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.

Three ascending tracts activated from group i afferents in forelimb nerves of the cat.

Abstract: Publisher Summary Group I muscle afferents in hindlimb nerves activate two ascending tracts—the dorsal and the ventral spino-cerebellar tract (DSCT and VSCT). Group I afferents in forelimb nerves activate three ascending pathways. The rostra1 spino-cerebellar tract (RSCT) originates from cell bodies at, or slightly above, the level of the dorsal root entrance, ascends ipsilaterally in the middle third of the lateral funiculus, and terminates in a characteristic manner in the anterior cerebellar lobe. It receives monosynaptic excitation from high threshold group I muscle afferents, identical with tendon organ afferents. The cuneo-cerebellar tract contains one component that is monosynaptically activated from very low threshold group I muscle afferents, identical with muscle spindle afferents. The third pathway is a projection to the cerebral cortex of large muscle spindle afferents. The group I afferents ascend in the dorsal funiculus and activate monosynaptically cells in the main cuneate nucleus, which give origin to a component of the medial lemniscus.

Encoding of limb state by single neurons in the cuneate nucleus of awake monkeys

Abstract: The cuneate nucleus (CN) is among the first sites along the neuraxis where proprioceptive signals can be integrated, transformed, and modulated. The objective of the study was to characterize the proprioceptive representations in CN. To this end, we recorded from single CN neurons in three monkeys during active reaching and passive limb perturbation. We found that many neurons exhibited responses that were tuned approximately sinusoidally to limb movement direction, as has been found for other sensorimotor neurons. The distribution of their preferred directions (PDs) was highly non-uniform and resembled that of muscle spindles within individual muscles, suggesting that CN neurons typically receive inputs from only a single muscle. We also found that the responses of proprioceptive CN neurons tended to be modestly amplified during active reaching movements compared to passive limb perturbations, in contrast to cutaneous CN neurons whose responses were not systematically different in the active and passive conditions. Somatosensory signals thus seem to be subject to a “spotlighting” of relevant sensory information rather than uniform suppression as has been suggested previously.

Light and Electron Microscopical Studies of the Substance P Innervation of the Dorsal Column Nuclei and the Lateral Cervical Nucleus in the Primate

Abstract: In 2 monkeys of the species Macaca fascicularis the three dorsal column nuclei and the lateral cervical nucleus have been investigated immunocytochemically with antiserum against Substance P.The Substance P labeling was widely spread but rather sparse. It occurred in small structures of the size of boutons in the gracile, main cuneate and lateral cervical nucleus. The most intensive labeling of the gracile nucleus was found in the dorsal border of the nucleus and the lateral part of the caudal division. At the border between the spinal trigeminal nucleus and the triangular part of the cuneate nucleus Substance P labeling was also increased but mainly localized to the former nucleus. In the pars rotunda and the caudal part of the main cuneate nucleus there was a more intense labeling laterally especially at the obex level. In the lateral cervical nucleus Substance P positive structures seemed evenly spread and somewhat more numerous than in the gracile and main cuneate nucleus. Electron microscopy demonstr...