DESCENDING TRACTS AND SPINAL SHOCK IN THE MONKEY (Macaca mulatta)

Impairment of voluntary control of finger motion following stroke: Role of inappropriate muscle coactivation

“…Neural reorganization can also occur at the segmental level in the spinal cord. Axonal sprouting may take place to fill some of the gaps left by the degeneration of descending axons 25. This sprouting would alter the organization of segmental pathways, possibly including those coordinating activity between the agonist and antagonist.…”

Recovery of neuronal and network excitability after spinal cord injury and implications for spasticity

“…The duration and severity of spinal shock differs between species, lasting only minutes to hours in the frog (Hall, 1850), cat (Sherrington, 1899; Hunt et al, 1963; Chambers et al, 1966) and dog (Sherrington, 1899; Fulton and Sherrington, 1932) but up to 2 weeks in the monkey (Sherrington, 1899; Fulton and Sherrington, 1932; Hunt et al, 1963; McCouch et al, 1966), rat (Bennett et al, 1999) and several weeks in humans (Ko et al, 1999). In humans, all reflexes are absent only for the first 24 h after SCI (Phase 1) (Ditunno et al, 2004), which coincides with the first 2 weeks of areflexia in the rat tail model of SCI (Bennett et al, 1999).…”

Anatomical and Physiological Correlates of Plasticity in the Central Nervous System

“…In the monkey, the reflex picture is overwhelmed by spinal shock [5]. The only reflexes permanently retained are tremulous quivering of digits and in some cases adductor and knee jerks [5,21,28]. A number of other reflexes may persist for 1 or 2 h, fade out, and return only after several days [30].…”

“…If the monkey's cord be acutely transected after a chronic unilateral lesion of the motor cortex, the subsequent reflex depression is less on the previously paretic side, which recovered during the interoperative period from the moiety of shock due to pyramidal loss, than on the previously normal side that suffered loss of all its descending tracts at one blow [24]. Such asymmetry is greater in the green monkey than in the erythrocebus, greater in the macaque or the baboon than in the green, and far greater in the chimpanzee than in any of the lower forms [10], A more detailed study of spinal macaque monkeys with previous chronic unilateral lesions of various descending tracts provided an estimate of the relative impor tance of each in the maintenance of normal reflex activity [28], Thus, hemisection of cord and section of one pyramid each induced prolonged asymmetry throughout the lower limbs, the inequality slightly greater af ter the former lesion. Total area 4 damage gave greater asymmetry in dis tal than in proximal segments.…”

“…To these should be added release from inhibition from higher cen ters. To such escape we are inclined to attribute the early appearance of digital quivering in response to pinch, a reflex which does not occur in the normal animal [21,28,30].…”