Inputs from regularly and irregularly discharging vestibular nerve afferents to secondary neurons in squirrel monkey vestibular nuclei. III. Correlation with vestibulospinal and vestibuloocular output pathways

1992 ◽  
Vol 68 (2) ◽  
pp. 471-484 ◽  
Author(s):  
R. Boyle ◽  
J. M. Goldberg ◽  
S. M. Highstein
Keyword(s):  
Spinal Cord ◽  
Transition Zone ◽  
Vestibular Nucleus ◽  
Vestibular Nuclei ◽  
Vestibular Nerve ◽  
Descending Pathways ◽  
Relative Contribution ◽  
Antidromic Stimulation ◽  
Vestibulospinal Tract ◽  
Irregular Afferents

1. A previous study measured the relative contributions made by regularly and irregularly discharging afferents to the monosynaptic vestibular nerve (Vi) input of individual secondary neurons located in and around the superior vestibular nucleus of barbiturate-anesthetized squirrel monkeys. Here, the analysis is extended to more caudal regions of the vestibular nuclei, which are a major source of both vestibuloocular and vestibulospinal pathways. As in the previous study, antidromic stimulation techniques are used to classify secondary neurons as oculomotor or spinal projecting. In addition, spinal-projecting neurons are distinguished by their descending pathways, their termination levels in the spinal cord, and their collateral projections to the IIIrd nucleus. 2. Monosynaptic excitatory postsynaptic potentials (EPSPs) were recorded intracellularly from secondary neurons as shocks of increasing strength were applied to Vi. Shocks were normalized in terms of the threshold (T) required to evoke field potentials in the vestibular nuclei. As shown previously, the relative contribution of irregular afferents to the total monosynaptic Vi input of each secondary neuron can be expressed as a %I index, the ratio (x100) of the relative sizes of the EPSPs evoked by shocks of 4 x T and 16 x T. 3. Antidromic stimulation was used to type secondary neurons as 1) medial vestibulospinal tract (MVST) cells projecting to spinal segments C1 or C6; 2) lateral vestibulospinal tract (LVST) cells projecting to C1, C6; or L1; 3) vestibulooculo-collic (VOC) cells projecting both to the IIIrd nucleus and by way of the MVST to C1 or C6; and 4) vestibuloocular (VOR) neurons projecting to the IIIrd nucleus but not to the spinal cord. Most of the neurons were located in the lateral vestibular nucleus (LV), including its dorsal (dLV) and ventral (vLV) divisions, and adjacent parts of the medial (MV) and descending nuclei (DV). Cells receiving quite different proportions of their direct inputs from regular and irregular afferents were intermingled in all regions explored. 4. LVST neurons are restricted to LV and DV and show a somatotopic organization. Those destined for the cervical and thoracic cord come from vLV, from a transition zone between vLV and DV, and to a lesser extent from dLV. Lumbar-projecting neurons are located more dorsally in dLV and more caudally in DV. MVST neurons reside in MV and in the vLV-DV transition zone.(ABSTRACT TRUNCATED AT 400 WORDS)

Inputs from regularly and irregularly discharging vestibular nerve afferents to secondary neurons in the vestibular nuclei of the squirrel monkey. II. Correlation with output pathways of secondary neurons

1987 ◽  
Vol 58 (4) ◽  
pp. 719-738 ◽  
Author(s):  
S. M. Highstein ◽  
J. M. Goldberg ◽  
A. K. Moschovakis ◽  
C. Fernandez
Keyword(s):  
Spinal Cord ◽  
Vestibular Nucleus ◽  
Preceding Paper ◽  
Vestibular Nuclei ◽  
Vestibular Nerve ◽  
Antidromic Activation ◽  
Mean Values ◽  
Postsynaptic Potentials ◽  
The Mean ◽  
Vestibular Nerve Afferents

