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.

Dorsal column nuclei in a prosimian primate (Galago senegalensis). II. Cuneate and lateral cuneate nuclei: morphology and primary afferent fibers from cervical and upper thoracic spinal segments.

Abstract: The morphology and brachial cord primary afferent projections of the cuneate and lateral cuneate nuclei have been studied in the lesser bushbaby. The cuneate nucleus was divided into three regions. From caudal to rostral these were the large cell, cell column and rostral regions. Primary afferents from C2, C4, C6, C7, C8, T1 and T3 terminated within distinct partially overlapping terminal zones in the ipsilateral large cell and cell column regions of the cuneate nucleus (CN) and the lateral cuneate nucleus (LCN). Segmentotopic was the greatest in the rostal region of the CN due to a more diffuse projection pattern. In the LCN, the transverse terminal fields appeared as curved mediolaterally oriented laminae. In each case, ascending fibers of passage from C4, C6, and C7 in the cuneate fasciculus were organized so that two distinct fiber laminae were present. The separation of fibers and the formation of the two ascending laminae were completed either within two segments rostral to their respective level of entry (for C6 and C7 lesions) or in the caudal medulla (for C4 lesion). For each of these segments, the laminae consisted of a small dorsomedial one and a large lateral one. The organization of primary afferents from one segment into two ascending fiber laminae in the cuneate fasciculus was reflected in a differential termination pattern within both the CN and LCN. The results of this study were discussed relative to earlier anatomical and physiological studies on the DCN in other animals.

The effect of etomidate on sensory transmission in the dorsal column pathway in the urethane-anaesthetized rat.

Abstract: The effect of Etomidate, a general anaesthetic, on sensory afferent transmission was measured in the dorsal column pathway in urethane-anaesthetized rats. Extracellular recordings were made of peripherally evoked responses by single cells in the cuneate nucleus, ventroposterolateral nucleus of the thalamus and laminae IV–VI of the primary somatosensory cortex. Cortical mass responses were also recorded. In further experiments, cortical mass responses were evoked antidromically by stimulation in the pyramidal tract. The effect of incremental administration of Etomidate on evoked responses was recorded. These results are compared with the previously reported effects of urethane, a ‘conventional’ anaesthetic. Etomidate did not alter cuneate or ventroposterolateral thalamic cell responses but it caused a dose-dependent reduction in cortical cell responsiveness. It failed to alter antidromically evoked cortical mass responses. Etomidate differs from the majority of anaesthetics, which act in the thalamus, and appears to cause perturbation at the cortical level.

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 nonuniform 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.NEW & NOTEWORTHY The cuneate nucleus (CN) is the somatosensory gateway into the brain, and only recently has it been possible to record these signals from an awake animal. We recorded single CN neurons in monkeys. Proprioceptive CN neurons appear to receive input from very few muscles, and their sensitivity to movement changes reliably during reaching relative to passive arm perturbations. Sensitivity is generally increased, but not exclusively so, as though CN "spotlights" critical proprioceptive information during reaching.

Presynaptic and postsynaptic inhibition on transmission of cutaneous afferent volleys through the cuneate nucleus during sleep.

Abstract: Durante i movimenti rapidi oculari caratteristici della fase desincronizzata di sonno si osserva una depressione fasica della risposta lemniscale alla stimolazione di fibre cutanee. Questa modulazione ipnica della risposta lemniscale e dovuta a meccanismi di inibizione presinaptica e postsinaptica.