Mossy fiber neck and second-order labyrinthine projections to cat flocculus

In five decerebrate cats and in two under N2O-O2 anesthesia, a bipolar electrode array was inserted into a granular layer in the rostral flocculus. At this location MF field potentials were evoked by stimulation of the ipsilateral vestibular nerve and of the C2 dorsal root ganglion. Stimulation through the array was used to fire brain stem neurons antidromically. The activity of these neurons was recorded extracellularly with glass microelectrodes. Stimulation of the C2 dorsal root ganglion evoked in the caudal lateral brain stem a field potential caused by the arrival of impulses in primary afferent fibers. Cells projecting to the flocculus also responded to the stimulus, usually monosynaptically. These neurons were fired by stimulation of the area of the atlantoaxial joint. They did not respond to stimulation of the contralateral C2 dorsal root ganglion, and responded only rarely to stimulation of the dorsal rami of the C2 and C3 spinal nerves. Stimulation of the vestibular nerve was ineffective. Another group of cells projecting to the flocculus was fired at short latency by stimulation of the ipsilateral vestibular nerve. These neurons were usually inhibited by stimulation of the contralateral vestibular nerve. They were not affected by stimulation of any neck afferents. The location of many recording locations was identified by means of fast green dye marks. Most neurons relaying neck activity were in group x of Brodal and Pompeiano (4), a few were in the external cuneate nucleus, and one was in the descending vestibular nucleus. Neurons relaying labyrinthine activity were in the descending vestibular nucleus; one was found in the medial nucleus, in which tracks were made only rarely. There are two parallel pathways relaying neck and labyrinthine activity to the flocculus. While they are separate at the level of the brain stem, they converge in the same rostral areas of the flocculus. The neck afferent information may be required for proper performance of the flocculus in eye-movement control.

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THE EFFECT OF BOTULINUM TOXIN A ON CHEMICAL STIMULATION OF RAT DORSAL ROOT GANGLION CELLS

The Journal of Urology ◽

10.1016/s0022-5347(08)60225-6 ◽

2008 ◽

Vol 179 (4S) ◽

pp. 77-77

Author(s):

W Stuart Reynolds ◽

Alvaro Lucioni ◽

David E Rapp ◽

Gregory T Bales ◽

Daniel S McGehee

Keyword(s):

Botulinum Toxin ◽

Dorsal Root Ganglion ◽

Dorsal Root ◽

Ganglion Cells ◽

Botulinum Toxin A ◽

Chemical Stimulation ◽

Toxin A ◽

Dorsal Root Ganglion Cells ◽

Stimulation Of

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The Effect of Bipolar Pulsed Radiofrequency Treatment on Chronic Lumbosacral Radicular Pain Refractory to Monopolar Pulsed Radiofrequency Treatment

January 2018 - Pain Physician ◽

10.36076/ppj.2018.2.e97 ◽

2018 ◽

Vol 1 (21;1) ◽

pp. E97-E103 ◽

Cited By ~ 1

Author(s):

Min Cheol Chang

Keyword(s):

Pain Relief ◽

Dorsal Root Ganglion ◽

Dorsal Root ◽

Radicular Pain ◽

Pulsed Radiofrequency ◽

Lumbosacral Radiculopathy ◽

Radiofrequency Treatment ◽

Pulsed Radiofrequency Treatment ◽

Number Of Patients ◽

Stimulation Of

Background: Patients with lumbosacral radicular pain may complain of persisting pain after monopolar pulsed radiofrequency (PRF) treatment. Objective: We evaluated the effect of bipolar PRF stimulation of the dorsal root ganglion (DRG) in patients with chronic lumbosacral radicular pain who were unresponsive to both monopolar PRF stimulation of the DRG and transforaminal epidural steroid injection (TFESI). Study Design: This is a prospective observational study. Setting: The outpatient clinic of a single academic medical center in Korea. Methods: We retrospectively reviewed data from 102 patients who had received monopolar PRF to the DRG for management of lumbosacral radiculopathy. Of these, 32 patients had persistent radicular pain that was scored at least 5 on a numeric rating scale (NRS). Twenty-three of them were included in this study and underwent bipolar PRF of the DRG. The outcomes after the procedure were evaluated using the NRS for radicular pain before treatment and 1, 2, and 3 months after treatment. Successful pain relief was defined as ≥ 50% reduction in the NRS score compared with the score prior to treatment. Furthermore, at 3 months after treatment, patient satisfaction levels were examined. Patients reporting very good (score = 7) or good results (score = 6) were considered to be satisfied with the procedure. Results: The NRS scores changed significantly over time. At 1, 2, and 3 months after bipolar PRF, the NRS scores were significantly reduced compared with the scores before the treatment. Twelve (52.2%) of the 23 patients reported successful pain relief and were satisfied with treatment results 3 months after bipolar PRF. No serious adverse effects were recorded. Limitations: A small number of patients were recruited and we did not perform long-term follow-up. Conclusion: We believe the use of bipolar PRF of the DRG can be an effective and safe interventional technique for chronic refractory lumbosacral radiculopathy. It appears to be a potential option that can be tried before proceeding to spinal surgery. Key words: Bipolar, pulsed radiofrequency, lumbosacral radicular pain, chronic pain, dorsal root ganglion, spinal stenosis, herniated disc

