The pyramidal tract in rodents. A study of its relations with the posterior column nuclei, dorsolateral reticular formation of the medulla oblongata, and cervical spinal cord

1966 ◽  
Vol 71 (3) ◽  
pp. 297-363 ◽  
Author(s):  
F. Valverde
Keyword(s):  
Spinal Cord ◽  
Reticular Formation ◽  
Medulla Oblongata ◽  
Pyramidal Tract ◽  
Cervical Spinal Cord ◽  
Posterior Column

scholarly journals Different contributions of primary motor cortex, reticular formation, and spinal cord to fractionated muscle activation

2018 ◽  
Vol 119 (1) ◽  
pp. 235-250 ◽  
Author(s):  
Boubker Zaaimi ◽  
Lauren R. Dean ◽  
Stuart N. Baker
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Reticular Formation ◽  
Upper Limb ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Cervical Spinal Cord ◽  
Motor Output ◽  
Natural Activity ◽  
Limb Muscles

Coordinated movement requires patterned activation of muscles. In this study, we examined differences in selective activation of primate upper limb muscles by cortical and subcortical regions. Five macaque monkeys were trained to perform a reach and grasp task, and electromyogram (EMG) was recorded from 10 to 24 muscles while weak single-pulse stimuli were delivered through microelectrodes inserted in the motor cortex (M1), reticular formation (RF), or cervical spinal cord (SC). Stimulus intensity was adjusted to a level just above threshold. Stimulus-evoked effects were assessed from averages of rectified EMG. M1, RF, and SC activated 1.5 ± 0.9, 1.9 ± 0.8, and 2.5 ± 1.6 muscles per site (means ± SD); only M1 and SC differed significantly. In between recording sessions, natural muscle activity in the home cage was recorded using a miniature data logger. A novel analysis assessed how well natural activity could be reconstructed by stimulus-evoked responses. This provided two measures: normalized vector length L, reflecting how closely aligned natural and stimulus-evoked activity were, and normalized residual R, measuring the fraction of natural activity not reachable using stimulus-evoked patterns. Average values for M1, RF, and SC were L = 119.1 ± 9.6, 105.9 ± 6.2, and 109.3 ± 8.4% and R = 50.3 ± 4.9, 56.4 ± 3.5, and 51.5 ± 4.8%, respectively. RF was significantly different from M1 and SC on both measurements. RF is thus able to generate an approximation to the motor output with less activation than required by M1 and SC, but M1 and SC are more precise in reaching the exact activation pattern required. Cortical, brainstem, and spinal centers likely play distinct roles, as they cooperate to generate voluntary movements. NEW & NOTEWORTHY Brainstem reticular formation, primary motor cortex, and cervical spinal cord intermediate zone can all activate primate upper limb muscles. However, brainstem output is more efficient but less precise in producing natural patterns of motor output than motor cortex or spinal cord. We suggest that gross muscle synergies from the reticular formation are sculpted and refined by motor cortex and spinal circuits to reach the finely fractionated output characteristic of dexterous primate upper limb movements.

scholarly journals Clinically Relevant Levels of 4-Aminopyridine Strengthen Physiological Responses in Intact Motor Circuits in Rats, Especially After Pyramidal Tract Injury

2017 ◽  
Vol 31 (4) ◽  
pp. 387-396 ◽  
Author(s):  
Anil Sindhurakar ◽  
Asht M. Mishra ◽  
Disha Gupta ◽  
Jennifer F. Iaci ◽  
Tom J. Parry ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Stimulation ◽  
Neural Circuits ◽  
Pyramidal Tract ◽  
Cervical Spinal Cord ◽  
Physiological Responses ◽  
Motor Circuits ◽  
Improve Motor Function ◽  
Drug Plasma ◽  
Brain And Spinal Cord

