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Results for “interlimb coordination”

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PubMed2003

Bimanual training reduces spatial interference.

The authors investigated whether training can reduce bimanual directional interference by using a star-line drawing paradigm. Participants (N = 30) were required to perform rhythmical arm movements with identical temporal but differing directional demands. Moreover, the effectiveness of part-task training in which each movement was practiced in isolation was compared with that of whole-task training in which only combined movements were performed. Findings revealed that bimanual training substantially reduced spatial interference, but unimanual training did not. The authors therefore concluded that the spatial coupling of the limbs is not implemented in a rigid way; instead, the underlying neural correlate can undergo plastic changes induced by training. Moreover, the practical implication that emerged from the present study is that athletic, musical, or ergonomic skills that require a high degree of interlimb coordination are best served by whole-task practice.

Adult↗

PubMed1985

Mathematical models of central pattern generators in locomotion: I. Current problems.

As a background for subsequent studies of mathematical models of central pattern generators in locomotion (Stafford & Barnwell, 1985a, b) relevant aspects of the literature on locomotion are reviewed, concepts of locomotion discussed, and extant models considered. Advantages and disadvantages of present models are discussed, and the need for mathematical models is emphasized. It is shown that realistic models of pattern generation in locomotion must take numerous factors into account, including phases of step cycle, muscle sequencing, gait and interlimb coordination, initiation and cessation of locomotion, and many aspects of neuromuscular control and function.

Journal Article↗

PubMed1989

An analysis of air-stepping in normal infant vervet monkeys.

Limb movements during air-stepping were analyzed in three neonatal vervet monkeys over a three-week period. The movements had similar temporal organization both across animals and across time. For example, the duration of both the hind and the forelimb cycle equaled about 500 ms, with hind limb return strokes lasting much longer than the hind limb power strokes. Furthermore, there were clear indications of both intra- and interlimb coordination. Specifically, all the joints of a limb tended to flex and extend simultaneously, and contralateral and ipsilateral limb pairs had an average phase relationship of approximately 50% of cycle duration. Despite a qualitative similarity between limb movements during air-stepping in the neonates and overground locomotion in older animals, there were notable differences both in temporal relationships and joint displacement patterns. Finally, there appeared to be important similarities between air-stepping in these monkeys and stepping in newborn humans. Most notably, both tended to disappear after a limited period. The implications of these similarities, as well as the overall results, are discussed in relation to the understanding of the development of locomotor behavior in human and nonhuman primates, using approaches based both upon the hard-wired and dynamic models.

Journal Article↗

PubMed1991

Note: A statistical problem in testing invariance of movement using the phase plane model.

Invariant positions on a phase plane of joint angular position and velocity have been proposed as a means by which interlimb coordination may be achieved. This note identifies a problem in the testing, using conventional statistics, of hypotheses derived using the phase plane model. A possible solution is proposed based on directional statistics. Conclusions regarding phase angle invariance, which are based on conventional statistics, must be viewed with some caution.

Journal Article↗

PubMed2001

Automated quantitative gait analysis during overground locomotion in the rat: its application to spinal cord contusion and transection injuries.

Analysis of locomotion is an important tool in the study of peripheral and central nervous system damage. Most locomotor scoring systems in rodents are based either upon open field locomotion assessment, for example, the BBB score or upon foot print analysis. The former yields a semiquantitative description of locomotion as a whole, whereas the latter generates quantitative data on several selected gait parameters. In this paper, we describe the use of a newly developed gait analysis method that allows easy quantitation of a large number of locomotion parameters during walkway crossing. We were able to extract data on interlimb coordination, swing duration, paw print areas (total over stance, and at 20-msec time resolution), stride length, and base of support: Similar data can not be gathered by any single previously described method. We compare changes in gait parameters induced by two different models of spinal cord injury in rats, transection of the dorsal half of the spinal cord and spinal cord contusion injury induced by the NYU or MASCIS device. Although we applied this method to rats with spinal cord injury, the usefulness of this method is not limited to rats or to the investigation of spinal cord injuries alone.

Abdomen↗

PubMed2001

Kinematic analyses of air-stepping of neonatal rats after mid-thoracic spinal cord compression.

