A kinematic and kinetic analysis of locomotion during voluntary gait modification in the cat

Abstract

As part of a study to characterize the postural reactions that occur during voluntary gait modification, we examined the kinematic, electromyographic (EMG), and kinetic responses that occurred when cats stepped over an obstacle placed in their path. Analyses of the kinematics as each of the forelimbs stepped over the obstacle showed that changes in joint angles were most pronounced at the elbow of the first (lead) limb, and at the shoulder of the second (trailing) limb. In the hindlimbs, there was a pronounced change in the knee joint angle in both the leading and trailing limbs. Examination of the horizontal and vertical velocities of the tip of the forepaw suggests that the movements can be divided into two phases: one in which the limb is rapidly lifted above and over the obstacle, and a slower one during which the limb is carefully repositioned on the floor. On the basis of the velocity profiles, we suggest that the repositioning of the paw on the support surface is more critically controlled for the forelimb than for the hindlimb. Analysis of the changes in the ground reaction forces in the supporting limbs during these gait modifications showed that there were two major increases in vertical reaction force. One of these occurred as the two forelimbs were straddling the obstacle, the other when the two hindlimbs were straddling it. There was also a net increase in the anteroposterior force that resulted in a small increase in propulsion as the cat stepped over the obstacle. Each change in the vertical ground reaction force was paralleled by a similar change in the amplitude of the EMG recorded from the respective extensor muscles. An analysis of the vertical displacement of the scapula and of the pelvis showed that there was a slight increase in the height of the scapula in the support limb just prior to and during the swing phase of the trailing forelimb, and a more pronounced and progressive change in the height of the pelvis prior to and during the passage of both hindlimbs over the obstacle. We suggest that the increases in vertical ground reaction force raise the height of the body sufficiently to allow, respectively, passage of the trail forelimb and each of the hindlimbs over the obstacle. The results are discussed with respect to both the biomechanical changes underlying these gait modifications and the neuronal mechanisms implicated in their control.

Strategies for the Integration of Posture and Movement During Reaching in the Cat

“…As Massion (1992) has strongly emphasized, these responses are also anticipatory in nature in that they are controlled in a feedforward manner to anticipate the changes produced by the movement. Similar arguments have also been made for the postural responses that accompany modifications of locomotor gait (Lavoie et al 1995;McFadyen and Winter 1991). Following the terminology of Gahéry (1987), we refer to these postural responses in Fig.…”

Kinematic and EMG Determinants in Quadrupedal Locomotion of a Non-Human Primate (Rhesus)

“…Accordingly, speed-related increases in the amplitude of HL joint angle changes and the level of HL muscle activity are larger in Rhesus (present results) than in cats (Halbertsma et al 1976;Jiang and Drew 1996;Rossignol 1996), particularly in the distal extremities. In the same vein, vertical reaction forces are larger on the FL than the HL during cat locomotion (Manter 1938;Lavoie et al 1995), whereas the inverse ratio characterizes non-human primate stepping (Kimura 1985). Similar to that observed in monkeys, however, the cat HLs provide propelling forces for a longer period than the FLs, and the FLs are used mainly for braking (Lavoie et al 1995).…”

“…In the same vein, vertical reaction forces are larger on the FL than the HL during cat locomotion (Manter 1938;Lavoie et al 1995), whereas the inverse ratio characterizes non-human primate stepping (Kimura 1985). Similar to that observed in monkeys, however, the cat HLs provide propelling forces for a longer period than the FLs, and the FLs are used mainly for braking (Lavoie et al 1995). This substantial contribution of HL muscles to body propulsion in Rhesus at higher speeds is reflected in the dramatic modulation of distal muscle activity, such as the FDL and FHL muscles, which is not observed in cats (Fleshman et al 1984;O'Donovan et al 1982).…”

Ladder Treadmill: A Method to Assess Locomotion in Cats with an Intact or Lesioned Spinal Cord

“…However, we did not investigate systematically the capacity of these animals to walk voluntarily on specific targets or avoid obstacles that require supraspinal visual inputs. Work in cats (Lavoie et al, 1995;Drew et al, 2008;Farrell et al, 2015) and humans (Patla et al, 1991) has shown the critical importance of direct or indirect cortical mechanisms in controlling precision walking; these mechanisms could participate in the recovery of hemisected cats. We thus developed a repetitive locomotor task that requires some precision walking as previously shown by previous work in a different context and for different needs (Amos et al, 1987;Armstrong and Marple-Horvat, 1996).…”