Synaptic effects on frog motoneurons during stimulation of the dorsal roots and posterior columns of the spinal cord

1971 ◽  
Vol 71 (5) ◽  
pp. 476-479
Author(s):  
B. I. Shiryaev
Keyword(s):  
Spinal Cord ◽  
Dorsal Roots ◽  
Synaptic Effects ◽  
Stimulation Of

Electrophysiological Assessment of Spinal Circuits in Spasticity by Direct Dorsal Root Stimulation

Neurosurgery ◽  
1979 ◽  
Vol 4 (2) ◽  
pp. 146-151 ◽  
Author(s):  
Victor Aldo Fasano ◽  
Giancarlo Barolat-Romana ◽  
Sergio Zeme ◽  
Angelo Sguazzi
Keyword(s):  
Spinal Cord ◽  
Muscle Tone ◽  
Basic Mechanism ◽  
Common Finding ◽  
Inhibitory Processes ◽  
Positive Effects ◽  
Dorsal Roots ◽  
Spinal Roots ◽  
Dorsal Spinal ◽  
Stimulation Of

Abstract Experimental researchers have shown that, because of normal inhibitory processes, repetitive orthodromic stimulation of the dorsal spinal roots induces a depression of the reflex discharge in the spinal motoneurons that is a function of the stimulation rate. Because a lack of inhibitory processes is considered to be the basic mechanism of spasticity, intraoperative stimulation of dorsal spinal roots from L-1 to S-1 bilaterally was performed in 80 patients affected by cerebral palsy. In these patients spasticity (exaggerated stretch reflexes, marked increase of proprioceptive reflexes, and clonus) was the main symptom. We stimulated the dorsal roots adjacent to the spinal cord and recorded motor responses by electromyogram (EMG) in the corresponding muscle groups. The most important findings were that: (a) variable inhibition (diminished, increased, or normal) was encountered in the spinal circuits of the spastic patient; and (b) the individual roots and rootlets can have different effects upon segmentary output. The absence of normal inhibitory processes was the most common finding; surgical sectioning of the corresponding roots resulted in immediate reduction in muscle tone in the related muscles. Selecting the dorsal roots for section results in a remarkable reduction of negative side effects that may follow total or random rhizotomy (marked hypotonia, ataxia, sensory defects) and of the percentage of late recurrences. This procedure results in additional positive effects at segmentary and suprasegmentary levels. These results confirm the idea that the basic mechanism of spasticity is a central defect in the traffic regulation of peripheral afferents as they are transmitted to the spinal cord. This defect causes segmentary and suprasegmentary adaptive reactions that extend the negative outcome of the local increase of muscle tone.

Ascending pressor and depressor pathways in the cat spinal cord

1976 ◽  
Vol 231 (3) ◽  
pp. 786-792 ◽  
Author(s):  
JM Chung ◽  
RD Wurster
Keyword(s):  
Spinal Cord ◽  
High Frequency Stimulation ◽  
Optimal Frequency ◽  
Dorsal Roots ◽  
Pressor Responses ◽  
Frequency Stimulation ◽  
Blood Pressure Responses ◽  
Bilateral Lesions ◽  
Site Of Stimulation ◽  
Stimulation Of

Blood pressure responses to stimulation of the cervical dorsolateral sulcus (DLS) of the spinal cord and lumbar dorsal roots were studied in anesthetized, vagotomized, and paralyzed cats. Stimulation of the lumbar dorsal roots elicited pressor responses with high-frequency stimulation (50 Hz, 10 V, 1 ms) and depressor responses with low-grequency stimulation (1 Hz, 10 V, 1 ms). Pressor responses were converted to depressor responses after bilateral lesions were made in the DLS area rostral to the site of stimulation. These results suggest that the ascending spinal pressor pathways are localized in the DLS region. Furthermore, these depressor responses were abolished by placing additional bilateral lesions in the dorsolateral funiculus (DLF) rostral to the site of stimulation. These data indicate the presence of ascending depressor pathways in the DLF which are anatomically separate from pressor pathways. Both pathways were found to be bilateral systems, and decussation of fibers appears to be complete within three segments rostral to their entry into the spinal cord. Ascending depressor pathways have a low optimal frequency of activation, as opposed to the ascending pressor pathways which have a relatively high optimal frequency of activation. Neurophysiological evidence obtained by recording unit activity from the cervical sympathetic trunk confirmed the localization of the ascending pressor and depressor pathways.

The Neurological Basis of the Locomotory Rhythm in the Spinal Dogfish (Scyllium Canicula, Acanthias Vulgaris)

1946 ◽  
Vol 23 (2) ◽  
pp. 162-176 ◽  
Author(s):  
H. W. LISSMANN
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Electrical Stimulation ◽  
Posterior Half ◽  
Automatic Activity ◽  
Dorsal Roots ◽  
The Central Nervous System ◽  
Stimulation Of

Some of the more striking effects of de-afferentation in the spinal dogfish are diagrammatically represented in Fig. 13. 1. The persistent locomotory rhythm of a spinal dogfish depends upon afferent excitation. If all afferent excitation is cut off by severance of all dorsal roots, the rhythm is abolished (Fig. 13, 1). 2. The rhythm clearly emerges when about half the number of all the dorsal roots is transected, irrespective whether the anterior or the posterior half of the animal be de-afferentated (Fig. 13, 2 and 3), or whether complete unilateral de-afferentation is executed (Fig. 13, 4). 3. Extensively de-afferentated preparations may exhibit swimming movements after exteroceptive stimulation. These swimming movements do not persist. 4. Preparations de-afferentated except for the tail exhibit after exteroceptive stimulation a static reflex posture. 5. The de-afferentated musculature takes part in both tonic and rhythmic responses as long as it is connected through the spinal cord with normally innervated musculature. 6. In response to electrical stimulation applied to the cord of a spinal dogfish two distinct types of rhythmic response have been evoked. 7. No rhythmic responses have bee obtained through electrical stimulation of the spinal cord in completely de-afferentated preparations. 8. No evidence has been found in support of the view that the swimming rhythm emanates through a spontaneous, automatic activity from the central nervous system.

scholarly journals Maintenance of contractile force of the hind limb muscles by the somato-lumbar sympathetic reflexes

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Harumi Hotta ◽  
Kaori Iimura ◽  
Nobuhiro Watanabe ◽  
Kazuhiro Shigemoto
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Sympathetic Nerve ◽  
Skeletal Muscles ◽  
Sympathetic Nerves ◽  
Contractile Force ◽  
Triceps Surae ◽  
Dorsal Roots ◽  
Before And After ◽  
Stimulation Of

AbstractThis study aimed to clarify whether the reflex excitation of muscle sympathetic nerves induced by contractions of the skeletal muscles modulates their contractility. In anesthetized rats, isometric tetanic contractions of the triceps surae muscles were induced by electrical stimulation of the intact tibial nerve before and after transection of the lumbar sympathetic trunk (LST), spinal cord, or dorsal roots. The amplitude of the tetanic force (TF) was reduced by approximately 10% at 20 min after transection of the LST, spinal cord, or dorsal roots. The recorded postganglionic sympathetic nerve activity from the lumbar gray ramus revealed that both spinal and supraspinal reflexes were induced in response to the contractions. Repetitive electrical stimulation of the cut peripheral end of the LST increased the TF amplitude. Our results indicated that the spinal and supraspinal somato-sympathetic nerve reflexes induced by contractions of the skeletal muscles contribute to the maintenance of their own contractile force.

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