Locomotor Control in Macaque Monkeys

Abstract

We carried out experiments on young adult macaque monkeys (M.fascicularis) in an attempt to establish whether or not primates possess a locomotor control system consisting of spinal pattern generators modulated by brain-stem locomotor regions. We could not induce 'spinal stepping' in our subjects after spinal cord transection. Sparing of pathways contained in the central sector of the white matter of the cord was sufficient for stepping and walking. 'Controlled locomotion' was elicited in thalamic monkeys by electrical stimulation of the posterior subthalamic region or the midbrain tegmentum just ventral to the inferior colliculi. We conclude that there are significant homologies between this primate species and the cat regarding the probable existence of supraspinal locomotor control structures, but it seems that the presumed spinal step generators in monkeys depend more on supraspinal inputs than they do in cats.

Weak motor cortex contribution to the quadriceps activity during human walking

“…Similar spinal organisations have been suggested in primates, but their activation under experimental conditions is more difficult than in other animal species, suggesting a stronger supraspinal control onto the presumed spinal step generators in primates [16,17]. Besides clinical observations in patients with spinal cord injury or cortical lesion, experimental data obtained in neurologically intact subjects further support the crucial role of motor cortex in human locomotion [6,9,18].…”

The pedunculopontine nucleus in Parkinson's disease: primate studies

“…This has been demonstrated on a treadmill in decerebrate models of the cat 14 the rat, 15 and also to some extent, in the primate. 16 It has been shown, in anaesthetized rats, that tonic activity is recorded from nearly three quarters of the neurons (type 2) in the PPN and bursting patterns are seen in a quarter (type 1). 17 It has been postulated that the tonic neurons control the duration of the stepping movements, while the bursting neurons modulate the frequency.…”

Neurologic disorders of gait

“…Eidelberg et al [9] have demonstrated a form of patterned locomotion with stimulation of the mesencephalic locomotor region, an area near the nucleus cuneifomis below the superior cerebellar peduncle. This area includes the pedunculopontine nucleus (PPN), which is a good candidate for a locomotor center.…”