1. Intracellular recordings were made from secondary neurons in the vestibular nuclei of barbiturate-anesthetized squirrel monkeys. Monosynaptic excitatory postsynaptic potentials (EPSPs) evoked by stimulation of the ipsilateral vestibular nerve (Vi) were measured. An electrophysiological paradigm, described in the preceding paper (26), was used to determine the proportion of irregularly (I) and regularly (R) discharging Vi afferents making direct connections with individual secondary neurons. The results were expressed as a % I index, an estimate for each neuron of the percentage of the total Vi monosynaptic input that was derived from I afferents. The secondary neurons were also classified as I, R, or M cells, depending on whether they received their direct Vi inputs predominantly from I or R afferents or else from a mixture (M) of both kinds of Vi fibers. The neurons were located in the superior vestibular nucleus (SVN) or in the rostral parts of the medical or lateral (LVN) vestibular nuclei. 2. Antidromic activation or reconstruction of axonal trajectories after intrasomatic injection of horseradish peroxidase (HRP) was used to identify three classes of secondary neurons in terms of their output pathways: 1) cerebellar-projecting (Fl) cells innervating the flocculus (n = 26); 2) rostrally projecting (Oc) cells whose axons ascended toward the oculomotor (IIIrd) nucleus (n = 27); and 3) caudally projecting (Sp) cells with axons descending toward the spinal cord (n = 13). Two additional neurons, out of 21 tested, could be antidromically activated both from the level of the IIIrd nucleus and from the spinal cord. 3. The Vi inputs to the various classes of relay neurons differed. As a class, Oc neurons received the most regular inputs. Sp neurons had more irregular inputs. Fl neurons were heterogeneous with similar numbers of R, M, and I neurons. The mean values (+/- SD) of the % I index for the Oc, Fl, and Sp neurons were 34.7 +/- 24.7, 51.9 +/- 30.4, and 61.8 +/- 18.0%, respectively. Only the Oc neurons had a % I index that was similar to the proportion of I afferents (34%) in the vestibular nerve (cf. Ref. 26). 4. The commissural inputs from the contralateral vestibular nerve (Vc) also differed for the three projection classes. Commissural inhibition was most common in Fl cells: 22/25 (88%) of the neurons had Vc inhibitory postsynaptic potentials (IPSPs) and 1/25 (4%) had a Vc EPSP. In contrast, Vc inputs were only observed in approximately half the Oc and Sp neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Inputs from regularly and irregularly discharging vestibular nerve afferents to secondary neurons in the vestibular nuclei of the squirrel monkey. I. An electrophysiological analysis

1987 ◽  
Vol 58 (4) ◽  
pp. 700-718 ◽  
Author(s):  
J. M. Goldberg ◽  
S. M. Highstein ◽  
A. K. Moschovakis ◽  
C. Fernandez
Keyword(s):  
Vestibular Nucleus ◽  
Field Potential ◽  
Vestibular Nuclei ◽  
Afferent Input ◽  
Vestibular Nerve ◽  
Shock Strength ◽  
Electrical Excitability ◽  
Naturally Occurring ◽  
Test Shock ◽  
Vestibular Nerve Afferents

1. The electrical excitability of vestibular nerve afferents is related to their discharge regularity (23). Irregular (I) afferents are more excitable than regular (R) afferents. We explored the possibility that the differences in electrical excitability could be used to determine the profile of monosynaptic inputs from the ipsilateral vestibular nerve (Vi) to secondary neurons of the vestibular nuclei. The growth of monosynaptic Vi excitatory postsynaptic potentials (EPSPs) as shock strength is increased should reflect the kinds of afferent input that a secondary neuron receives. We were particularly interested in seeing if cells in the vestibular nuclei could be distinguished as R or I neurons depending on whether they received predominantly regular or irregular inputs. Barbiturate-anesthetized squirrel monkeys were used. 2. Recordings were made from vestibular nerve afferents. Shock strength was expressed as multiples of T, the value needed to recruit 10% of the afferents or, as determined empirically, to evoke a detectable field potential in the vestibular nuclei. Most I afferents (85/87 = 98%) were recruited below 4 X T, whereas most R afferents (197/212 = 93%) were first activated above 4 X T. The relation between latent period and electrical excitability was flat for units with thresholds in the range 1-4 X T. Latent periods increased for units with higher thresholds, especially those first activated above 8 x T. The threshold differences between I and R afferents are maximal if the shock falls at approximately half the mean interval after a naturally occurring action potential. The same results were obtained by having each unit fire to a maximal (16-32 X T) conditioning shock and then determining the threshold to a test shock presented 4 ms later. The latter stimulus configuration was used to study the Vi monosynaptic inputs to secondary neurons. The test shock was raised by successive doublings from 1 X T to the strength of the conditioning shock (16-32 X T). 3. Intracellular recordings were made from neurons located in the superior vestibular nucleus or the rostral parts of the medical or lateral vestibular nuclei. Amplitudes and latent periods of Vi EPSPs were measured from averages of several repetitions of each stimulus pair. Each EPSP was calculated by subtracting the extracellular from the intracellular averaged response. Of the 122 neurons sampled, 115 were judged to be monosynaptically related to the ipsilateral vestibular nerve because their Vi EPSPs had latent periods in the range of 0.7-1.4 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Vestibular nuclear complex in cattle: Topography, morphology, cytoarchitecture and lumbo-sacral projections

