Convergence in the sensory zones of the dorsal roots of the spinal cord during stimulation of muscular afferent nerves

1967 ◽  
Vol 63 (6) ◽  
pp. 571-573
Author(s):  
A. M. Mamedova ◽  
A. A. Oganisyan
Keyword(s):  
Spinal Cord ◽  
Dorsal Roots ◽  
Afferent Nerves ◽  
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.

Neurons of rostral ventrolateral medulla mediate somatic pressor reflex

1989 ◽  
Vol 256 (2) ◽  
pp. R448-R462 ◽  
Author(s):  
R. L. Stornetta ◽  
S. F. Morrison ◽  
D. A. Ruggiero ◽  
D. J. Reis
Keyword(s):  
Spinal Cord ◽  
Kainic Acid ◽  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Reticular Nucleus ◽  
Lumbar Spinal Cord ◽  
Afferent Nerves ◽  
Electrolytic Lesions ◽  
Pressor Reflex ◽  
Stimulation Of

The somatic pressor reflex (SPR) elicited in anesthetized paralyzed rats by electrical stimulation of the sciatic or sural cutaneous afferent nerves produced an increase in arterial pressure ranging from 5 to 40 mmHg. Stimulation of femoral or tibial afferent nerves from muscle produced a depressor response. The SPR was not affected by midpontine transection but was eliminated either by hemisection of the lumbar spinal cord contralateral, but not ipsilateral, to the stimulated nerve or by electrolytic or kainic acid lesion of the contralateral, but not ipsilateral, rostral ventrolateral medulla (RVL). Stimulation of the brachial plexus elicited an SPR that was not eliminated by contralateral lumbar hemisection but was abolished by RVL lesion. RVL lesions consistently overlapped areas containing phenylethanolamine N-methyltransferase-labeled C1 adrenergic neurons. Kainic acid injections into the lateral reticular nucleus (LRN) did not affect the SPR. Neither contralateral nor ipsilateral electrolytic lesions of other autonomic areas including parabrachial nucleus, the nucleus tractus solitarii, the A5 region, or the inferior cerebellar peduncle (output pathway of the LRN) affected the reflex. In axonal transport studies using horseradish peroxidase, afferent terminals of the sciatic nerve were shown to overlap spinoreticular neurons in the dorsal horn retrogradely labeled from tracer injections in the RVL. We conclude that the SPR can be elicited in rats, that it is mediated by spinoreticular afferents traveling in the contralateral spinal cord, and that the C1 adrenergic area of the RVL is a critical region for the integration of the somatic pressor reflex.

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.

Specific and nonspecific mechanisms involved in generation of PAD of group Ia afferents in cat spinal cord

1984 ◽  
Vol 52 (5) ◽  
pp. 921-940 ◽  
Author(s):  
I. Jimenez ◽  
P. Rudomin ◽  
M. Solodkin ◽  
L. Vyklicky
Keyword(s):  
Spinal Cord ◽  
Muscle Afferents ◽  
Potassium Ions ◽  
Single Group ◽  
Individual Group ◽  
Afferent Nerves ◽  
Group I ◽  
Stimulation Of ◽  
Anesthetized Cat ◽  
Site Stimulation

In the spinal cord of the anesthetized cat, we measured the changes in extracellular concentration of potassium ions [K+]e and the negative DC shifts produced by stimulation of muscle, cutaneous and mixed afferent nerves, together with alterations in the threshold of single group Ia fibers that were tested at the same site as the potassium measurements. This approach provided information on the extent to which the excitability changes of single Ia-fibers can be correlated with the changes in [K+]e occurring at the same site. Stimulation of the tibial (TIB) nerve and of the cutaneous sural (SU), and superficial peroneous (SP) nerve (100-Hz trains lasting 30-60 s) with stimulus strengths of 10-15 times threshold increased the concentration of [K+]e in the dorsal horn by 2-5 mmol/l above the resting value of 3 mmol/l. This was in clear contrast with the very small [K+]e increases produced at the same site during stimulation of muscle nerves, such as the posterior biceps and semitendinosus (PBSt), gastrocnemius soleus (GS), and deep peroneus (DP), which were generally smaller than 0.25 mmol/l. Stimulation of the PBSt and GS muscle nerves did produce small, but clear, increases of [K+]e (up to 0.3 mmol/l) in the region of the intermediate nucleus, where these fibers synapse with second order cells. These changes were nevertheless smaller than those produced at the same site by stimulation of the TIB, SU, and SP nerves. The peak amplitudes of the [K+]e transients produced by long-lasting 100-Hz trains applied to cutaneous and/or to muscle nerves showed a linear relationship with the amplitudes of the slow negative DC shifts, which were simultaneously recorded from the NaCl barrel of the potassium electrode assembly. Stimulus trains (100 Hz) applied to group I muscle afferents (PBSt and DP) very effectively reduced the threshold for intraspinal activation of individual group I GS fibers but produced negligible negative DC shifts at the same site. On the other hand, 100-Hz stimulus trains applied to the SU and SP nerves produced large negative DC shifts, even with low-stimulus strengths (2 X T, where T is threshold), but had much smaller effects on the threshold of group Ia GS fibers. Increasing the intensity of the stimuli applied to cutaneous and mixed nerves above 2 X T strength further reduced the threshold of the Ia-fibers.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Plasticity of urinary bladder reflexes evoked by stimulation of pudendal afferent nerves after chronic spinal cord injury in cats

2011 ◽  
Vol 228 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Changfeng Tai ◽  
Mang Chen ◽  
Bing Shen ◽  
Jicheng Wang ◽  
Hailong Liu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Urinary Bladder ◽  
Chronic Spinal Cord Injury ◽  
Afferent Nerves ◽  
Cord Injury ◽  
Stimulation Of
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