Although human infants suffer traumatic spinal cord injury, appropriate animal models have not been developed. The consequences of neonatal injury are not necessarily the same as in adults, so treatments designed for adults may not generalize to infants. Therefore, understanding the effects of traumatic injury to the developing cord is important. In this experiment, mid-thoracic spinal cords of 4-day-old rats were compressed with forceps by 0% (sham), 90% or 95% of the uncompressed width. On postoperative day (POD) 1 or 11, rats were suspended in harnesses and administered L-DOPA to activate locomotor circuits. Slight modifications of interlimb coordination remained on POD 11 following the lesser compression, whereas the amount of hindlimb air-stepping, step rates, step lengths and coordination were reduced and declined post-operatively following the greater compression. Lesions were proportional to severity of compression. Progressive motor dysfunction during air-stepping revealed deficits in descending control of lumbar circuits, whereas previous reports of recovery of overground walking probably reflect activation of reflex mechanisms caudal to the transection.

Animals↗

PubMed2006

Quantification of locomotor recovery following spinal cord contusion in adult rats.

Injury to the spinal cord not only disrupts the functioning of spinal circuits at the site of the impact, but also limits sensorimotor function caudal to the level of the lesion. Ratings of gross locomotor skill are generally used to quantify locomotor recovery following spinal cord injury (SCI). The purpose of this study was to assess behavioral recovery following SCI with three tasks: (1) BBB ratings, (2) walking on a horizontal ladder, and (3) footprint analyses. Behavioral testing was conducted for 6 postoperative weeks, and then the spinal cords were processed for the amount of white matter spared. As expected, BBB ratings dramatically decreased and then improved during recovery. The number of hindlimb foot-faults on the horizontal ladder increased after injury and remained elevated during the recovery period. Footprint analyses revealed that sham-control rats used several different gaits to cross the runway. In contrast, the locomotor function of rats with a SCI was impaired throughout the postoperative period. Some locomotor parameters of the injured rats improved slightly (velocity, stride length, stride duration, stance duration), some did not change (interlimb coordination, swing duration, forelimb base of support, hindpaw angle), and others declined (hindlimb base of support) during the recovery period. Together, these results show that gross locomotor skill improved after SCI, while recovery of fine locomotor function was more limited. Multiple tests should be included in future experiments in order to assess gross and fine changes in sensorimotor function following SCI.

Animals↗

PubMed2002

Locomotor activity in spinal man: significance of afferent input from joint and load receptors.

The aim of this study was to differentiate the effects of body load and joint movements on the leg muscle activation pattern during assisted locomotion in spinal man. Stepping movements were induced by a driven gait orthosis (DGO) on a treadmill in patients with complete para-/tetraplegia and, for comparison, in healthy subjects. All subjects were unloaded by 70% of their body weight. EMG of upper and lower leg muscles and joint movements of the DGO of both legs were recorded. In the patients, normal stepping movements and those mainly restricted to the hips (blocked knees) were associated with a pattern of leg muscle EMG activity that corresponded to that of the healthy subjects, but the amplitude was smaller. Locomotor movements restricted to imposed ankle joint movements were followed by no, or only focal EMG responses in the stretched muscles. Unilateral locomotion in the patients was associated with a normal pattern of leg muscle EMG activity restricted to the moving side, while in the healthy subjects a bilateral activation occurred. This indicates that interlimb coordination depends on a supraspinal input. During locomotion with 100% body unloading in healthy subjects and patients, no EMG activity was present. Thus, it can be concluded that afferent input from hip joints, in combination with that from load receptors, plays a crucial role in the generation of locomotor activity in the isolated human spinal cord. This is in line with observations from infant stepping experiments and experiments in cats. Afferent feedback from knee and ankle joints may be involved largely in the control of focal movements.

Adult↗

PubMed1995

Developmental shifts in the ability of infants with Down syndrome to produce treadmill steps.

