Innervation of multiple neck motor nuclei by single reticulospinal tract axons receiving tectal input in the upper cervical spinal cord

Kakei, Shinji; Muto, Naoko; Shinoda, Yoshikazu

doi:10.1016/0304-3940(94)90668-8

Cited by 28 publications

(12 citation statements)

References 15 publications

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“…Although there is both behavioral and physiological evidences that suggest that the SCs functionally suppress each other by commissural connections, little is known about the existence of an excitatory commissural connection and its functional role. Most of the TRNs examined projected to both the FFH and the IBN region, where interstitiospinal (Isa and Sasaki 1992) and reticulospinal neurons (Kakei et al 1994) terminating on neck motoneurons are located. Furthermore, some of these TRNs may be tectospinal neurons with a collateral projection to the IBN region (Grantyn and Grantyn 1982;Muto et al 1996;Shinoda et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Commissural Mirror-Symmetric Excitation and Reciprocal Inhibition Between the Two Superior Colliculi and Their Roles in Vertical and Horizontal Eye Movements

Takahashi

Sugiuchi²,

Shinoda³

2007

Journal of Neurophysiology

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The functional roles of commissural excitation and inhibition between the two superior colliculi (SCs) are not yet well understood. We previously showed the existence of strong excitatory commissural connections between the rostral SCs, although commissural connections had been considered to be mainly inhibitory. In this study, by recording intracellular potentials, we examined the topographical distribution of commissural monosynaptic excitation and inhibition from the contralateral medial and lateral SC to tectoreticular neurons (TRNs) in the medial or lateral SC of anesthetized cats. About 85% of TRNs examined projected to both the ipsilateral Forel's field H and the contralateral inhibitory burst neuron region where the respective premotor neurons for vertical and horizontal saccades reside. Medial TRNs received strong commissural excitation from the medial part of the opposite SC, whereas lateral TRNs received excitation mainly from its lateral part. Injection of wheat germ agglutinin-horseradish peroxidase into the lateral or medial SC retrogradely labeled many larger neurons in the lateral or medial part of the contralateral SC, respectively. These results indicated that excitatory commissural connections exist between the medial and medial parts and between the lateral and lateral parts of the rostral SCs. These may play an important role in reinforcing the conjugacy of upward and downward saccades, respectively. In contrast, medial SC projections to lateral SC TRNs and lateral SC projections to medial TRNs mainly produce strong inhibition. This shows that regions representing upward saccades inhibit contralateral regions representing downward saccades and vice versa.

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Section: Discussionmentioning

confidence: 99%

Commissural Mirror-Symmetric Excitation and Reciprocal Inhibition Between the Two Superior Colliculi and Their Roles in Vertical and Horizontal Eye Movements

Takahashi

Sugiuchi²,

Shinoda³

2007

Journal of Neurophysiology

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“…For example, we now know that sub-populations of raphe-, vestibulo-, rubro-and reticulospinal neurons have axons or collaterals that terminate in both the cervical and lumbar spinal enlargements (Wolstencroft, 1964;Abzug et al, 1974Abzug et al, , 1973Peterson et al, 1975;Huisman et al, 1981;Manaker et al, 1992) and that many of the reticulospinal neurons innervating both enlargements do so at multiple cervical and lumbar segmental levels (Takakusaki et al, 1994;Kakei et al, 1994). In addition, Giovanelli Barilari and Kuypers (1969) compared the terminal distributions of long propriospinal fibers interconnecting the enlargements with those of various descending supraspinal pathways and found substantial overlap with reticulospinal fibers along with a significant but more varied overlap with terminals of vestibulo-, tecto-, and interstitiospinal fibers.…”

Section: Discussionmentioning

confidence: 99%

Reticulospinal pathways in the ventrolateral funiculus with terminations in the cervical and lumbar enlargements of the adult rat spinal cord

