Kinematics of locomotion by cats with a single hindlimb deafferented

Abstract

1. Cinematographic measurements were made of stepping by cats on a motor-driven treadmill, both normally and 2-3 wk after deafferentation of the LH (left hind) limb. 2. After surgery, rhythmic cycling of the LH limb was blurred whether the leg was dragged, as by some cats, or if it was lifted from the surface, as by others. 3. Interlimb coordination was also blurred with respect to normal, although distinct rhythms were still seen. The RH (right hind) limb descended prematurely and, in the walk, had a prolonged stance phase. The interval between touchdowns of hind- and forelimb on the left side no longer equaled that interval on the right side. 4. As is true for a normal cat, if the LH-deafferented animal stumbled, relatively normal single and interlimb cyclings were regained after several strides. 5. By kinematic analysis, force deficits were found in the deafferented LH limb both during the stance, when extensors should be most active, and the swing, when the limb failed to attain a normal position above the surface of the belt. Weight bearing by the LF (left fore) limb was altered in some animals. 6. At high speed, mean LH stance duration failed to decrease in the normal fashion. Inter-limb timings were reset to greater extent than in low-speed walking, as if the LH limb was being used only minimally. 7. It was concluded that both rhythm and force were impaired in the deafferented limb and also in the three intact limbs, whose weight bearing had to compensate for LH weakness. The changed mechanical demands after surgery were probably met by interactions between the remaining afferent input and central pattern generators so as to secure fairly effective and expedient locomotion.

Control of LocomotionIn Vitro: I. Deafferentation

“…Early studies using deaerentation of one limb described more feeble movements in the deafferented limb than in the other limbs (Wetzel et al, 1976). More recently, such preparations were found to be capable of weight support, but occasional decreases in movement and EMG amplitude were observed (Grillner and Zangger, 1984).…”

Force encoding in stick insect legs delineates a reference frame for motor control

“…Many insects maintain adhesion by generating forces along the long axis of the leg (Niederegger and Gorb 2003). During walking on vertical or inverted surfaces, the legs are used in a strategy known as distributed inward grip, in which the long axes of opposite legs are aligned across the body to maintain substrate contact (Wile et al 2008). By positioning pairs of legs in opposition, each leg can develop axial forces that effectively counter the forces from the opposite leg.…”

“…Earlier experiments demonstrated that the trochanteral receptors are particularly important in walking. After removal of the trochanter sensors (by amputation or cutting of leg nerves), animals do not use the leg forcefully and show multiple stepping in single cycles of movement (Noah et al 2004;Wendler 1966), similar to findings in cats in which individual legs were deafferented by dorsal rhizotomy (Wetzel et al 1976). Recent studies have also shown that trochanteral campaniform sensilla have potent effects on pattern generation in walking: sensory signals can reset the rhythm of muscle bursts (Akay et al 2004) and have determining effects on the pattern of leg coordination (Borgmann et al 2009).…”

Muscle Spindles and Locomotor Control-An Unrecognized Falls Determinant?

“…Although disputed to some degree by findings of Loeb et al [36,37] who studied the activity of muscle afferents during walking in two different muscle groups of the cat in the face of fusimotor blockade, corrective actions while walking on a narrow beam seemed to be accompanied by transient increases in dynamic fusimotor drive [38] . Similarly, Wetzel, Atwater, Wait, and Stuart [39] found that deafferentation of the left hind limb caused a deficit in its normal locomotor rhythm as well its force production. In addition, the intact limbs exhibited the same deficits.…”