scholarly journals Comparison of the Effects of Electrolytic and Chemical Destruction of the Red Nucleus on the Compensatory Capacity of Rats With Rubrospinal Tract Lesions

1999 ◽  
Vol 6 (4) ◽  
pp. 123-131 ◽  
Author(s):  
V. V. Fanardjian ◽  
E. V. Papoyan ◽  
V. I. Pogossian ◽  
O. V. Gevorkyan
Keyword(s):  
Thalamic Nucleus ◽  
Inferior Olive ◽  
Red Nucleus ◽  
Recovery Process ◽  
Rubrospinal Tract ◽  
Switching Phenomenon ◽  
Chemical Destruction ◽  
Descending Influences ◽  
Switching Of Descending Influences ◽  
Ventrolateral Thalamic Nucleus

Transection of the rubrospinal tract in rats, performed before lesion of the red nucleus, resulted in the facilitated recovery of motor activity and operantly conditioned reflexes. Such facilitation was absent when the red nucleus is lesioned alone. This phenomenon is explained by the switching of descending influences on the corticospinal tract through the participation of the following system: red nucleus—inferior olive—cerebellum—ventrolateral thalamic nucleus—cerebral cortex. The above mentioned facilitating influence on the recovery process was particularly prominent in rats with quinolinic acid-induced lesion of the red nucleus. Under these conditions, the cerebellar ascending fibers to the ventrolateral thalamic nucleus were preserved. Decreased facilitated recovery following electrolytic lesion of the red nucleus suggests the existence of additional cerebello-cortical pathways for the realization of the switching phenomenon.

Inhibition of sensory responses of cat inferior olive neurons produced by stimulation of red nucleus

1990 ◽  
Vol 64 (4) ◽  
pp. 1170-1185 ◽  
Author(s):  
C. Weiss ◽  
J. C. Houk ◽  
A. R. Gibson
Keyword(s):  
Time Course ◽  
Inferior Olive ◽  
Red Nucleus ◽  
Active Movement ◽  
Rubrospinal Tract ◽  
Sensory Responsiveness ◽  
Train Duration ◽  
Sensory Responses ◽  
Mean Current ◽  
Stimulation Of

1. The sensory responsiveness of cells in the inferior olive is known to be suppressed during certain phases of active movement. These experiments were designed to test the possibility that activity in the rubrospinal pathway contributes to this suppression. We recorded from cells sensitive to light touch located in one of the divisions of the inferior olive, the rostral dorsal accessory olive (rDAO), in cats anesthetized with pentobarbitol sodium. Responsiveness to peripheral stimuli was tested during and after trains of conditioning stimuli delivered to the rubrospinal pathway. 2. All 44 cells in our sample of rDAO neurons showed an inhibition of responsiveness to peripheral stimuli after conditioning stimulation of the rubrospinal pathway. Typical conditioning trains consisted of 0.2-ms pulses at 200 Hz for 100 ms. The mean current required for a reduction in firing probability to 0.5 was 31 microA. Slight increases in intensity often completely inhibited responses to peripheral stimuli. 3. Inhibition of responsiveness showed a delayed time course. Peak inhibition occurred approximately 50 ms after the last pulse in the conditioning train. In many cases there was no demonstrable inhibition during the conditioning train. Increases of train frequency, train duration, or stimulus intensity produced stronger and broader periods of olivary inhibition. 4. The lowest threshold points for eliciting rDAO inhibition coincided with either the magnocellular red nucleus (RNm) or the rubrospinal tract (RST). Stimulation at RST sites produced inhibition of responses in the contralateral but not in the ipsilateral rDAO. Transection of the RST in the upper brain stem blocked the inhibition produced by red-nucleus stimulation without altering the inhibition produced by tract stimulation caudal to the transection. The inhibitory effects thus appear to be caused by activation of the rubrospinal pathway. 5. The inhibitory timing observed in this study may be appropriate for explaining the suppression of olivary responsiveness to contact that has been observed in awake animals. Bursts of movement-related, red nucleus discharge often cease approximately 50 ms before the end of movement. This timing would allow peak inhibition to develop at approximately the time of contact with an object at the end of a goal-directed limb movement.