2007 ◽  
Vol 17 (1) ◽  
pp. 9-24 ◽  
Author(s):  
Annamaria Grandis ◽  
Cristiano Bombardi ◽  
Beatrice Travostini ◽  
Arcangelo Gentile ◽  
Monica Joechler ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Vestibular Nucleus ◽  
Vestibular Nuclei ◽  
Analysis Software ◽  
Fluorescent Tracer ◽  
Minimum Diameter ◽  
Nuclear Complex ◽  
Dorsal Portion ◽  
Vestibular Nuclear Complex ◽  
Intermediate Size

The topography and the main characteristics of the vestibular nuclear complex (VNC) in cattle have been studied in serially transversally cut Nissl and Gles-stained sections. By using computerized image analysis software, the cell size, the maximum and minimum diameter of the neurons of each vestibular nucleus were obtained. These parameters were statistically analyzed by comparing the cell population from different nuclei and different parts of each nucleus. Furthermore, in order to investigate the lumbo-sacral projections, the fluorescent tracer Fast Blue was injected into the L6-S1 spinal cord of three calves. Among the vestibular nuclei, the superior was the least extensive rostro-caudally, the medial was the most extensive and contained the smallest cells, the lateral showed the largest neurons, and the descending nucleus contained cells of intermediate size which decreased in a rostrocaudal direction. Concerning the lumbo-sacral projections of the bovine VNC, the present study showed that only the fibers coming from the lateral vestibular nucleus reached the L6-S1 spinal cord. The labelled neurons were most heavily concentrated in the dorsal portion of this nucleus, but scattered neurons were also observed throughout the entire extension of the nucleus. The differences between the descriptions of cattle and other species were described.

Effect of Spinal Cord Transection on Spontaneous Activity Recorded from Type I Neurons of the Medial Vestibular Nucleus in Compensated Hemilabyrinthectomized Gerbils

1985 ◽  
Vol 93 (3) ◽  
pp. 414-418 ◽  
Author(s):  
Thomas J. Clegg ◽  
Adrian A. Perachio
Keyword(s):  
Spinal Cord ◽  
Spontaneous Activity ◽  
Inhibitory Control ◽  
Vestibular Nucleus ◽  
Vestibular Nuclei ◽  
Spinal Cord Transection ◽  
Medial Vestibular Nucleus ◽  
Type I ◽  
Intact Side ◽  
Injured Side

Spontaneous activity was recorded from type I neurons of the medial vestibular nuclei (MVN) in unanesthetized, decerebrate gerbils to determine the effect of spinal cord transection on compensation following labyrinthectomy. Immediately after labyrinthectomy there was an increase in activity of type I neurons on the intact side and an absence of activity on the injured side. Following compensation from labyrinthectomy, the distribution and activity rates approximated those of nonlabyrinthectomized animals. Spinal cord transection resulted in an increase in activity in type I MVN neurons contralateral to the labyrinthectomy in compensated animals and bilaterally in nonlabyrinthectomized animals. These results illustrate that type I neurons apparently are under an indirect inhibitory control from both the contralateral labyrinth and the spinal cord. In compensated animals spinal cord inhibition exists only on the intact side. This suggests that the symmetry in type I activity bilaterally in the compensated animal is in part the result of asymmetric spinal cord input.

Abnormal Spinal Cord Myelination due to Oligodendrocyte Dysfunction in a Model of Huntington’s Disease

2021 ◽  
pp. 1-8
Author(s):  
Costanza Ferrari Bardile ◽  
Harwin Sidik ◽  
Reynard Quek ◽  
Nur Amirah Binte Mohammad Yusof ◽  
Marta Garcia-Miralles ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Oligodendrocyte Progenitor Cells ◽  
Wild Type ◽  
Specific Expression ◽  
Relative Contribution ◽  
Related Proteins ◽  
The Impact ◽  
Cervical Area

