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.

Cerebellar and olivary projections of the external and rostral internal cuneate nuclei in the cat

Abstract: The cerebellar projection of the external cuneate nucleus and the adjoining rostral part of the internal cuneate nucleus were investigated by means of anterograde transport of tritiated leucine. The cuneocerebellar tract terminates as mossy fiber rosettes in the granular layer. The termination area has a more or less spherical form with its centre at the ipsilateral side. It comprises the anterior and posterior vermes bilaterally and the ipsilateral hemispheral parts of the anterior and simple lobules, the medial aspect of the ansiform lobule and the paramedian lobule. Within this area the mossy fiber terminals are arranged in continuous sagittal strips, some of them clearly separated from one another. The strips were found in the cerebellar modules A-D. Concomitant bilateral projections to several subdivisions of the inferior olive were found. Some of these provide the anatomical substrate for the simultaneous activation of a number of mossy and climbing fiber zones observed in the anterior lobe following stimulation of different forelimb nerves. No evidence was found for a termination of mossy fiber collaterals in the central cerebellar nuclei.

Extracellular K + activity and slow potential changes in spinal cord and medulla.

Abstract: In cats under Dial, repetitive stimulation of primary afferent fibers evokes a negative potential change in the cuneate nucleus or the dorsal horn of the lumbar spinal cord, which is associated with a clear increase in extracellular K+ activity, recorded by K+ selective microelectrodes.

Mesencephalic cuneiform nucleus and its ascending and descending projections serve stress-related cardiovascular responses in the rat.

Abstract: The aim of the present study was to explore the neuroanatomic network that underlies the cardiovascular responses of reticular formation origin in the region of the cuneiform nucleus (CNF). The study was performed in urethane anesthetized male Wistar rats. The left iliac artery was supplied with a catheter for the measurement of systemic blood pressure. Low intensity electrical stimulation of the mesencephalic reticular formation (MRF) in the vicinity of the CNF always resulted in pressor and bradycardiac responses, whereas stimulation in the parabrachial nucleus (PB) and Kolliker-Fuse nucleus (KF) led to a pressor response and a small tachycardiac response. The cuneiform area may be placed in the center of a circuit that serves a specific autonomic response pattern to stress: parallel activation of the sympathetic (pressor response) and parasympathetic limb (bradycardia). The efferent connections of the effective stimulation sites in the MRF and the CNF area, were investigated by anterograde tracing with the lectin Phaseolus vulgaris leucoagglutine (PHA-L). The CNF sends descending fibers to the gigantocellular reticular nuclei (GI), the motor nucleus of the vagus (DMNV) and nucleus tractus solitarius (NTS). These projections are probably involved in the bradycardiac response to stimulation. The descending pathway to the NTS/DMNV and GI may therefore be the parasympathetic limb of the circuit. Furthermore, the CNF sends ascending fibers to limbic forebrain areas and descending fibers to the PB-KF complex. The KF in its turn projects to the rostroventrolateral medullary nucleus (RVLM) and the intermediolateral cell column (IML). These latter projections are partly involved in producing the pressor response and thereby represent the sympathetic limb of the circuit. Accordingly, the transection of the descending fibers from the CNF to the PB-KF complex resulted in a decreased pressor and an increased bradycardiac response. This suggests that a baroreceptor reflex-induced bradycardia which results from blood pressure increase can be excluded as the origin of the stimulation-induced bradycardia, and that the pressor and bradycardiac responses are two independent moieties. It cannot be excluded that ascending fibers from the CNF are also involved in producing the pressor response. On the basis of the present physiological and neuroanatomical study, a brain circuit has been proposed in which the cuneiform nucleus has a central position. The described brain circuit may serve a passive coping strategy to novel, painful or threatening stimuli during which the animals show orientation/attention or freezing behavior accompanied by a bradycardiac and pressor response.