Somatotopic studies on red nucleus: spinal projection level and respective receptive fields

1975 ◽  
Vol 38 (4) ◽  
pp. 965-980 ◽  
Author(s):  
J. C. Eccles ◽  
T. Rantucci ◽  
P. Scheid ◽  
H. Taborikova
Keyword(s):  
Spinal Cord ◽  
Red Nucleus ◽  
Receptive Fields ◽  
Anterior Lobe ◽  
Cervical Cord ◽  
Pars Intermedia ◽  
Interpositus Nucleus ◽  
Rubrospinal Tract ◽  
Testing Procedures ◽  
Axonal Projections

The somatotopic inputs into red nucleus (RN) neurons have been studied with special reference to their level of projection in the spinal cord. As inputs we employed either volleys in predominantly cutaneous nerves of forelimb and hindlimb or cutaneous mechanoreceptor discharges evoked by taps to footpads of forelimb and hindlimb. There has been physiological confirmation of the anatomical findings that RD neurons projecting to the lumbar cord are located in the ventrolateral zone of the pars magnocellularis, whereas in the dorsomedial zone are RN neurons with cervical but not lumbar projection. Somatotopically there was found to be a differentiation of input to RN neurons according as they projected to the lumbar or only to the cervical cord. This finding was presented in the form both of tables and of somatotopic maps. As expected, this discrimination was more restrictive for the more selective inputs from pad taps than for nerve inputs. Nevertheless, forelimb inputs often had a considerable excitatory and inhibitory action on lumbar-projecting RN neurons, and vice versa for cervical-projecting neurons. There were two notable somatotopic findings that suggest specificities of connectivities. First, despite the large convergence of IP neurons onto RN neurons (about 50-fold), the degree of somatotopic discrimination was about the same for interpositus and RN neurons with two testing procedures: between inputs from forelimb and hindlimb; and between inputs from pads on one foot. Second, although there was in the interpositus nucleus a considerable topographical admixture of neurons with dominant forelimb or hindlimb inputs, the axonal projections of these neurons were apparently unscrambled on the way to the target RN neurons, so as to deliver the somatotopic specificities observed for two classes of RN neurons; those projecting down the spinal cord beyond L2 level, and those projecting to C2 but not L2. Finally, there is a general discussion of motor control with reference to the pathway; pars intermedia of anterior lobe of cerebellum leads to interpositus nucleus leads to red nucleus leads to rubrospinal tract leads to spinal motoneurons.

Red Nucleus Stimulation Inhibits Within the Inferior Olive

1998 ◽  
Vol 80 (6) ◽  
pp. 3127-3136 ◽  
Author(s):  
K. M. Horn ◽  
T. M. Hamm ◽  
A. R. Gibson
Keyword(s):  
Inferior Olive ◽  
Red Nucleus ◽  
Salient Feature ◽  
Cutaneous Stimulation ◽  
Motor Pathways ◽  
Peripheral Stimulation ◽  
Dorsal Columns ◽  
Dorsolateral Funiculus ◽  
Somatosensory Responses ◽  
Stimulation Of

Horn, K. M., T. M. Hamm, and A. R. Gibson. Red nucleus stimulation inhibits within the inferior olive. J. Neurophysiol. 80: 3127–3136, 1998. In the anesthetized cat, electrical stimulation of the magnocellular red nucleus (RNm) inhibits responses of rostral dorsal accessory olive (rDAO) neurons to cutaneous stimulation. We tested the hypothesis that RNm-mediated inhibition occurs within the inferior olive by using stimulation of the ventral funiculus (VF) of the spinal cord in place of cutaneous stimulation of the hindlimb. Fibers in the VF terminate on hindlimb rDAO neurons, so inhibition of this input would have to occur within the olive. rDAO responses elicited by VF stimulation were inhibited by prior stimulation of the RNm, indicating that inhibition occurs within the olive. In contrast, evoked potentials recorded from the VF or dorsal columns following hindlimb stimulation were not affected by prior stimulation of RNm, indicating that stimulation of the RNm does not inhibit olivary afferents at spinal levels. RNm stimulation that inhibited rDAO responses had little effect on evoked somatosensory responses in thalamus, indicating that inhibition generated by activity in RNm may be specific to rDAO. To test limb specificity of RNm-mediated inhibition, conditioning stimulation was applied to the dorsolateral funiculus at thoracic levels, which selectively activates RNm neurons projecting to the lumbar cord. Stimulation at thoracic levels inhibited evoked responses from hindlimb but not forelimb regions of rDAO, suggesting that inhibitory effects of RNm activity are limb specific. Several studies have reported that olivary neurons have reduced sensitivity to peripheral stimulation during movement; it is likely that RNm-mediated inhibition occurring within the olive contributes to this reduction of sensitivity. Inhibition of rDAO responses by descending motor pathways appears to be a salient feature of olivary function.

Sign in / Sign up

Export Citation Format

Share Document