Background: The relative contribution of grey matter (GM) and white matter (WM) degeneration to the progressive brain atrophy in Huntington’s disease (HD) has been well studied. The pathology of the spinal cord in HD is comparatively less well documented. Objective: We aim to characterize spinal cord WM abnormalities in a mouse model of HD and evaluate whether selective removal of mutant huntingtin (mHTT) from oligodendroglia rescues these deficits. Methods: Histological assessments were used to determine the area of GM and WM in the spinal cord of 12-month-old BACHD mice, while electron microscopy was used to analyze myelin fibers in the cervical area of the spinal cord. To investigate the impact of inactivation of mHTT in oligodendroglia on these measures, we used the previously described BACHDxNG2Cre mouse line where mHTT is specifically reduced in oligodendrocyte progenitor cells. Results: We show that spinal GM and WM areas are significantly atrophied in HD mice compared to wild-type controls. We further demonstrate that specific reduction of mHTT in oligodendroglial cells rescues the atrophy of spinal cord WM, but not GM, observed in HD mice. Inactivation of mHTT in oligodendroglia had no effect on the density of oligodendroglial cells but enhanced the expression of myelin-related proteins in the spinal cord. Conclusion: Our findings demonstrate that the myelination abnormalities observed in brain WM structures in HD extend to the spinal cord and suggest that specific expression of mHTT in oligodendrocytes contributes to such abnormalities.

Relationship of Semicircular Canal Size to Vestibular-Nerve Afferent Sensitivity in Mammals

2007 ◽  
Vol 98 (6) ◽  
pp. 3197-3205 ◽  
Author(s):  
Aizhen Yang ◽  
Timothy E. Hullar
Keyword(s):  
Semicircular Canal ◽  
High Frequency ◽  
High Gain ◽  
Vestibular Nerve ◽  
Radius Of Curvature ◽  
Horizontal Canal ◽  
Vestibular Nerve Afferents ◽  
The Relationship ◽  
Irregular Afferents ◽  
Anterior Canal

The relationship between semicircular canal radius of curvature and afferent sensitivity has not been experimentally determined. We characterized mouse semicircular canal afferent responses to sinusoidal head rotations to facilitate interspecies and intraspecies comparisons of canal size to sensitivity. The interspecies experiment compared the horizontal canal afferent responses among animals ranging in size from mouse to rhesus monkey. The intraspecies experiment compared afferent responses from the larger anterior canal to those from the smaller horizontal canal of mice. The responses of mouse vestibular-nerve afferents showed a low- and high-frequency phase lead and high-frequency gain enhancement. Regular horizontal-canal afferents showed a sensitivity to 0.5-Hz sinusoidal rotations of 0.10 ± 0.03 (SD) spike · s−1/deg · s−1 and high-gain irregular afferents showed a sensitivity of 0.25 ± 0.11 spike · s−1/deg · s−1. The interspecies comparison showed that the sensitivity of regular afferents was related to the radius of curvature R according to the formula Gr = 0.23R − 0.09 ( r2 = 0.86) and the sensitivity of irregular afferents was related to radius according to the formula Gi = 0.32R + 0.01 ( r2 = 0.67). The intraspecies comparison showed that regularly firing anterior canal afferents were significantly more sensitive than those from the relatively smaller horizontal canal, with Gr = 0.25R. This suggests that canal radius of curvature is closely related to afferent sensitivity both among and within species. If the relationship in humans is similar to that demonstrated here, the sensitivity of their regular vestibular-nerve afferents to 0.5-Hz rotations is likely to be about 0.67 spike · s−1/deg · s−1 and of their high-gain irregular afferents about 1.06 spikes · s−1/deg · s−1.

Motor projection patterns to the hind limb of normal and paralysed chick embryos

Development ◽  
1982 ◽  
Vol 72 (1) ◽  
pp. 269-286
Author(s):  
N. G. Laing
Keyword(s):  
Spinal Cord ◽  
Cell Death ◽  
Hind Limb ◽  
Muscle Volume ◽  
Chick Embryos ◽  
Relative Contribution ◽  
Hind Limbs ◽  
Lateral Motor Column ◽  
Before And After ◽  
Major Period

Counts were made of the number of motoneurons innervating the hind limbs of 10-day normal and paralysed chick embryos whose right hind limb buds had been subjected to varying degrees of amputation prior to innervation. The number of motoneurons on the intact sides of the paralysed embryos was found to be similar to the number present in normal embryos prior to the major period of motoneuron death. Since it has previously been shown that paralysis does not increase the number of motoneurons generated, this means that normal motoneuron death was largely prevented in the paralysed embryos. There were differences in the distributions of motoneurons in the rostrocaudal axis of the spinal cord between normal and paralysed embryos. Therefore, cell death does not eliminate a uniform fraction of motoneurons throughout the rostrocaudal extent of the chick embryo lumbar lateral motor column. It is also argued that there are differences in the relative contribution of the various lumbosacral levels to different parts of the limb, e.g. the shank, before and after the period of cell death. In both normal and paralysed embryos there was a linear relationship between the volume of limb muscle which developed after amputation and the number of motoneurons surviving in the spinal cord. There was no evidence of a ‘compression’ of motoneurons into the remaining muscle either after amputation alone or after amputation combined with paralysis. Motoneurons are therefore rigidly specified for certain parts of the limb. The relationship between motoneuron number and muscle volume on the amputated side differed from that of the intact side. For a similar increase in muscle volume there was a smaller increase in motoneuron number on the intact sides. This suggested a parallel to the paradoxically small increase in motoneuron number that occurs on the addition of a supernumerary limb.