Background. 4-Aminopyridine (4-AP) is a Food and Drug Administration–approved drug to improve motor function in people with multiple sclerosis. Preliminary results suggest the drug may act on intact neural circuits and not just on demyelinated ones. Objective. To determine if 4-AP at clinically relevant levels alters the excitability of intact motor circuits. Methods. In anesthetized rats, electrodes were placed over motor cortex and the dorsal cervical spinal cord for electrical stimulation, and electromyogram electrodes were inserted into biceps muscle to measure responses. The motor responses to brain and spinal cord stimulation were measured before and for 5 hours after 4-AP administration both in uninjured rats and rats with a cut lesion of the pyramidal tract. Blood was collected at the same time as electrophysiology to determine drug plasma concentration with a goal of 20 to 100 ng/mL. Results. We first determined that a bolus infusion of 0.32 mg/kg 4-AP was optimal: it produced on average 61.5 ± 1.8 ng/mL over the 5 hours after infusion. This dose of 4-AP increased responses to spinal cord stimulation by 1.3-fold in uninjured rats and 3-fold in rats with pyramidal tract lesion. Responses to cortical stimulation also increased by 2-fold in uninjured rats and up to 4-fold in the injured. Conclusion. Clinically relevant levels of 4-AP strongly augment physiological responses in intact circuits, an effect that was more robust after partial injury, demonstrating its broad potential in treating central nervous system injuries.

scholarly journals III. An experimental investigation into the arrangement of the excitable fibres of the internal capsule of the bonnet monkey (macacus sinicus)

1890 ◽  
Vol 181 ◽  
pp. 49-88 ◽  
Keyword(s):  
Spinal Cord ◽  
Experimental Investigation ◽  
Medulla Oblongata ◽  
Grey Matter ◽  
Pyramidal Tract ◽  
Internal Capsule ◽  
Bonnet Monkey ◽  
Cortex Cerebri

In the following paper we propose to give the results of a research on which we have been engaged nearly three years, and by which we hoped to elucidate the arrangement of the motor fibres in the internal capsule. The fibres which connect the excitable areas in the cortex cerebri with the bulbospinal grey matter in the medulla oblongata and spinal cord are commonly spoken of as forming the pyramidal tract .

Experimental model of obstetric birth injury of the cervical spinal cord

1998 ◽  
Vol 79 (4) ◽  
pp. 276-279
Author(s):  
A. A. Khasanov ◽  
V. G. Malyshev
Keyword(s):  
Spinal Cord ◽  
Experimental Model ◽  
Reticular Formation ◽  
Vertebral Column ◽  
Cervical Spinal Cord ◽  
Birth Injury ◽  
Experimental Animals ◽  
Vertebral Arteries ◽  
White Substance ◽  
The Brain

The obstetric birth injury is simulated on experimental animals (rats males). During the experiment it was proved that rotations and unbending of the animal's head can result in the trauma of the spinal cord, vertebral column, vertebral arteries, ischemic processes of the reticular formation, white substance of the brain. Neurologic symptomatology of traumatized animals resembles paresis of extremities or myatonic syndrome that are often found in infants. Traumatism of generally recognized obstetric methods is justified.

Congenital neural abnormalities presenting with mirror movements in a patient with Klippel-Feil syndrome

1983 ◽  
Vol 59 (5) ◽  
pp. 891-894 ◽  
Author(s):  
Ian R. Whittle ◽  
Michael Besser
Keyword(s):  
Spinal Cord ◽  
Cervical Spine ◽  
Posterior Fossa ◽  
Pyramidal Tract ◽  
Cervical Spinal Cord ◽  
Content Type ◽  
Mirror Movements ◽  
Posterior Fossa Cyst ◽  
Vertebral Anomalies ◽  
Fine Print

✓ A young girl with Klippel-Feil syndrome presented with the onset of mirror movements in early childhood. Computerized tomography studies of her cervical spine and brain revealed fibrous diastematomyelia with duplication of the cervical spinal cord and an extra-axial midline posterior fossa cyst, together with the multiple cervical vertebral anomalies. Exploration of the posterior fossa lesion revealed it to be a dermoid cyst. The congenital spinal and cord abnormalities found in this case support the hypothesis that the Klippel-Feil syndrome may be associated with variable duplication of the spinal cord and that mirror movements may be related to impairment of pyramidal tract decussation.

