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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 ArticleDOI
TL;DR: Motoneurons of the nerve were densely labeled by B‐HRP, including extensive regions of their dendritic trees, and the small population of labeled myelinated afferents mainly fell within the smaller ranges than within the larger ranges.
Abstract: The central projections of the rat sciatic, saphenous, median, and ulnar nerves were labeled by injecting each nerve with 0.05 mg B-HRP, or 0.5 mg WGA-HRP, or a mixture of both. The B-HRP labeled large dorsal root ganglion cells (30-50 microns) and, correspondingly, 98% of axons labeled in a rootlet were meyelinated; although all sizes of myelinated axons were labeled, a greater proportion fell in the large ranges (2-6.5 microns axon diameter) than in the small ranges (0.5-2 microns). Primary afferents labeled with B-HRP were distributed in laminae I, III, IV, and V of the dorsal horn and extended into the intermediate grey and the ventral horn; Clarke's column and the respective dorsal column nuclei were also densely labeled. Motoneurons of the nerve were densely labeled by B-HRP, including extensive regions of their dendritic trees. In contrast, WGA-HRP labeled small dorsal root ganglion cells (15-25 microns) and in the dorsal rootlets, 84% of the labeled axons were nonmyelinated; the small population of labeled myelinated afferents mainly fell within the smaller ranges (0.5-2.0 microns). Terminal fields of WGA-HRP labeled afferents were restricted to the superficial dorsal horn (laminae I-III), and to limited regions in the dorsal column nuclei. Sciatic nerve projections traced by labeling with B-HRP alone or in combination with WGA-HRP were more extensive than previously described when using either native HRP or WGA-HRP. Afferents to the dorsal horn extended from L1-S1, to Clarke's nucleus from T8-L1, to the ventral horn from L2-L5, and extended throughout the medial and dorsal region of the gracilie nucleus. Motoneurons were found from L4-L6. Using the same tracers, saphenous projections extended in the superficial dorsal horn from caudal L1 to rostral L4, in the deep dorsal horn to mid L4 and along the length of the central part of the gracilie nucleus. The median nerve projected to the internal basilar nucleus from C1-C6, the dorsal horn from C3-T2, Clarke's nucleus from T1-T6, the external cuneate nucleus, and a large central area throughout the length of the cuneate nucleus. Motoneurons were located in dorsolateral and ventrolateral nuclear groups from C4 through C8. The ulnar nerve projections were less extensive but also included the internal basilar nucleus from C1-C6, the medial region of the dorsal horn from C4-T1, Clarke's nucleus from T1-T6, the external cuneate nucleus, and the medial part of the cuneate nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

233 citations

Journal ArticleDOI
TL;DR: Cuneate cells in anaesthetized cats were strongly excited by L‐glutamate, and somewhat less by D‐ glutamate; cells which receive afferents from hair receptors were particularly sensitive.
Abstract: 1. Cuneate cells in anaesthetized cats were strongly excited by L-glutamate, and somewhat less by D-glutamate; cells which receive afferents from hair receptors were particularly sensitive. 2. Glutamate could be used to demonstrate post-synaptic inhibitory inputs from the dorsal column, the medial lemniscus and the frontal cortex. 3. Many cuneate cells were also strongly excited by adenosinetriphosphate (ATP); this was probably due to the chelating action of ATP, as citric acid was also quite effective. 4. γ-Aminobutyric acid (GABA) readily blocked all forms of spontaneous and evoked activity, except antidromic invasion of cuneothalamic neurones; cells which receive proprioceptive afferents were particularly sensitive to GABA. Glycine had a comparable effect. 5. Acetylcholine (ACh), catecholamines, histamine, 5-hydroxytryptamine (5-HT) and an extract containing substance P mostly had only weak depressant actions. Cholinergic and mono-aminergic mechanisms are probably not very significant in the cuneate. 6. These results are consistent with the possibility that glutamate and GABA (or glycine), or some closely related compounds, are the main excitatory and inhibitory transmitters in the cuneate nucleus. 7. If ATP is released from afferent nerve endings, it could also play a significant role in excitation.

