concerning swimming in early cetaceans to be tested. The fossil indicates that archaic whales swam by undulating their vertebral column, thus forcing their feet up and down in a way similar to modern otters. Their movements on land probably resembled those of sea lions to some degree, and involved protraction and retraction of the abducted limbs.

The role of the tail in channel passage by the sand skink, Neoseps reynoldsi

AbstractThirteen sand skinks, Neoseps reynoldsi, were observed and videotaped traversing variously spaced plexiglass channels and spacings of pins to investigate locomotory patterns of a slender elongate lizard, with reduced limbs. Five individuals were recorded both before and after tail autotomy. Neoseps moves its limbs in locomotion on a flat surface; the hindlimbs participate in propulsion and their position, relative to their body, reflects the curvature of the trunk. Distance between pins, width of the plexiglass channel, and surface texture influence locomotory patterns. Individuals move more rapidly in wide channels, and movement is most irregular in channels with sandpaper floors. Whether on a plexiglass or a sandpaper floor, individuals travel more rapidly down the 2cm wide channel than the 1 cm channel. Fewer bends in the trunk in the wider channels may allow for more rapid movement. Autotomy of the tail slows movement on a plexiglass or sandpaper floor. The anterior portion of the tail contributes to the establishment of a static friction site that is jerked toward the head during locomotion, advancing the center of gravity in that direction. From the new site the trunk can be straightened by pushing against the friction site. The posterior portion of a tailless individual slides backward as the trunk is straightened, slowing their forward movement. The backward slide may reflect the lower mass and reduced static friction of the partial tail. In channels, Neoseps uses limbed concertina rather than simple concertina to generate a propulsive force. Evolutionarily, it appears that elongation of the tail and trunk did not incorporate the capacity for lateral undulation; as the curves of the trunk and tail seem preprogrammed and do not adjust to local points of contact.

Composition of myofiber types in limb muscles of the house shrew (Suncus murinus): Lack of type I myofibers

Postural muscles have many type I myofibers, which reacted strongly for acid-stable myosin ATPase and were unreactive for alkali-stable myosin ATPase (Ariano et al., J. Histochem. Cytochem., 21:51-55, 1973; Armstrong et al., Am. J. Anat., 163:87-98, 1982; Smith et al., J. Neurophysiol., 40:503-513, 1977). House shrews (Suncus murinus) keep abducting their limbs in locomotion and hardly lift their trunk off the ground. The limb muscles of Suncus were examined by histochemical methods to determine whether the locomotory and postural behavior is related to the proportion of type I myofibers. The observation of whole cross sections from the triceps surae, flexor digitorum superficialis, quadriceps femoris, and caudally situated muscles in the thigh showed that all myofibers of these muscles were unreactive for acid-stable myosin ATPase and strongly reactive for alkali-stable myosin ATPase: Those were classified as type II myofibers. Type II myofibers showed a weak (type IIB), moderate (type IIAB), or strong (type IIA) reaction for NADH tetrazolium reductase. Part of type IIA myofibers reacted weakly to moderately for menadione-linked glycerol-3-phosphate dehydrogenase (m-GPD), which predominated in the soleus muscle. Type IIAB, type IIB, and the remainder of type IIA myofibers reacted strongly for m-GPD. The limb muscles contained subtypes of type II myofibers but no type I myofibers. In Suncus murinus, type I myofibers specialized for a postural maintenance may not be required because all myofibers function exclusively for propulsion.

Hind Limbs of Eocene Basilosaurus: Evidence of Feet in Whales

New specimens of middle Eocene Basilosaurus isis from Egypt include the first functional pelvic limb and foot bones known in Cetacea. These are important in corroborating the intermediate evolutionary position of archaeocetes between generalized Paleocene land mammals that used hind limbs in locomotion and Oligocene-to- Recent whales that lack functional pelvic limbs. The foot is paraxonic, consistent with derivation from mesonychid Condylarthra. Hind limbs of Basilosaurus are interpreted as copulatory guides.

Ipsilateral limb variation in cats during overground locomotion.

The timing interval between the onset of knee extensor EMG (vastus lateralis) and the onset of the ipsilateral elbow flexor EMG (brachialis) was studied in adult cats during overground walking, trotting and galloping. Concurrent finding of the animals in locomotion was used to relate the electrical activity of the muscles to the physical events in a step cycle. The observed variability in the interval between the onset of knee extensor EMG and the onset of elbow flexor EMG lead to the conclusion that it is not appropriate to postulate a rigid neural coupling mechanism for the control and coordination of ipsilateral limbs in locomotion.

Coordination of movements of the hindlimbs and forelimbs in different forms of locomotion in normal and decerebrate cats

The coupling of movements of the hindlimbs and forelimbs has been analysed in intact cats stepping overground and on a treadmill and during swimming, and in decerebrate cats stepping on a treadmill, immersed in water('swimming') and stepping suspended in the air. In the different preparations, and under different types of locomotion, two basic patterns of coupling have been observed. Both concern the hindlimb and forelimb of the same side of the body. The first pattern is found in the pacing gait where flexion of the forelimb precedes extension of the hindlimb, measured at the elbow and knee, respectively. The second pattern is typically found in the trot where flexion of the forelimb follows extension of the hindlimb. In decerebrate cats both patterns of coupling remain after bilateral deafferentation of the hindlimbs. In the alternate form of locomotion these patterns of coupling occurs symmetrically on both sides. In the rotatory and transverse gallop (examples of the in-phase form of locomotion) the coupling is asymmetrical: on one side it is comparable to pacing (forelimb flexion precedes hindlimb extension), and on the other side to trotting (forelimb flexion follows extension). These basic patterns of interlimb coordination simplify considerably the problem of neural control of the limbs in locomotion. Obersations of EMGs during the alternative forms of locomotion show that in the pacing type of coupling the extensor EMGs of forelimb and hindlimb overlap, with the hindlimb leading the forelimb by about 10% of a step cycle, while in the trotting type of coupling the forelimb flexor EMGs overlap the hindlimb extensor EMGs, the forelimb flexors leading the hindlimb extensors by about 10% of a step cycle. During acceleration the transition between the two forms of EMG occurs within one or two step cycles, and at some intermediate velocities the EMG coupling springs back and forth between the two different forms. These results further support the hypotesis of two basic forms of interlimb coupling in which long propriospinal pathways probably play a role.