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Connections of the superior colliculus to shoulder muscles of the rat: a dual tracing study.

Rubelowski JM, Menge M, Distler C, Rothermel M, Hoffmann KP - Front Neuroanat (2013)

Bottom Line: Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements.Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic.In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus.

View Article: PubMed Central - PubMed

Affiliation: Allgemeine Zoologie and Neurobiologie, Ruhr-University Bochum Bochum, Germany.

ABSTRACT
Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements. In the present study we investigated the tectofugal, in particular the tecto-reticulo-spinal projections to the shoulder and arm muscles in the rat. We simultaneously retrogradely labeled the premotor neurons in the brainstem by injection of the pseudorabies virus PrV Bartha 614 into the m. rhomboideus minor and m. acromiodeltoideus, and anterogradely visualized the tectofugal projections by intracollicular injection of the tracer FITC dextrane. Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic. This was confirmed by long survival times after virus injections into the muscles (98-101 h) after which numerous neurons in the deep layers of the SC were labeled. Transsynaptically retrogradely labeled brainstem neurons connected disynaptically to the injected muscles with adjacent tectal terminals were predominantly located in the gigantocellular nuclear complex of the reticular formation. In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus. Both tectal projections to the nucleus gigantocellularis and the pontine reticular nucleus were bilateral but ipsilaterally biased. We suggest this projection to be involved in more global functions in motivated behavior like general arousal allowing fast voluntary motor activity.

No MeSH data available.


Related in: MedlinePlus

Injection sites into the superficial (A, SC4), the intermediate-deep (B, SC14), and the deep (C, SC13) layers of the superior colliculus. Left panel: reconstructions of the dorsal view of the right SC, middle panel: drawings of frontal sections through the center of the injection sites, right panel: fluorescent photomicrographs of the FITC injection sites. Red outlines in the left and middle row indicate the location of the FITC injections into the SC. a, anterior; p, posterior; l, lateral; m, medial; scale bars indicate 1 mm.
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Figure 7: Injection sites into the superficial (A, SC4), the intermediate-deep (B, SC14), and the deep (C, SC13) layers of the superior colliculus. Left panel: reconstructions of the dorsal view of the right SC, middle panel: drawings of frontal sections through the center of the injection sites, right panel: fluorescent photomicrographs of the FITC injection sites. Red outlines in the left and middle row indicate the location of the FITC injections into the SC. a, anterior; p, posterior; l, lateral; m, medial; scale bars indicate 1 mm.

Mentions: For the dual tracer experiments we chose survival times of 73–79 h after which no or only few retrogradely labeled neurons were observed in the SC in our initial experiments (see above) indicating that with these survival times the first tectofugal synapse was not overcome by the retrograde propagation of the virus. In this set of experiments we inoculated both the m. rhomboideus and/or the m. acromiodeltoideus (Table 1). Figure 6 demonstrates examples of premotor neurons retrogradely labeled by virus inoculation of m. rhomboideus and m. acromiodeltoideus. In close neighborhood of these neurons fibers and varicosities anterogradely labeled from the SC can be discerned. In the various cases FITC dextrane was injected at different depths in the SC (Figure 7; Table 1).


Connections of the superior colliculus to shoulder muscles of the rat: a dual tracing study.

Rubelowski JM, Menge M, Distler C, Rothermel M, Hoffmann KP - Front Neuroanat (2013)

Injection sites into the superficial (A, SC4), the intermediate-deep (B, SC14), and the deep (C, SC13) layers of the superior colliculus. Left panel: reconstructions of the dorsal view of the right SC, middle panel: drawings of frontal sections through the center of the injection sites, right panel: fluorescent photomicrographs of the FITC injection sites. Red outlines in the left and middle row indicate the location of the FITC injections into the SC. a, anterior; p, posterior; l, lateral; m, medial; scale bars indicate 1 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675767&req=5

Figure 7: Injection sites into the superficial (A, SC4), the intermediate-deep (B, SC14), and the deep (C, SC13) layers of the superior colliculus. Left panel: reconstructions of the dorsal view of the right SC, middle panel: drawings of frontal sections through the center of the injection sites, right panel: fluorescent photomicrographs of the FITC injection sites. Red outlines in the left and middle row indicate the location of the FITC injections into the SC. a, anterior; p, posterior; l, lateral; m, medial; scale bars indicate 1 mm.
Mentions: For the dual tracer experiments we chose survival times of 73–79 h after which no or only few retrogradely labeled neurons were observed in the SC in our initial experiments (see above) indicating that with these survival times the first tectofugal synapse was not overcome by the retrograde propagation of the virus. In this set of experiments we inoculated both the m. rhomboideus and/or the m. acromiodeltoideus (Table 1). Figure 6 demonstrates examples of premotor neurons retrogradely labeled by virus inoculation of m. rhomboideus and m. acromiodeltoideus. In close neighborhood of these neurons fibers and varicosities anterogradely labeled from the SC can be discerned. In the various cases FITC dextrane was injected at different depths in the SC (Figure 7; Table 1).

Bottom Line: Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements.Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic.In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus.

View Article: PubMed Central - PubMed

Affiliation: Allgemeine Zoologie and Neurobiologie, Ruhr-University Bochum Bochum, Germany.

ABSTRACT
Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements. In the present study we investigated the tectofugal, in particular the tecto-reticulo-spinal projections to the shoulder and arm muscles in the rat. We simultaneously retrogradely labeled the premotor neurons in the brainstem by injection of the pseudorabies virus PrV Bartha 614 into the m. rhomboideus minor and m. acromiodeltoideus, and anterogradely visualized the tectofugal projections by intracollicular injection of the tracer FITC dextrane. Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic. This was confirmed by long survival times after virus injections into the muscles (98-101 h) after which numerous neurons in the deep layers of the SC were labeled. Transsynaptically retrogradely labeled brainstem neurons connected disynaptically to the injected muscles with adjacent tectal terminals were predominantly located in the gigantocellular nuclear complex of the reticular formation. In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus. Both tectal projections to the nucleus gigantocellularis and the pontine reticular nucleus were bilateral but ipsilaterally biased. We suggest this projection to be involved in more global functions in motivated behavior like general arousal allowing fast voluntary motor activity.

No MeSH data available.


Related in: MedlinePlus