225 citations

Journal ArticleDOI
TL;DR: The terminal areas and cells of origin of the somatosensory projection to the mesencephalon in the monkey were investigated by the intraaxonal transport method.
Abstract: The terminal areas and cells of origin of the somatosensory projection to the mesencephalon in the monkey were investigated by the intraaxonal transport method. Following injection of wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) into the spinal enlargements, the lateral cervical nucleus (LCN), the dorsal column nuclei (DCN), or the spinal trigeminal nucleus, anterograde labeling was observed in several regions of the mid-brain. (1) Injection of tracer into the spinal enlargements resulted in dense terminal labeling in the parabrachial nucleus (PBN) and the periaqueductal gray matter (PAG); moderate termination was observed in the intercollicular nucleus (Inc), the intermediate and deep gray layers of the superior colliculus (SGI, SGP), the posterior pretectal nucleus (PTP), and the nucleus of Darkschewitsch (D); and scattered terminal fibers were seen in the cuneiform nucleus (CNF) and the pars compacta of the anterior pretectal nucleus (PTAc). The projections from the cervical enlargement to PAG, Inc, and the superior colliculus terminated more rostrally than those from the lumbar segments, indicating a somatotopic organization. (2) Terminal labeling after injection of tracer into LCN was found mainly in Inc, SGI, and SGP, but sparse labeling was also observed in the nucleus of the brachium of the inferior colliculus (BIN), PAG, PBN, PTP, and D. (3) The projection from DCN terminated densely in the external and pericentral nuclei of the inferior colliculus (ICX, ICP), Inc, SGI, SGP, PTP, PTAc, the nucleus ruber, and D, and weak terminal labeling was seen in BIN, PAG, and PBN. Comparisons of the anterograde labeling following injections involving both the gracile nucleus and the cuneate nucleus with that after injection restricted to the gracile nucleus alone suggested a somatotopic termination pattern in Inc, the superior colliculus, and the pretectal nuclei. (4) The patterns of projection from the laminar and alaminar parts of the spinal trigeminal nucleus differed: injection of tracer into the caudal part of the alaminar spinal trigeminal nucleus (nucleus interpolaris) resulted in dense anterograde labeling in SGI and SGP, moderate termination in Inc, and minor projections to PBN, PAG, and PTP, whereas after tracer injection into the laminar trigeminal nucleus (nucleus caudalis) terminal labeling was present only in PBN and PAG. Following injection of tracer into the midbrain terminal areas retrogradely labeled neurons were found in the spinal cord, LCN, DCN, and the spinal trigeminal nucleus, with the majority of labeled cells situated on the side contralateral to the injection site.(ABSTRACT TRUNCATED AT 400 WORDS)

214 citations

Journal ArticleDOI
TL;DR: Thalamic projections from trigeminal and certain other nuclei of the brainstem of the rat have been investigated using the technique of retrograde transport of horseradish peroxidase (HRP).
Abstract: Thalamic projections from trigeminal and certain other nuclei of the brainstem of the rat have been investigated using the technique of retrograde transport of horseradish peroxidase (HRP). The pattern of trigeminothalamic projections is very specifically related to the individual subnuclei of the complex. The Main Sensory Nucleus (MSN) provides profuse cross connections to the ventrobasal thalamus (VB); these arise exclusively from medium and small-sized neurons, but never from the large cells. In addition to these crossed connections, a small ipsilateral dorsal trigeminothalamic tract arises from the dorsal third of the most rostral part of the MSN; this is the only ipsilateral connection to VB found in the trigeminal complex. Subnucleus Oralis has no projections to the thalamus; it is suggested that it may be concerned primarily with reflex activation of the facial nucleus, with which it is co-extensive in the rostro-caudal axis. Subnucleus Interpolaris has a well-defined crossed projection of moderate size which arises from the large, medium and some of the small neurons. Subnucleus Caudalis has a sparse output to the thalamus and differs in its projections from rostral to caudal. At the most rostral level, all layers (marginal, transitional gelatinosa and magnocellularis) contain neurons which project to the thalamus; particularly conspicuous in this respect are the marginal neurons, most of which are strongly labelled. The presence of gelatinosa neurons projecting to the thalamus emphasizes a point made in earlier reports, that these neurons do not form an homogeneous population. At caudal levels, the marginal neurons are the major source of thalamic projections, while connections to the thalamus form deeper lying neurons are infrequent. With a single exception, the medullary reticular nuclei contained no neurons with thalamic connections; a small number of reticulo-thalamic neurons were found in the ventral pontine area. Marked labelling of the medial cuneate nucleus and moderate labelling of the gracilis and lateral cuneate nuclei occurred contralaterally to the injection site. A small numebr of medial cuneate and gracile neurons project to the ipsilateral thalamus. Projections from the solitary nucleus were always ipsialteral. The boundaries of individual subnuclei of the lateral sensory trigeminal complex in the rat have been redefined on the basis of cytological criteria; these are in good accord with the corresponding thalamic projection patterns.

210 citations


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