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Cuneate nucleus

About: Cuneate nucleus is a research topic. Over the lifetime, 614 publications have been published within this topic receiving 24859 citations. The topic is also known as: cuneate nucleus of spinal cord.


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Journal Article
TL;DR: The present study showed that the primary afferent terminals in the cuneate nucleus of the monkey are mostly large and that they contain round vesicles, commonly found within synaptic complexes in which they are presynaptic to dendrites of various sizes, and are themselves postsynaptic to smaller axon terminals containing flattened vesicle.
Abstract: Six monkeys (Macaca fascicularis) were used for the present study. In animals which survived for 2-6 days after section of C5 to T1 dorsal roots, at least four types of degenerating afferent terminal were observed - electron-dense, electron-lucent, neurofilamentous and flocculent. The electron-dense degeneration was the most common and was seen as early as 2 days after rhizotomy. The neurofilamentous type was the second commonest and was found predominantly in the 3 days' survival material. The electron-lucent and flocculent types were less commonly encountered. Since the profiles exhibiting neurofilamentous hyperplasia showed varying degrees of electron density it is suggested that this type of degeneration progresses to the electron-dense type with time. The present study also showed that the primary afferent terminals in the cuneate nucleus of the monkey are mostly large and that they contain round vesicles. They are commonly found within synaptic complexes in which they are presynaptic to dendrites of various sizes, and are themselves postsynaptic to smaller axon terminals containing flattened vesicles. Degenerating terminals forming isolated synapses were less commonly seen. No dorsal root axon terminals formed axosomatic synapses.

12 citations

Journal Article
TL;DR: It is suggested that the trigemino-neck muscle reflex will be generated monosynaptically by the primary neurons arising from the snout sensory organs and that these primary neurons may play a large role as a neuronal bridge in connecting the masticatory reflex system and the cranio-neck reflex system.
Abstract: To obtain the neuroanatomical information on the role of the snout sensory input in mastication, the present study was conducted on young and adult mice, young Wistar rats and adult Japanese shrew-moles. The animals were subjected to unilateral and bilateral infraorbital nerve transection. Transganglionic degeneration was studied by the Nauta method and electron microscopy including HRP application to the neck muscles. Transganglionic degeneration was found in every experimental case. 1. Transganglionic degeneration of the fibers was found not only in the main sensory nucleus and spinal tract nucleus of the trigeminal nerve but throughout the cervical and the upper part of the thoracic spinal cord. 2. These transganglionically degenerated fibers descended bilaterally through the cuneate nucleus and then caudally through the posterior funiculus at the obex level. They then entered the dorsal and ventral horns to make a synaptic contact with the degenerated synapses on the dorsal horn cells and with the multipolar cells in the ventral horns. This neuroanatomical information suggests: 1) that the trigemino-neck muscle reflex will be generated monosynaptically by the primary neurons arising from the snout sensory organs and 2) that these primary neurons may play a large role as a neuronal bridge in connecting the masticatory reflex system and the cranio-neck reflex system.

12 citations

Journal ArticleDOI
01 Sep 2000-Synapse
TL;DR: A large number of glycine‐IR terminals making direct synaptic contacts with CTNs are shown, suggesting that glycine is one of the important neurotransmitters involved in postsynaptic inhibition on the cuneothalamic relay neurons to modulate incoming somatosensory information from forelimb areas in the rat.
Abstract: This study was aimed to clarify whether the cuneothalamic relay neurons (CTNs) in the rat cuneate nucleus contained glycine or whether the neurons were modulated directly by presynaptic glycine-IR terminals. For this purpose, retrograde transport of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) and immunoperoxidase labelling for glycine have been used to ascertain if the CTNs in the rat are glycine-immunoreactive (glycine-IR). Our results have shown that the WGA-HRP-labelled CTNs (mean area = 318 +/- 6.5 microm(2)) were not reactive for glycine. Glycine immunoreactivity, however, was localized in some small-sized neurons (mean area = 210 +/- 6.2 microm(2)) and axon terminals associated with the CTNs. The synaptic organization between the glycine-IR terminals and CTNs was further analyzed using anti-glycine postembedding immunogold labelling. By electron microscopy, the immunogold-labelled glycine-IR terminals containing pleomorphic synaptic vesicles formed symmetrical synaptic contacts with the dendrites, dendritic spines, and somata of CTNs. Quantitative estimation showed that the mean ratios of glycine-IR terminals to total terminals associated with the soma, proximal dendrites and distal dendrites of the CTN were 49.5, 45.2, and 45.8%, respectively. The higher incidence of glycine-IR terminals on the soma, however, was not significantly different from that of the proximal and distal dendrites. Notwithstanding the above, this study has shown a large number of glycine-IR terminals making direct synaptic contacts with CTNs, suggesting that glycine is one of the important neurotransmitters involved in postsynaptic inhibition on the cuneothalamic relay neurons to modulate incoming somatosensory information from forelimb areas in the rat.

12 citations

Journal ArticleDOI
TL;DR: It was demonstrated that diazepam inhibited the spontaneously firing neurons in the cuneate nucleus, also inhibited by GABA, as well as the concurrent iontophoresis of bicuculline or picrotoxin, both known GABA antagonists.

12 citations

Journal ArticleDOI
TL;DR: In rats that sustained forelimb removals at birth or transection of the brachial plexus in adulthood, dense galanin immunoreactivity was present throughout the cuneate nucleus at all rostrocaudal levels on the side of the brainstem ipsilateral to the lesion.
Abstract: Rats that sustained forelimb removal on either embryonic day (E) 16, on the day of birth (P-0), or transection of the brachial plexus in adulthood had brainstem sections stained for galanin, calcitonin gene-related peptide (CGRP), or substance P (SP) at various intervals after these lesions were made. In normal adult rats, only a few galanin-immunoreactive fibers are present in the cuneate nucleus and most are located in its caudal portion. CGRP-positive axons are also sparse in the cuneate and are distributed mainly in the periphery of the nucleus. SP-positive axons are seen throughout the cuneate nucleus. In rats that sustained forelimb removals at birth or transection of the brachial plexus in adulthood, dense galanin immunoreactivity was present throughout the cuneate nucleus at all rostrocaudal levels on the side of the brainstem ipsilateral to the lesion. The changes after lesions that were made in the adult animals were apparent within 1 week, the earliest time analyzed. Increases in galanin immunoreactivity in the cuneate of animals that sustained forelimb removals on P-0 were first visible on P-2. Neither forelimb removal at birth nor brachial plexus lesions in adulthood had any qualitative effect upon the distribution or density of CGRP- or SP-immunoreactivity in the cuneate nucleus. Removal of a forelimb on E-16 did not increase the density of galanin-immunoreactive fibers in the cuneate nucleus. Such lesions also failed to produce any appreciable change in the density of either CGRP- or SP-positive fibers in the cuneate nucleus. The present data raise the possibility that large caliber, non-peptidergic primary afferent axons which innervate the cuneate nucleus may express galanin after damage at birth or in adulthood.

12 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
20222
202115
20204
20195
20186