scholarly journals Central and peripheral innervation patterns of defined axial motor units in larval zebrafish

2019 ◽  
Vol 527 (15) ◽  
pp. 2557-2572 ◽  
Author(s):  
Saul Bello‐Rojas ◽  
Ana E. Istrate ◽  
Sandeep Kishore ◽  
David L. McLean
Keyword(s):  
Motor Units ◽  
Larval Zebrafish ◽  
Peripheral Innervation ◽  
Innervation Patterns

scholarly journals Central and peripheral innervation patterns of defined axial motor units in larval zebrafish

2019 ◽  
Author(s):  
Saul Bello-Rojas ◽  
Ana E. Istrate ◽  
Sandeep Kishore ◽  
David L. McLean
Keyword(s):  
Motor Neurons ◽  
Muscle Fibers ◽  
Motor Units ◽  
Spinal Motor Neurons ◽  
Larval Zebrafish ◽  
Spinal Motor ◽  
Axon Collaterals ◽  
Peripheral Innervation ◽  
Innervation Patterns ◽  
Fast Twitch

AbstractSpinal motor neurons and the peripheral muscle fibers they innervate form discrete motor units that execute movements of varying force and speed. Subsets of spinal motor neurons also exhibit axon collaterals that influence motor output centrally. Here, we have used in vivo imaging to anatomically characterize the central and peripheral innervation patterns of axial motor units in larval zebrafish. Using early born ‘primary’ motor neurons and their division of epaxial and hypaxial muscle into four distinct quadrants as a reference, we define three distinct types of later born ‘secondary’ motor units. The largest are ‘m-type’ units, which innervate deeper fast-twitch muscle fibers via medial nerves. Next in size are ‘ms-type’ secondaries, which innervate superficial fast-twitch and slow fibers via medial and septal nerves, followed by ‘s-type’ units, which exclusively innervate superficial slow muscle fibers via septal nerves. All types of secondaries innervate up to four axial quadrants. Central axon collaterals are found in subsets of primaries based on soma position and predominantly in secondary fast-twitch units (m, ms) with increasing likelihood based on number of quadrants innervated. Collaterals are labeled by synaptophysin-tagged fluorescent proteins, but not PSD95, consistent with their output function. Also, PSD95 dendrite labeling reveals that larger motor units receive more excitatory synaptic input. Collaterals are largely restricted to the neuropil, however perisomatic connections are observed between motor units. These observations suggest that recurrent interactions are dominated by motor neurons recruited during stronger movements and set the stage for functional investigations of recurrent motor circuitry in larval zebrafish.

scholarly journals Abnormal Reinnervation of Denervated Areas Following Nerve Injury Facilitates Neuropathic Pain

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 1007 ◽  
Author(s):  
Hodaya Leibovich ◽  
Nahum Buzaglo ◽  
Shlomo Tsuriel ◽  
Liat Peretz ◽  
Yaki Caspi ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Nerve Injury ◽  
Peripheral Nerves ◽  
Dorsal Root ◽  
Pain Sensitivity ◽  
Spared Nerve Injury ◽  
Drg Neurons ◽  
Nociceptive Neurons ◽  
Peripheral Innervation ◽  
Innervation Patterns

An injury to peripheral nerves leads to skin denervation, which often is followed by increased pain sensitivity of the denervated areas and the development of neuropathic pain. Changes in innervation patterns during the reinnervation process of the denervated skin could contribute to the development of neuropathic pain. Here, we examined the changes in the innervation pattern during reinnervation and correlated them with the symptoms of neuropathic pain. Using a multispectral labeling technique—PainBow, which we developed, we characterized dorsal root ganglion (DRG) neurons innervating distinct areas of the rats’ paw. We then used spared nerve injury, causing partial denervation of the paw, and examined the changes in innervation patterns of the denervated areas during the development of allodynia and hyperalgesia. We found that, differently from normal conditions, during the development of neuropathic pain, these areas were mainly innervated by large, non-nociceptive neurons. Moreover, we found that the development of neuropathic pain is correlated with an overall decrease in the number of DRG neurons innervating these areas. Importantly, treatment with ouabain facilitated reinnervation and alleviated neuropathic pain. Our results suggest that local changes in peripheral innervation following denervation contribute to neuropathic pain development. The reversal of these changes decreases neuropathic pain.