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Functional organization of vestibular and visual inputs to neck and forelimb motoneurons in the frog

Journal of Neurophysiology ◽

10.1152/jn.1977.40.2.225 ◽

1977 ◽

Vol 40 (2) ◽

pp. 225-243 ◽

Cited By ~ 34

Author(s):

M. Maeda ◽

P. C. Magherini ◽

W. Precht

Keyword(s):

Spinal Cord ◽

Optic Nerve ◽

Brain Stem ◽

Optic Tectum ◽

Functional Organization ◽

Vestibular Nerve ◽

Anterior Branch ◽

Visual Inputs ◽

Caudal Level ◽

Stimulation Of

1. Intracellular responses in neck and forelimb motoneurons to electrical stimulation of the vestibular nerve, the optic tectum, and the optic nerve were studied in frog. 2. Stimulation of the anterior branch of the vestibular nerve typically produced EPSPs, bilaterally, in neck, shoulder (DOR), and forelimb extensor (TRI, RAD) motoneurons, and bilateral IPSPs in forelimb adductor (PED) and flexor (ULN, COR) motoneurons. 3. Latencies of PSPs recorded in neck, shoulder, and proximal extensor motoneurons (TRI) were mostly in the disynaptic range, whereas many of those recorded in distal extensor (RAD) and in adductor and flexor motoneurons involved three synapses. 4. Lesion of the vestibulospinal fibers greatly reduced the vestibular nerve-evoked field potentials in the spinal cord and the occurrence of PSPs in forelimb motoneurons. These results as well as the latency measurements suggest that the pathway linking vestibular nerve and forelimb motoneurons mainly consists of vestibulospinal fibers, though involvement of other structures for production of later PSPs could not be completely ruled out. Hemisection of the brain stem at its most caudal level showed that the pathway to the contralateral motoneurons crosses at the level of brain stem as well as in the spinal cord. 5. Stimulation of the optic tectum produced EPSPs, IPSPs, and a mixture of EPSPs and IPSPs in neck, shoulder, and forelimb motoneurons, bilaterally. Most frequently, a combination of an excitation and inhibition was observed. The pathway from the optic tectum to neck and limb motoneurons is at least dysnaptic in nature. 6. Stimulation of the optic nerve produced IPSPs and a mixture of EPSPs and IPSPs in neck and forelimb motoneurons. Impulses originating from the optic nerve descend as far as to lumbar motoneurons producing EPSP-IPSP sequences bilaterally. 7. Interaction studies suggested that the vestibular and optic pathways to neck and forelimb motoneurons are separate from each other so that the site of integration of vestibular and visual input occurs at the level of motoneurons. 8. Evidence for electronic coupling among forelimb motoneurons and electrical synaptic transmission in th pathway linking vestibular nerve and forelimb motoneurons is presented.

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Vertical eye movement-related secondary vestibular neurons ascending in medial longitudinal fasciculus in cat I. Firing properties and projection pathways

Journal of Neurophysiology ◽

10.1152/jn.1990.63.4.902 ◽

1990 ◽

Vol 63 (4) ◽

pp. 902-917 ◽

Cited By ~ 37

Author(s):

Y. Iwamoto ◽

T. Kitama ◽

K. Yoshida

Keyword(s):