BACKGROUND AND PURPOSE: In this study, we used a dynamic systems strategy to examine longitudinally the ability of infants with Down syndrome to produce alternating steps when supported on a motorized treadmill. SUBJECTS: Seven infants participated, ranging in age from 8 to 11 months at entry into the study and 13 to 29 months at their final session. METHODS: Data were collected in the infants' homes on a monthly basis. Testing continued until each subject produced consistent alternating step patterns during three consecutive test sessions. RESULTS: All infants responded by producing alternating steps, on average, 13.3 months before they walked independently, but they initiated this response at a wide range of chronological ages and significantly later than reported previously for nondisabled infants. Similar developmental variables (control parameters) marked the shift into responsiveness to the treadmill context for all infants with Down syndrome, but these variables differed from those identified for nondisabled infants. CONCLUSION AND DISCUSSION: With age, alternating treadmill stepping became a more stable response, although the relative timing of interlimb coordination (phase lag) of the step cycles remained quite variable across ages. We discuss our results relative to the usefulness of dynamic systems theory in understanding delayed development and the possibilities of pursuing the treadmill paradigm as an intervention approach.

Down Syndrome↗

PubMed1999

The influence of different exercise regimens on the development of locomotion in the foal.

To study the influence of different exercise regimens on the development of locomotion, 40 Warmblood foals aged 1 week were subdivided into 3 groups: box-rest, training and pasture exercise. The box-rest group remained for 24 h a day in a box stall while the training group was housed similarly, but additionally received a 30 min workout with gallop sprints 6 times a week. The pasture group served as a control group and was kept at pasture for 24 h a day. After 5 months, the locomotion pattern at the trot of every foal was recorded overground with a 2-D MacReflex gait analysis system. A randomly selected group of 19 foals was recorded again at age 11 months after they had been kept in an open loose box with access to a small paddock without any specific training for 6 months duration. At 5 months of age the box-rest group moved with a more protracted forelimb, and more extended shoulder and elbow joints than the pasture group. Carpal and fetlock joint kinematics were rather similar in all groups. In the hindlimb, the box-rest foals were significantly different from the other 2 groups, reflected in a more retracted hindlimb, more hip extension, more flexed stifle and tarsal joints, and a larger maximal flexion of hip, stifle, tarsal and fetlock joints. In the simultaneous video recordings this locomotion pattern was visible as a hypermetric movement. The larger protraction in the forelimb and retraction in the hindlimb, as seen in the box-rest group, is opposite to the interlimb coordination of a superior moving horse. The pastured foals had a smaller range of motion of the shoulder and hip joint and less maximal step height of both fore and hind hooves, while the velocity and step length were similar between the 3 groups. Pastured foals could trot the same distance with less joint motion and therefore had a more efficient intralimb coordination. The training group moved in a way comparable with the box-rest group in the similar velocity box-rest foals trot with an abnormal, hypermetric and therefore inefficient and poorer locomotion pattern. When, superimposed on box-rest, exercise is provided in the form of gallop sprints, this will mainly improve the hindlimb locomotion. These induced differences in locomotion pattern of foals can be reversed when the foals afterwards are subjected to the same exercise regimen again.

Animals↗

PubMed2005

Functional differentiation and organization of feline midlumbar commissural interneurones.

Interneurones interconnecting the two sides of the spinal cord (commissural interneurones) are critically important for interlimb coordination, but little is known about their organization. We have examined the inputs to commissural interneurones located in the midlumbar segments with projections to contralateral motor nuclei, aiming to determine whether they form distinct subpopulations. Based on intracellular records from 78 interneurones, two major non-overlapping subpopulations were identified: one monosynaptically excited by group II muscle afferents (n=10), the other monosynaptically excited by reticulospinal neurones (n=52). Monosynaptic input from group I muscle afferents and/or from vestibulospinal tract neurones was found in those with monosynaptic reticulospinal, but not group II input, and in a few other neurones (n=6). Only disynaptic input from these sources was found in the remaining 10 interneurones. Disynaptic excitatory input from ipsilateral and contralateral muscle afferents and from descending tracts was distributed less selectively and might mediate coexcitation of interneurones with monosynaptic afferent or descending input. The dominant disynaptic and polysynaptic input was, however, inhibitory. IPSPs were evoked from the descending tracts in a high proportion of the commissural interneurones that were monosynaptically excited by group II afferents (55%) and from group II afferents in a high proportion of the commissural interneurones that were monosynaptically excited by reticulospinal fibres (78%). This distribution suggests that the two subpopulations are activated differentially, rather than being coactivated, in either centrally initiated movements or reflex adjustments. This would be consistent with the previous demonstration that noradrenaline differentially affects commissural neurones of the two subpopulations.