scholarly journals Functional Brain Connectivity during Multiple Motor Imagery Tasks in Spinal Cord Injury

2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Alkinoos Athanasiou ◽  
Nikos Terzopoulos ◽  
Niki Pandria ◽  
Ioannis Xygonakis ◽  
Nicolas Foroglou ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Functional Connectivity ◽  
Motor Imagery ◽  
Healthy Subjects ◽  
Brain Connectivity ◽  
Descending Pathways ◽  
Brain Organization ◽  
Sensorimotor Network ◽  
Cord Injury

Reciprocal communication of the central and peripheral nervous systems is compromised during spinal cord injury due to neurotrauma of ascending and descending pathways. Changes in brain organization after spinal cord injury have been associated with differences in prognosis. Changes in functional connectivity may also serve as injury biomarkers. Most studies on functional connectivity have focused on chronic complete injury or resting-state condition. In our study, ten right-handed patients with incomplete spinal cord injury and ten age- and gender-matched healthy controls performed multiple visual motor imagery tasks of upper extremities and walking under high-resolution electroencephalography recording. Directed transfer function was used to study connectivity at the cortical source space between sensorimotor nodes. Chronic disruption of reciprocal communication in incomplete injury could result in permanent significant decrease of connectivity in a subset of the sensorimotor network, regardless of positive or negative neurological outcome. Cingulate motor areas consistently contributed the larger outflow (right) and received the higher inflow (left) among all nodes, across all motor imagery categories, in both groups. Injured subjects had higher outflow from left cingulate than healthy subjects and higher inflow in right cingulate than healthy subjects. Alpha networks were less dense, showing less integration and more segregation than beta networks. Spinal cord injury patients showed signs of increased local processing as adaptive mechanism. This trial is registered with NCT02443558.

scholarly journals Convergence of linear acceleration and yaw rotation signals on non-eye movement neurons in the vestibular nucleus of macaques

2018 ◽  
Vol 119 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Shawn D. Newlands ◽  
Ben Abbatematteo ◽  
Min Wei ◽  
Laurel H. Carney ◽  
Hongge Luan
Keyword(s):  
Eye Movement ◽  
Multisensory Integration ◽  
Vestibular Nucleus ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Vestibular Nuclei ◽  
Otolith Organs ◽  
Angular Rotation ◽  
Sensory Signals ◽  
Nonlinear Integration

Roughly half of all vestibular nucleus neurons without eye movement sensitivity respond to both angular rotation and linear acceleration. Linear acceleration signals arise from otolith organs, and rotation signals arise from semicircular canals. In the vestibular nerve, these signals are carried by different afferents. Vestibular nucleus neurons represent the first point of convergence for these distinct sensory signals. This study systematically evaluated how rotational and translational signals interact in single neurons in the vestibular nuclei: multisensory integration at the first opportunity for convergence between these two independent vestibular sensory signals. Single-unit recordings were made from the vestibular nuclei of awake macaques during yaw rotation, translation in the horizontal plane, and combinations of rotation and translation at different frequencies. The overall response magnitude of the combined translation and rotation was generally less than the sum of the magnitudes in responses to the stimuli applied independently. However, we found that under conditions in which the peaks of the rotational and translational responses were coincident these signals were approximately additive. With presentation of rotation and translation at different frequencies, rotation was attenuated more than translation, regardless of which was at a higher frequency. These data suggest a nonlinear interaction between these two sensory modalities in the vestibular nuclei, in which coincident peak responses are proportionally stronger than other, off-peak interactions. These results are similar to those reported for other forms of multisensory integration, such as audio-visual integration in the superior colliculus. NEW & NOTEWORTHY This is the first study to systematically explore the interaction of rotational and translational signals in the vestibular nuclei through independent manipulation. The results of this study demonstrate nonlinear integration leading to maximum response amplitude when the timing and direction of peak rotational and translational responses are coincident.

Sign in / Sign up

Export Citation Format

Share Document