Tectospinal and tectoreticular cells: their distribution and afferent connections

1978 ◽  
Vol 56 (4) ◽  
pp. 650-658 ◽  
Author(s):  
P. K. Rose ◽  
V. C. Abrahams
Keyword(s):  
Spinal Cord ◽  
Superior Colliculus ◽  
Reticular Formation ◽  
Cervical Spinal Cord ◽  
Afferent Input ◽  
Cell Populations ◽  
Afferent Connections ◽  
Cells Of Origin ◽  
Muscle Afferent ◽  
Pontine Stimulation

Experiments on chloralose-anaesthetized cats have shown that cells in the superior colliculus may be antidromically activated either from the pontomedullary reticular formation or the ventral cervical spinal cord, or from both sites. In tests on 111 units this has provided a basis for differentiating between cells of origin of the tectospinal tract and the tectoreticular system within the superior colliculus. Tectospinal cells may be activated both by spinal and pontine stimulation; tectoreticular cells cannot be activated by spinal stimulation. Both tectoreticular and tectospinal cells respond to visual and muscle afferent stimulation. The afferent connections may be strongly inhibitory as afferent input to the superior colliculus often prevented subsequent antidromic invasion. This was more commonly seen in tectospinal cells than tectoreticular cells. The distribution of the two cell populations within the superior colliculus was also found to be dissimilar. Evidence has also been obtained to suggest that the tectoreticular system, in part, consists of collaterals of the tectospinal tract.

Development and characterization of pathways descending to the spinal cord in the embryonic chick

1995 ◽  
Vol 73 (3) ◽  
pp. 1223-1233 ◽  
Author(s):  
G. N. Sholomenko ◽  
M. J. O'Donovan
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Motor Activity ◽  
Brain Stem ◽  
Reticular Formation ◽  
Cervical Spinal Cord ◽  
Embryonic Chick ◽  
Medullary Reticular Formation ◽  
Lumbosacral Spinal Cord ◽  
The Brain

1. We used an isolated preparation of the embryonic chick brain stem and spinal cord to examine the origin, trajectory, and effects of descending supraspinal pathways on lumbosacral motor activity. The in vitro preparation remained viable for < or 24 h and was sufficiently stable for electrophysiological, pharmacological, and neuroanatomic examination. In this preparation, as in the isolated spinal cord, spontaneous episodes of both forelimb and hindlimb motor activity occur in the absence of phasic afferent input. Motor activity can also be evoked by brain stem electrical stimulation or modulated by the introduction of neurochemicals to the independently perfused brain stem. 2. At embryonic day (E)6, lumbosacral motor activity could be evoked by brain stem electrical stimulation. At E5, neither brain stem nor spinal cord stimulation evoked activity in the lumbosacral spinal cord, although motoneurons did express spontaneous activity. 3. Lesion and electrophysiological studies indicated that axons traveling in the ventral cord mediated the activation of lumbosacral networks by brain stem stimulation. 4. Partition of the preparation into three separately perfused baths, using a zero-Ca2+ middle bath that encompassed the cervical spinal cord, demonstrated that the brain stem activation of spinal networks could be mediated by long-axoned pathways connecting the brain stem and lumbosacral spinal cord. 5. Using retrograde tracing from the spinal cord combined with brain stem stimulation, we found that the brain stem regions from which spinal activity could be evoked lie in the embryonic reticular formation close to neurons that send long descending axons to the lumbosacral spinal cord. The cells giving rise to these descending pathways are found in the ventral pontine and medullary reticular formation, a region that is the source of reticulospinal neurons important for motor activity in adult vertebrates. 6. Electrical recordings from this region revealed that the activity of some brain stem neurons was synchronized with the electrical activity of lumbosacral motoneurons during evoked or spontaneous episodes of rhythmic motor activity. 7. Both brain stem and spinal cord activity could be modulated by selective application of the glutamate agonist N-methyl-D-aspartate to the brain stem, supporting the existence of functionally active descending projections from the brain stem to the spinal cord. It is not yet clear what role the brain stem activity carried by these pathways has in the genesis and development of spinal cord motor activity.

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