Animals↗

PubMed2002

Discharge characteristics of neurons in the red nucleus during voluntary gait modifications: a comparison with the motor cortex.

We have examined the contribution of the red nucleus to the control of locomotion in the cat. Neuronal activity was recorded from 157 rubral neurons, including identified rubrospinal neurons, in three cats trained to walk on a treadmill and to step over obstacles attached to the moving belt. Of 72 neurons with a receptive field confined to the contralateral forelimb, 66 were phasically active during unobstructed locomotion. The maximal activity of the majority of neurons (59/66) was centered around the swing phase of locomotion. Slightly more than half of the neurons (36/66) were phasically activity during both swing and stance. In addition, some rubral neurons (14/66) showed multiple periods of phasic activity within the swing phase of the locomotor cycle. Periods of phasic discharge temporally coincident with the swing phase of the ipsilateral limb were observed in 7/66 neurons. During voluntary gait modifications, most forelimb-related neurons (70/72) showed a significant increase in their discharge activity when the contralateral limb was the first to step over the obstacle (lead condition). Maximal activity in nearly all cells (63/70) was observed during the swing phase, and 23/63 rubral neurons exhibited multiple increases of activity during the modified swing phase. A number of cells (18/70) showed multiple periods of increased activity during swing and stance. Many of the neurons (35/63, 56%) showed an increase in activity at the end of the swing phase; this period of activity was temporally coincident with the period of activity in wrist dorsiflexors, such as the extensor digitorum communis. A smaller proportion of neurons with receptive fields restricted to the hindlimbs showed similar characteristics to those observed in the population of forelimb-related neurons. The overall characteristics of these rubral neurons are similar to those that we obtained previously from pyramidal tract neurons recorded from the motor cortex during an identical task. However, in contrast to the results obtained in the rubral neurons, most motor cortical neurons showed only one period of increased activity during the step cycle. We suggest that both structures contribute to the modifications of the pattern of EMG activity that are required to produce the change in limb trajectory needed to step over an obstacle. However, the results suggest an additional role for the red nucleus in regulating intra- and interlimb coordination.

Action Potentials↗

PubMed2002

Patterns of bimanual interference reveal movement encoding within a radial egocentric reference frame.

Constraints on interlimb coordination have been studied intensively in past years with a primary focus on temporal features. The present study addressed spatial constraints or the degree of directional interference as a function of different line combinations between the upper limbs as well as the modulation of this interference as a result of different board orientations within the performer's workspace. This paradigm was used to address a prominent theme in motor neuroscience, namely whether (bimanual) movements are encoded within an allocentric reference frame (pattern of interference invariant with respect to extrinsic space) or within an egocentric reference frame (pattern of interference invariant relative to the center of the performer's action space, i.e., intrinsic). The observed patterns of interference revealed that movements are primarily encoded within a radial egocentric reference frame in which the performer is the center of action space. The present psychophysical findings converge with primate single-cell recording studies in which the direction has been identified as a primary movement parameter that is encoded in various brain regions, thereby constituting a principal determinant of bilateral interference.

Adult↗

PubMed2002

Instrumented treadmill for measuring vertical ground reaction forces in horses.

OBJECTIVE: To develop and validate a novel instrumented treadmill capable of determining vertical ground reaction forces of all 4 limbs simultaneously in horses. SAMPLE POPULATION: Data obtained while a horse was walking and trotting on the treadmill. PROCEDURE: 18 piezo-electric force transducers were mounted between the treadmill frame and supporting steel platform to measure the actual forces at the corresponding bearing points. Each of the 18 sensor forces is equal to the sum of the unknown hoof forces weighted with the transfer coefficients of the corresponding force application points. The 4 force traces were calculated, solving at each time point the resulting equation system, using the Gaussian least-squares method. System validation comprised the following tests: determination of the survey accuracy of the positioning system, determination of the natural frequencies of the system, linearity test of the force transfer to the individual sensors, determination of superimposed forces with the treadmill-integrated force measuring system (TiF) in a static configuration, and comparison of vertical ground reaction forces determined simultaneously by use of TiF and force shoes mounted on the forelimbs of a horse. RESULTS: Comparison between static test loads and TiF-calculated forces revealed deviations of < 1.4%. Force traces of TiF-calculated values and those recorded by use of the force shoes were highly correlated (r > or = 0.998). CONCLUSIONS AND CLINICAL RELEVANCE: This instrumented treadmill allows a reliable assessment of load distribution and interlimb coordination in a short period and, therefore, is suitable for use in experimental and clinical investigations.

