Stabilization of cat paw trajectory during locomotion

Abstract

We investigated which of cat limb kinematic variables during swing of regular walking and accurate stepping along a horizontal ladder are stabilized by coordinated changes of limb segment angles. Three hypotheses were tested: 1) animals stabilize the entire swing trajectory of specific kinematic variables (performance variables); and 2) the level of trajectory stabilization is similar between regular and ladder walking and 3) is higher for forelimbs compared with hindlimbs. We used the framework of the uncontrolled manifold (UCM) hypothesis to quantify the structure of variance of limb kinematics in the limb segment orientation space across steps. Two components of variance were quantified for each potential performance variable, one of which affected it ("bad variance," variance orthogonal to the UCM, VORT) while the other one did not ("good variance," variance within the UCM, VUCM). The analysis of five candidate performance variables revealed that cats during both locomotor behaviors stabilize 1) paw vertical position during the entire swing (VUCM > VORT, except in mid-hindpaw swing of ladder walking) and 2) horizontal paw position in initial and terminal swing (except for the entire forepaw swing of regular walking). We also found that the limb length was typically stabilized in midswing, whereas limb orientation was not (VUCM ≤ VORT) for both limbs and behaviors during entire swing. We conclude that stabilization of paw position in early and terminal swing enables accurate and stable locomotion, while stabilization of vertical paw position in midswing helps paw clearance. This study is the first to demonstrate the applicability of the UCM-based analysis to nonhuman movement.

The spinal control of locomotion and step-to-step variability in left-right symmetry from slow to moderate speeds

“…6). As others have proposed (Hollands and Marple-Horvat 1996;Klishko et al 2014;Patla and Vickers 2003) and based on our results, it is likely that paw placement at contact is planned before swing onset. Initial position of the paw at swing onset does not appear to be a factor in determining paw placement at contact because the transition from stance to swing occurred with the paw positioned more caudally with increasing speed (Fig.…”

“…The position of the paw at contact is arguably the most important event in the step cycle because it is critical to maintain dynamic stability (Halbertsma 1983;Klishko et al 2014). Here we show that placement of the hind paw relative to the hip at contact in chronic spinalized adult cats is invariant across speeds for both the left and right sides (Fig.…”

“…It is possible that spatial adjustments to speed, such as increases in stride length and step length with increasing speed, observed in intact quadrupeds (Afelt et al 1983;Blaszczyk and Dobrzecka 1989;Frigon et al 2014;Thibaudier and Frigon 2014) are mainly controlled at a spinal level. The placement of the paw at contact, an important event in the cycle that ensures a stable base of support (Halbertsma 1983;Klishko et al 2014), could also be controlled primarily at a spinal level.…”

Neural control of movement stability: Lessons from studies of neurological patients

“…The task is formed at cortical levels while the few-to-many mappings rely significantly on subcortical structures. These may involve the spinal cord as suggested by recent observations of multi-joint synergies stabilizing paw trajectory during locomotion of intact cats and induced locomotion in spinalized cats (Klishko et al, 2014a,b). Future systematic studies of the neural control of movement stability in animal models, healthy humans, and different neurological disorders may help us to understand the neural substrates of ICS, assist the lesion localization, and development of treatment strategies.…”

Flexor Dysfunction Following Unilateral Transient Ischemic Brain Injury Is Associated with Impaired Locomotor Rhythmicity

“…This find is in line with the present literature on the topic. Namely, over the course of the last 30 years, the work of Irina Beloozerova and her lab has demonstrated that higher centers of motor control, such as the motor cortex and basal ganglia, are most implicated in task that require precise limb manipulations during locomotion 235,236,249,250 . Furthermore, studies by Trevor Drew et al have also demonstrated that the dorsiflexor related function during the production of obstacle avoidance trajectories is most significantly impaired following the GABA-receptor agonist muscimol injections to the motor cortex in the cat 221 , which is a comparable manipulation to that of transient ischemic ablation of the motor cortex.…”