The vestibular nerve of the chinchilla. V. Relation between afferent discharge properties and peripheral innervation patterns in the utricular macula

1990 ◽  
Vol 63 (4) ◽  
pp. 791-804 ◽  
Author(s):  
J. M. Goldberg ◽  
G. Desmadryl ◽  
R. A. Baird ◽  
C. Fernandez
Keyword(s):  
Lucifer Yellow ◽  
Small Diameter ◽  
Sampling Bias ◽  
Vestibular Nerve ◽  
Strongly Correlated ◽  
Utricular Macula ◽  
Peripheral Innervation ◽  
Physiological Properties ◽  
Innervation Patterns ◽  
Discharge Patterns

1. The relation between the discharge properties of utricular afferents and their peripheral innervation patterns was studied in the chinchilla by the use of intra-axonal labeling techniques. Fifty-three physiologically characterized units were injected with horseradish peroxidase (HRP) or lucifer yellow CH (LY) and their labeled processes were traced to the utricular macula. For most labeled neurons, the discharge regularity, background discharge, and sensitivity to externally applied galvanic currents were determined, as were the gain (g2 Hz) and phase (phi 2 Hz) of the response to 2-Hz sinusoidal linear forces. Terminal fields were reconstructed and fibers were classified as calyx (n = 13) or dimorphic units (n = 40). No bouton units were recovered. Calyx units were confined to the striola. Dimorphic units were located in the striola (n = 8), the juxtastriola (n = 7), or the peripheral extrastriola (n = 25). 2. To determine whether the intra-axonal sample was representative, the physiological properties of labeled utricular units were compared with those of a larger sample of extracellularly recorded units. A comparison was also made between the morphology of intra-axonally labeled units and those labeled by the extracellular injection of HRP into the vestibular nerve. Most of the discrepancies between the intra-axonal and either extracellular sample can be explained by assuming that small-diameter fibers are underrepresented in the former sample. Dimorphic fibers labeled intra-axonally had more bouton endings and larger terminal trees than did those labeled extracellularly. The latter differences may reflect a sampling bias in the extracellular material. 3. Calyx units were irregularly discharging. The discharge regularity of dimorphic units was related to their macular locations. Only 1/8 dimorphic units in the striola was regularly discharging. The ratio increases to 3/7 in the juxtastriola and to 23/25 in the peripheral extrastriola. Among dimorphic units, there is a tendency for irregularly discharging afferents to have fewer bouton endings. The trend is far from perfect because it is possible to pick a subsample of dimorphic units that have similar numbers of boutons and, yet, have discharge patterns that range from regular to irregular. 4. Published morphological polarization maps can be used to predict the excitatory tilt directions of a unit from its macular location. Predictions were confirmed in 39/41 labeled afferents. 5. The galvanic sensitivity (beta *) of an afferent, irrespective of its peripheral innervation pattern or its epithelial location, was strongly correlated with a normalized coefficient of variation (CV*).(ABSTRACT TRUNCATED AT 400 WORDS)

The vestibular nerve of the chinchilla. II. Relation between afferent response properties and peripheral innervation patterns in the semicircular canals

1988 ◽  
Vol 60 (1) ◽  
pp. 182-203 ◽  
Author(s):  
R. A. Baird ◽  
G. Desmadryl ◽  
C. Fernandez ◽  
J. M. Goldberg
Keyword(s):  
Lucifer Yellow ◽  
Discharge Rate ◽  
Small Diameter ◽  
Semicircular Canals ◽  
Preceding Paper ◽  
Vestibular Nerve ◽  
Response Properties ◽  
Peripheral Innervation ◽  
Innervation Patterns ◽  
The One

1. The relation between the response properties of semicircular canal afferents and their peripheral innervation patterns was studied by the use of intra-axonal labeling techniques. Fifty physiologically characterized units were injected with horseradish peroxidase (HRP) or Lucifer yellow CH (LY) and their processes were traced to the crista. The resting discharge, discharge regularity, and responses to both externally applied galvanic currents and sinusoidal head rotations were determined for most neurons. Terminal fields were reconstructed and, as in the preceding paper, the fibers were classified as calyx, bouton, or dimorphic units. 2. To determine if the intra-axonal sample was representative, the physiological properties of the labeled units were compared with those of a sample of extracellularly recorded units. A comparison was also made between the morphology of the intra-axonal units and those labeled by extracellular injection of HRP into the vestibular nerve Most of the discrepancies between the intra-axonal and the two extracellular samples can be explained by assuming that small-diameter fibers are underrepresented in the former sample. 3. A normalized coefficient of variation (CV*), independent of discharge rate, was used to classify units as regular, intermediate, or irregular. The CV* ranged from 0.020 to 0.60. Regular units (CV* less than or equal to 0.10) outnumbered irregular units (CV* greater than or equal to 0.20) by an approximately 3:1 ratio and had higher resting discharges. 4. Calyx units were invariably irregular. The one recovered bouton unit was regular. The discharge regularity of dimorphic units was related to their epithelial location, with those found in the periphery of the crista having a more regular discharge than those located more centrally. Dimorphic units, even those with quite similar morphology, can differ in their discharge regularity. Calyx and dimorphic units, which differ in their morphology, can both be irregular. These observations imply that discharge regularity is not determined by the branching pattern of a fiber or the number and types of hair cells it contacts. 5. The galvanic sensitivity (beta*) of an afferent, irrespective of its peripheral innervation pattern, was strongly correlated with CV*. This is consistent with the notion that discharge regularity and galvanic sensitivity are causally related, both being determined by postspike recovery mechanisms of the afferent nerve terminal.(ABSTRACT TRUNCATED AT 400 WORDS)

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