Differential origin of reticulospinal drive to motoneurons innervating trunk and hindlimb muscles in the mouse revealed by optical recording

Szokol, Karolina; Glover, Joel C.; Perreault, Marie−Claude

doi:10.1113/jphysiol.2008.158105

Cited by 28 publications

(61 citation statements)

References 69 publications

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“…To account for differences in labeling intensity among different MNs/dCINs, the Ca 2ϩ transients in each ROI were expressed as changes in fluorescence intensity divided by the prestimulus baseline intensity [⌬F/F ϭ (F Ϫ F baseline )/F baseline ]. We have previously evaluated the extent to which light scattering from an (Szokol et al, 2008;). A2, B2, Corresponding graphs showing the magnitudes of the responses during mephenesin application, normalized to the control response.…”

Section: Methodsmentioning

confidence: 99%

“…In a series of control experiments, we tested whether the most effective stimulation parameters for evoking reticulospinal responses in lumbar MNs (Szokol et al, 2008;) also effectively evoked responses in dCINs. This was done by stimulating the medial and lateral regions of the ipsilateral MRF with various train durations and frequencies (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The effective sites in the medial and lateral MRF regions are plotted as filled and unfilled squares, respectively. Cross-hatched areas indicate the regions that were previously found to be effective in evoking responses in the MMC and LMC (Szokol et al, 2008). 5N, Spinal trigeminal nucleus; 7N, facial nucleus; 10N, dorsal motor nucleus of the vagus; 12N, hypoglossal nucleus; Amb, ambiguus nucleus; DPGi, dorsal paragigantocellularis nucleus; Gi, gigantocellularis reticular nucleus; Gi␣, pars ␣; Giv, pars ventralis; IO, inferior olive nucleus; LPGi, lateral paragigantocellularis nucleus; LVe, lateral vestibular nucleus; LR, lateral reticular nucleus; iRt, intermediate reticular nucleus; MVe, medial vestibular nucleus; Pyr, pyramidal tract; RbS, rubrospinal tract; Rm, raphe nucleus magnus; Ro, raphe nucleus obscurus; Rp, raphe nucleus pallidus; SpVe, spinal vestibular nucleus.…”

Section: Effect Of Mephenesin and Midline Lesions On Mrf-evoked Respomentioning

confidence: 99%

“…The stimulating electrode was targeted to the same two regions of the MRF, which we previously denoted "medial MRF" and "lateral MRF" and which exert differential effects on MNs of the medial and lateral motor columns (MMC and LMC, respectively) in L2 and L5 segments (Szokol et al, 2008;). Mephenesin was bath-applied to the spinal cord after isolating it from the brainstem with a vaseline barrier made at C1 (n ϭ 6).…”

Section: Effect Of Mephenesin and Midline Lesions On Mrf-evoked Respomentioning

confidence: 99%

“…Here, we use a recently developed calcium-imaging approach to assess synaptic connections between brainstem and spinal neurons in the neonatal mouse (Szokol et al, 2008;) to determine whether lumbar CINs receive inputs from medullary reticulospinal neurons. In the neonatal rodent, four classes of CINs can be identified on the basis of contralateral axonal trajectory: intrasegmental (short-range CINs), intersegmental ascending, descending (aCINs, dCINs), and bifurcating [ascending, descending (adCINs)] (Eide et al, 1999;Stokke et al, 2002;Nissen et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Organization of Functional Synaptic Connections between Medullary Reticulospinal Neurons and Lumbar Descending Commissural Interneurons in the Neonatal Mouse

Szokol¹,

Glover²,

Perreault³

2011

J. Neurosci.

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The medullary reticular formation (MRF) of the neonatal mouse is organized so that the medial and lateral MRF activate hindlimb and trunk motoneurons (MNs) with differential predominance. The goal of the present study was to investigate whether this activation is polysynaptic and mediated by commissural interneurons with descending axons (dCINs) in the lumbar spinal cord. To this end, we tested the polysynapticity of inputs from the MRF to MNs and tested for the presence of selective inputs from medial and lateral MRF to 574 individual dCINs in the L2 segment of the neonatal mouse.Reticulospinal-mediated postsynaptic Ca 2ϩ responses in MNs were reduced in the presence of mephenesin and after a midline lesion, suggesting the involvement of dCINs in mediating the responses. Consistent with this, stimulation of reticulospinal neurons in the medial or lateral MRF activated 51% and 57% of ipsilateral dCINs examined (255 and 352 dCINs, respectively) and 52% and 46% of contralateral dCINs examined (166 and 133 dCINs, respectively). The proportion of dCINs that responded specifically to stimulation of medial or lateral MRF was similar to the proportions of dCINs that responded to both MRF regions or to neither. The three responsive dCIN populations had largely overlapping spatial distributions.We demonstrate the existence of dCIN subpopulations sufficient to mediate responses in lumbar motoneurons from reticulospinal pathways originating from the medial and lateral MRF. Differential control of trunk and hindlimb muscles by the medullary reticulospinal system may therefore be mediated in part by identifiable dCIN populations.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Effect Of Mephenesin and Midline Lesions On Mrf-evoked Respomentioning

