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.

Organization of diencephalic projections from the medullary subnucleus reticularis dorsalis and the adjacent cuneate nucleus: a retrograde and anterograde tracer study in the rat.

Abstract: The distribution and organization of diencephalic projections from the subnucleus reticularis dorsalis (SRD) and the neighbouring cuneate nucleus (Cu) were studied in the rat by using microinjections of Phaseolus vulgaris leucoagglutinin in SRD and Cu and wheat germ agglutinin-apo horseradish peroxidase-gold in some selected thalamic areas. As previously reported, the efferent projections from the Cu were essentially contralateral and terminated mainly in the ventroposterolateral thalamic nucleus. Less dense terminals from the Cu were also observed in the posterior thalamic group, the ventral aspect of the zona incerta and the caudal and dorsal portion of the reuniens area. Retrograde tracer injections in the medial ventroposterolateral thalamic nucleus labeled numerous cells in the contralateral Cu, with a smaller number in the gracile nucleus. From the SRD, terminals were observed in the lateral aspect of the ventromedial thalamic nucleus, the lateral parafascicular area and, to a lesser extent, in the ventral aspect of the zona incerta and the core of the reuniens area. Retrograde tracer injections in the lateral part of the ventromedial thalamic nucleus labeled cells in the caudal medulla, many of which were located in the dorsal-most aspect of the SRD throughout its caudo-rostral extent. The existence of SRD-thalamic connections reinforces the idea that the caudal reticular formation is an important nociceptive relay to the thalamus. Our data shed new light on old hypotheses suggesting that, in addition to spino-thalamic pathways, spino-reticulo-thalamic pathways may play an important role in distributing pain signals to the forebrain.

Projection systems and terminal localization of dorsal column afferents: An autoradiographic and horseradish peroxidase study in the rat

Abstract: Projection systems from the gracile nucleus and the cuneate nuclear complex to their terminal sites in the mesencephalon, diencephalon, and cerebellum were examined by means of anterograde autoradiography and retrograde horseradish peroxidase methods. Three projection systems emerge from the dorsal column nuclei, decussate via internal arcuate fibers, and form the contralateral medial lemniscus (ML). At the obex, some fibers split off the ML and course dorsolaterally, forming an ascending lateral system which fits the “lemniscal adjunct channel” (LAC) concept of Graybiel ('72). The ML continues rostrally as the “main lemniscal line channel” (MLLC). At the inferior colliculus, some LAC fibers terminate in the pontine nuclei, parabrachial, dorsal reticular nuclei, and the external and ventral medial part of the central nucleus of the inferior colliculus. More rostrally at the level of the superior colliculus, terminal fields are found in the medial nucleus of the medial geniculate body, the suprageniculate, pretectal, and mesencephalic reticular nuclei, marking the end of the LAC. In the diencephalon, gracile fibers leave the MLLC and form a crescentlike terminal field along the extreme lateral border of the ventral posterior lateral nucleus (VPL) of the thalamus. Cuneate MLLC fibers terminate in a bandlike formation in the VPL medial to the gracile termination. The third fiber system, the cuneocerebellar projection, emerges from the cuneate, the external cuneate nuclei, and the “cellular bridge” and immediately enters the ipsilateral inferior cerebellar peduncle. Upon entering the cerebellum, the major fiber component remains ipsilateral and terminates as vertical bands in vermal and paravermal lobules, and lobules I through IVa. The posterior cerebellar lobe contains terminal bands in lobules VII–IX, the copula pyramidis, and the paramedian lobule. It is concluded that the dorsolateral fiber system conforms to Graybiel's LAC. It is more divergent and probably less modality specific, whereas the medial lemniscal system conforms to the MLLC, which is said to be modality specific, less divergent, and locked to specific sensory-motor response characteristics. The topography of cerebellar terminal bands indicates that there is sensory-motor representation from all parts of the body to all parts of the cerebellum, at least in the rat.