Eye Movements ◽

Firing Rate ◽

Vestibular Nucleus ◽

Vestibular Nerve ◽

Medial Longitudinal Fasciculus ◽

Eye Position ◽

Phase Lag ◽

Antidromic Activation ◽

Head Velocity ◽

Stimulation Of

1. The firing characteristics and projection patterns of secondary vestibular nucleus neurons involved in the vertical vestibuloocular pathways were investigated in alert cats. Single-unit recordings were made in the medial longitudinal fasciculus (MLF) near the trochlear nucleus from axons that were monosynaptically activated after electrical stimulation of the vestibular nerve. In a total of 253 identified secondary neurons, 225 discharged in relation to vertical eye movements; 189 of these increased their firing rate for downward eye movements and 36 for upward movements. The activity of the remaining 28 axons was not related to eye movements when the head was still. 2. Virtually all of the secondary neurons with downward on-direction displayed tonic activity that was primarily related to steady eye position during fixation (DPV neurons). The slope of the relationship between firing rate and vertical eye position ranged from 1.2 to 9.1 (spikes/s)/deg with a mean of 3.2 (spikes/s)/deg. The regularity of firing was quantified by calculating the coefficient of variation (CV) of interspike intervals. A comparison of the CV in the population units indicated that DPV neurons could be classified as either regular or irregular neurons. There was a tendency for regular neurons to have higher firing rates and higher correlation coefficients for the rate-position relationships than irregular neurons. 3. During pitch rotation in the light, all the DPV neurons tested increased their firing rate with upward head rotation. Both the phase and the amplitude of the response indicated that DPV neurons discharged not only in relation to eye position but also in relation to head velocity, suggesting that they received monosynaptic input from the posterior semicircular canal. The gain and phase lag of the response relative to head velocity were measured at 0.5 Hz. The range of the gain was 1.1-5.1 (spikes/s)/(deg/s), and that of the phase lag was 18.3-62.4 degrees. There was a tendency for irregular DPV neurons to have a larger gain and smaller phase lag than regular DPV neurons. 4. Ascending and descending projection pathways were determined for 147 DPV axons. Of these, 69 ascended in the contralateral MLF with respect to their soma (crossed-DPV axons), and 78 in the ipsilateral MLF (uncrossed-DPV axons), as revealed by their monosynaptic activation from the contralateral or ipsilateral vestibular nerve. Stimulation of the caudal MLF at the level of the obex evoked direct responses caused by antidromic activation of descending collaterals in approximately 70% (49/69) of the crossed-DPV axons.(ABSTRACT TRUNCATED AT 400 WORDS)

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Excitatory termination of abducens internuclear neurons on medial rectus motoneurons: relationship to syndrome of internuclear ophthalmoplegia

Journal of Neurophysiology ◽

10.1152/jn.1978.41.6.1647 ◽

1978 ◽

Vol 41 (6) ◽

pp. 1647-1661 ◽

Cited By ~ 105

Author(s):

S. M. Highstein ◽

R. Baker

Keyword(s):

Brain Stem ◽

Nerve Stimulation ◽

Physiological Activity ◽

Vestibular Nerve ◽

Medial Rectus ◽

Medial Longitudinal Fasciculus ◽

Internuclear Ophthalmoplegia ◽

Field Potentials ◽

Abducens Nucleus ◽

Stimulation Of

1. Field potentials and intracellular records were obtained from the medial rectus subdivision of the IIIrd nucleus in anesthetized cats following electrical stimulation of the abducens nuclei, vestibular nerves, pontomedullary brain stem, and the medial longitudinal fasciculi (MLF). 2. Stimulation of the contralateral abducens nucleus produced unique field potentials in the medial rectus subdivision. They consisted of an early sharp transient volley followed by a slower postsynaptic negativity. 3. Monosynaptic EPSPs were evoked in medial rectus motoneurons following contralateral abducens nucleus stimulation. The EPSP amplitudes were graded when the stimulus intensity was increased from threshold to supramaximal. EPSPs produced by contralateral abducens nucleus stimulation were larger in amplitude than those produced by ipsilateral vestibular nerve stimulation. The current-voltage relationship and reversal potentials for Vi- and abducens-evoked EPSPs were similar and indicated an overlapping location of excitatory synaptic terminals on medial rectus motoneurons. 4. Secondary vestibular axons activated monosynaptically by ipsilateral vestibular nerve stimulation were not recruited by abducens nucleus stimulation. 5. Ipsilateral MLF stimulation produced EPSPs with similar profiles as those observed following abducens nucleus stimulation; however, stimulation of the contralateral MLF at comparable stimulus intensities did not produce any changes in transmembrane potential. 6. When higher intensity stimuli were applied to the contralateral MLF, the synaptic potentials recorded in the medial rectus were occluded by those produced by weaker stimulation applied to the ipsilateral MLF. This suggests that the potentials resulting from stronger contralateral stimulation were due to current spread to the ipsilateral MLF. 7. While recording in the medial rectus subdivision, various sites in the ponto-medullary brain stem were explored with a stimulating electrode. Analysis of evoked field potentials suggested that the ascending internuclear axons were contained only in the MLF ipsilateral to the medial rectus. Acute brain stem lesions confirmed this suggestion. 8. Chronic lesions were placed in the brain stem to isolate the abducens nucleus from either extrinsic fibers of passage or axon collaterals. Acute electrophysiological experiments in these chronic animals corroborated the suggestion that the medial rectus pathway originated from within the abducens nucleus. 9. We conclude that axons from the internuclear neurons of the abducens nucleus exit from the nucleus medially, cross the midline, ascend in the opposite MLF, and terminate monosynaptically on medial rectus motoneurons. 10. we believe that the syndrome of internuclear ophthalmoplegia associated clinically with lesions of the medial longitudinal fasciculus could be due to the absence of ascending physiological activity from internuclear neurons of the abducens nucleus.

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