2008

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In the mammalian spinal cord, the ventrolateral funiculus (VLF) has been identified as critical to postural control and locomotor function, in part due to the reticulospinal pathways it contains. The primary purpose of this descriptive study was to investigate the distribution of neurons in the medulla labeled retrogradely from the VLF and the intermediate gray matter of specific lumbar and cervical spinal cord segments in the adult rat.We made discrete injections of Fluoro-Ruby (FR) into the intermediate gray matter at the cervical (C) 5/6, 7/8 or lumbar (L) 2 segmental levels followed by a single injection of Fluoro-Gold (FG) into the right VLF at T9. Double-labeled medullary neurons were found primarily in the gigantocellular group of nuclei (Gi), distributed both ipsilaterally and contralaterally following cervical or lumbar FR injections. In addition, a substantial population of neurons contained within the vestibular group of nuclei was double labeled both ipsilaterally and contralaterally. We also identified a substantial population of Gi-related neurons located ipsilateral to the VLF injections that were double labeled following left unilateral FR injections at C5/6, C7/8 or L2.These results describe a substantial population of ipsilateral and commissural medullary neurons that project to both cervical and thoracolumbar segments. Two different populations of commissural neurons are described, one with axons that cross the midline rostral to T9, and one with axons that cross the midline caudal to T9. These observations provide strong additional evidence for a pattern of reticulo-and vestibulospinal projections that include substantial numbers of commissural neurons and project to multiple cervical and thoracolumbar levels.

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“…Electrical stimulation of the paramedian portion of the gigantocellular MdRF between the levels of the abducens and hypoglossal nuclei produces head movements like those seen with gaze changes (Iwamoto et al,1988; Drew and Rossignol,1990a,b; Cowie et al,1994; Cowie and Robinson,1994; Quessy and Freedman,2004). This region contains reticulospinal neurons that receive collicular inputs and fire before head movements in conjunction with gaze changes (Kakei et al,1994; Isa and Naito, 1995).…”

Section: Introductionmentioning

confidence: 99%

The Mesencephalic Reticular Formation as a Conduit for Primate Collicular Gaze Control: Tectal Inputs to Neurons Targeting the Spinal Cord and Medulla

Perkins

Warren

May

2009

The Anatomical Record

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The superior colliculus (SC), which directs orienting movements of both the eyes and head, is reciprocally connected to the mesencephalic reticular formation (MRF), suggesting the latter is involved in gaze control. The MRF has been provisionally subdivided to include a rostral portion, which subserves vertical gaze, and a caudal portion, which subserves horizontal gaze. Both regions contain cells projecting downstream that may provide a conduit for tectal signals targeting the gaze control centers which direct head movements. We determined the distribution of cells targeting the cervical spinal cord and rostral medullary reticular formation (MdRF), and investigated whether these MRF neurons receive input from the SC by the use of dual tracer techniques in Macaca fascicularis monkeys. Either biotinylated dextran amine or Phaseolus vulgaris leucoagglutinin was injected into the SC. Wheat germ agglutinin conjugated horseradish peroxidase was placed into the ipsilateral cervical spinal cord or medial MdRF to retrogradely label MRF neurons. A small number of medially located cells in the rostral and caudal MRF were labeled following spinal cord injections, and greater numbers were labeled in the same region following MdRF injections. In both cases, anterogradely labeled tectoreticular terminals were observed in close association with retrogradely labeled neurons. These close associations between tectoreticular terminals and neurons with descending projections suggest the presence of a trans-MRF pathway that provides a conduit for

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Innervation of multiple neck motor nuclei by single reticulospinal tract axons receiving tectal input in the upper cervical spinal cord

Cited by 28 publications

References 15 publications

Commissural Mirror-Symmetric Excitation and Reciprocal Inhibition Between the Two Superior Colliculi and Their Roles in Vertical and Horizontal Eye Movements

Commissural Mirror-Symmetric Excitation and Reciprocal Inhibition Between the Two Superior Colliculi and Their Roles in Vertical and Horizontal Eye Movements

Reticulospinal pathways in the ventrolateral funiculus with terminations in the cervical and lumbar enlargements of the adult rat spinal cord

The Mesencephalic Reticular Formation as a Conduit for Primate Collicular Gaze Control: Tectal Inputs to Neurons Targeting the Spinal Cord and Medulla

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