Effect of pairing red nucleus and motor thalamic lesions on reaching toward moving targets in cats.

Abstract

The small effects of bilateral lesions of motor thalamus on motor control and the transient deficits induced by bilateral kainic red nucleus (RN) lesions have been explained by a parallel competitive role of the cortico- and rubro-spinal pathways. Either pathway can take over motor control if the other is damaged. In this study the effect of bilateral and simultaneous lesions of both RN and motor thalamus was analyzed on cats overtrained to reach toward a moving target. After lesion, accuracy was impaired, movement onset was delayed, and movement execution was perturbed. However, postoperative retraining led to full recovery of the preoperative accuracy level although movement latency remained higher. The relative mildness of the long-lasting deficit after lesioning 2 main motor brain structures underlines the robustness of overlearned movements and widens the idea of parallelism in the motor system to other (subcortical?) pathways.

Enhanced Behavioral Recovery from Sensorimotor Cortex Lesions After Pyramidotomy in Adult Rats

“…Cerebellar messages can modulate the activity of these tracts through both the motor cortex and the red nucleus. In the cat, cerebellar outputs gain access to the various cortical zones through the ventrolateral and the ventroanterior thalamic nuclei (motor thalamus) (Lorincz & Fabre-Thorpe, 1997). The cerebellum can also influence the rubrospinal and rubroolivary tracts through its direct projections onto the red nucleus (Massion 1967;Fanardjian & Sarkisian, 1992).…”

“…As the movements were learned, their execution become automated under the control of the rubrospinal tract. Supposedly, such a switching function of the rubro-olivary projection acts in both directions; i.e., it can switch from the eortieospinal tract to the rubrospinal tract and from the rubrospinal tract to the eortieospinal tract (Lorinez & Fabre-Thorpe, 1997). In eats and rats, lesion studies confirm a considerable duplication between the rubrospinal tract and the eortieospinal Cerebral Cortex """'"'.c7 .... 7 s "/' C o r t e x C e r e b e I I a r cs Fig.…”

“…Such facilitation is considered to be the result of a switching of motor activity onto the corticospinal system by the activation of rubroolivary projections (Kennedy, 1990). Supposedly, the switching effect of the latter is executed in both directions, from the corticospinal system onto the rubrospinal system or vice versa (Lorincz & Fabre-Thorpe, 1997). This model of correlation between the bulbar pyramid and the sensorimotor cortex appears to be analogous with the previously investigated model, rubrospinal tract-red nucleus (Fanardjian et al, 2000).…”

Longitudinal assessment of gait abnormalities following penetrating ballistic-like brain injury in rats

“…As has been demonstrated in lesion studies conducted in cats and rats, there is considerable duplication between the rubrospinal and corticospinal tract. A deficit produced in one of the two systems is just transitory (Lorincz and Fabre-Thorpe, 1997), and the functional recovery occurs due to compensation from the undamaged system (Fanardjian et al, 2000).…”