confidence: 99%

Section: Effect Of Mephenesin and Midline Lesions On Mrf-evoked Respomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Organization of Functional Synaptic Connections between Medullary Reticulospinal Neurons and Lumbar Descending Commissural Interneurons in the Neonatal Mouse

Szokol¹,

Glover²,

Perreault³

2011

J. Neurosci.

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Cellular reactions and compensatory tissue re‐organization during spontaneous recovery after spinal cord injury in neonatal mice

Chawla

Züchner

Mastrangelopoulou

et al. 2017

Developmental Neurobiology

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Following incomplete spinal cord injuries, neonatal mammals display a remarkable degree of behavioral recovery. Previously, we have demonstrated in neonatal mice a wholesale re-establishment and reorganization of synaptic connections from some descending axon tracts (Boulland et al.: PLoS One 8 (2013)). To assess the potential cellular mechanisms contributing to this recovery, we have here characterized a variety of cellular sequelae following thoracic compression injuries, focusing particularly on cell loss and proliferation, inflammation and reactive gliosis, and the dynamics of specific types of synaptic terminals. Early during the period of recovery, regressive events dominated. Tissue loss near the injury was severe, with about 80% loss of neurons and a similar loss of axons that later make up the white matter. There was no sign of neurogenesis, no substantial astroglial or microglial proliferation, no change in the ratio of M1 and M2 microglia and no appreciable generation of the terminal complement peptide C5a. One day after injury the number of synaptic terminals on lumbar motoneurons had dropped by a factor of 2, but normalized by 6 days. The ratio of VGLUT1/2+ to VGAT+ terminals remained similar in injured and uninjured spinal cords during this period. By 24 days after injury, when functional recovery is nearly complete, the density of 5-HT+ fibers below the injury site had increased by a factor of 2.5. Altogether this study shows that cellular reactions are diverse and dynamic. Pronounced recovery of both excitatory and inhibitory terminals and an increase in serotonergic innervation below the injury, coupled with a general lack of inflammation and reactive gliosis, are likely to contribute to the recovery. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 928-946, 2017.

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Zebrafish Erc1b mediates motor innervation and organization of craniofacial muscles in control of jaw movement

Luderman

Michaels

Levic

et al. 2022

Developmental Dynamics

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Background: Movement of the lower jaw, a common behavior observed among vertebrates, is required for eating and processing food. This movement is controlled by signals sent from the trigeminal motor nerve through neuromuscular junctions (NMJs) to the masticatory muscles. Dysfunctional jaw movements contribute to craniomandibular disorders, yet the pathophysiology of these disorders is not well understood, as limited studies have been conducted on the molecular mechanisms of jaw movement.Results: Using erc1b/kim m533 genetic loss of function mutant, we evaluated lower jaw muscle organization and innervation by the cranial motor nerves in developing zebrafish. Using time-lapse confocal imaging of the erc1b mutant in a transgenic fluorescent reporter line, we found delayed trigeminal nerve growth and disrupted nerve branching architecture during muscle innervation.

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Differential origin of reticulospinal drive to motoneurons innervating trunk and hindlimb muscles in the mouse revealed by optical recording

Cited by 28 publications

References 69 publications

Organization of Functional Synaptic Connections between Medullary Reticulospinal Neurons and Lumbar Descending Commissural Interneurons in the Neonatal Mouse

Organization of Functional Synaptic Connections between Medullary Reticulospinal Neurons and Lumbar Descending Commissural Interneurons in the Neonatal Mouse

Cellular reactions and compensatory tissue re‐organization during spontaneous recovery after spinal cord injury in neonatal mice

Zebrafish Erc1b mediates motor innervation and organization of craniofacial muscles in control of jaw movement

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