Animals↗

PubMed2006

Locomotor mechanics of the tölt in Icelandic horses.

OBJECTIVE: To evaluate the locomotor mechanics of the tölt in Icelandic horses. ANIMALS: 10 adult Icelandic horses with no history of lameness. PROCEDURES: Force platform data were captured for 27 trials for horses ridden at a tölt in a lateral sequence single-foot gait at a steady speed from 0.89 to 5.98 m/s. Simultaneous kinematic data were obtained by tracking retroflective markers overlying the right fore- and hind limbs. These kinetic and kinematic data were combined to evaluate 3 mechanical approaches, duty factor, Froude number, and center of mass (COM) mechanics, and to evaluate the capacity to recover mechanical energies during tölting via inverse pendulum and spring-mass (bouncing) mechanics. RESULTS: Tölting horses had in-phase fluctuations of gravitational potential and kinetic energies of their COM and a capacity to recover mechanical energy through elastic recoil of spring elements in their limbs. These characteristics, along with Froude numbers exceeding values expected for the walk-run transition, are indicative of bouncing mechanics and, hence, most strongly ally tölting with running. Only the footfall pattern of a lateral sequence single-foot gait and low vertical excursions of the COM are more commonly associated with walking. CONCLUSIONS AND CLINICAL RELEVANCE: At the tölt, horses have unique mechanical characteristics that should be understood for veterinary care. Differences in interlimb coordination between tölting and trotting mask the overall similarities in most other aspects of their locomotor dynamics.

Animals↗

PubMed2004

Variability in head movement during gait transitions.

Predictions from a model of coupled oscillators, which was based on stationary interlimb coordination, were examined in locomotor intralimb coordination. The present study measured head linear and angular accelerations and coordination relationships of the head and torso, e.g., using relative phase measures, during walking and running on a treadmill. Head linear acceleration increased from walking to running and decreased from running to walking, and head pitch/torso pitch relative phase decreased from walking to running and increased from running to walking. No other measures were significantly different for either walking or running (head angular acceleration, mean head vertical displacement/head pitch relative phase, SD head vertical displacement/head pitch, and SD head pitch/torso pitch). This information will aid further understanding of the many aspects involved in locomotor coordination.

Adult↗

PubMed1995

Effects of unilateral somatosensory cortex lesion upon locomotion in dogs.

Locomotive limb movements were studied in 6 dogs before and after unilateral (right) primary somatosensory cortex (SI) lesion. Single limb movement parameters as well as interlimb coordination in lesioned dogs differed significantly from the parameters measured before surgery. Both left limbs showed a proprioceptive deficit and were more flexed during normal posture and during locomotion. This resulted in prolonged stance in the left fore and in the right hind legs. The symptoms were greatly pronounced in the left fore limb compared to a slightly impaired left hindlimb. Due to the proprioceptive deficit, the dogs did not have satisfactory control over the position of the distal part of the front limb which caused frequent stumbling and even falling. The symptoms were transient and fully compensated after 3-4 weeks.

Analysis of Variance↗

PubMed1997

Bilateral projection of neurones of the C6 segment to S1 and S2 segments of the spinal cord in the cat.

Sacral projections of neurones located in the C6 segment of the spinal cord were electrophysiologically investigated in alpha-chloralose anaesthetized cats. The cell bodies were found mainly in lamina VIII and in the ventromedial part of lamina VII of the C6 segment. At the thoracic level their axons descended in lateral funiculi, mostly on both sides and only exceptionally contra- or ipsilaterally. However, bilateral projection to sacral segments was less frequent (25 neurones). It is concluded that axons terminate at different levels on both sides of the spinal cord and only part of them project bilaterally to S1/S2 segments. Conduction velocities calculated for all the axons varied from 38 to 80 m/s and were significantly slower for their distal parts. Therefore it is suggested that descending axons send collaterals at various spinal levels. The presented data indicate the importance of these neurones for interlimb coordination.

Animals↗