Showing papers on "Cuneate nucleus published in 1983"

Central distribution of efferent and afferent components of the cervical branches of the vagus nerve. A HRP study in the cat.

Abstract: Central distribution of efferent and afferent components of the cervical branches of the vagus nerve in the cat was studied by applying horseradish peroxidase (HRP) to the superior laryngeal nerve (SLN), pharyngeal branch (PhB), recurrent laryngeal nerve (RLN) or middle portion of the cervical trunk of the vagus nerve (CTV). After applying HRP to the SLN, PhB or RLN, labeled neurons were mainly seen ipsilaterally in the ambiguus nuclear complex (Amb) at levels of the rostral, middle, or caudal portions of the Amb, respectively. After application of HRP to the CTV, labeled neurons were distributed ipsilaterally throughout the Amb. Neurons in the lateral reticular formation medial to the spinal trigeminal nucleus were also labeled ipsilaterally with HRP from the SLN or CTV; these neurons appeared to be the caudal extension of the inferior salivatory nucleus. Neurons within the dorsal motor nucleus of the vagus nerve (DMV) were labeled ipsilaterally only after HRP application to the CTV. The axons of neurons in the rostral Amb and the lateral reticular formation, labeled retrogradely from the SLN or CTV, ran dorsomedially to form a genu in the dorsomedial tegmental region near the floor of the fourth ventricle, and then turned and left ventrolaterally from the medulla oblongata. On the other hand, axons of neurons in the caudal two-thirds of the Amb, labeled retrogradely from the PhB, RLN or CTV, ran dorsomedially to a region ventral to the DMV, where they turned ventrolaterally to form loops before leaving the brainstem. A few axons of neurons in the rostralmost regions of the DMV were also found to form a genu near the floor of the fourth ventricle before running ventrolaterally to leave the brianstem. Axon terminals in the solitary nucleus (Sn) were transganglionically labeled most densely in the medial and interstitial subnuclei from the SLN, in the medial and dorsolateral subnuclei from the RLN, and in the medial and gelatinous subnuclei from the CTV. Application of HRP to the SLN also revealed labeling of axon terminals in the principal sensory and spinal trigeminal nuclei, the medial cuneate nucleus and the dorsal horn of the C1 and C2 cord segments.

The Corticocuneate Pathway in the Cat: Relations among Terminal Distribution Patterns, Cytoarchitecture, and Single Neuron Functional Properties

Abstract: A combined anatomical and physiological strategy was used to investigate the organization of the corticocuneate pathway in the cat. The distribution of the corticocuneate projection was mapped by means of the anterograde horseradish peroxidase (HRP) labeling technique and correlated with the nuclear cytoarchitecture in Nissl and Golgi material, the distribution of retrogradely labeled relay cells after HRP injections in the ventrobasal complex of the thalamus, and the topographic organization derived from single-and multiunit recordings in the decerebrate, unanesthetized cat. This approach provided details about the arrangement of the corticocuneate pathway that were not available from previous studies with anterograde degeneration methods.On the basis of cytoarchitectonic and connectional features, a number of subdivisions are identified in the cuneate nucleus, each of which is associated with characteristic functional properties. In agreement with previous studies, it is found that a large portion of th...

Depolarizing responses to glycine, beta-alanine and muscimol in isolated optic nerve and cuneate nucleus.

Abstract: Concentration-dependent depolarizations were evoked by glycine and beta-alanine 5 X 10(-4)-10(-2)M and by the gamma-aminobutyric acid (GABA) analogue, muscimol 10(-6)-10(-4)M The maximal response to glycine was several-fold higher than that to muscimol on optic nerve but the reverse was found on the dorsal funiculus fibres in the cuneate nucleus beta-Alanine evoked a similar maximal response to glycine on optic nerve but a considerably higher maximum than glycine in the cuneate nucleus Strychnine was 195 times more potent as a glycine antagonist (pA2 = 658) than as a muscimol antagonist Bicuculline was 156 times more potent as a muscimol antagonist than as a glycine antagonist Other antagonists of muscimol, ie tubocurarine, picrotoxin and leptazol, and potentiators of muscimol, ie pentobarbitone and flurazepam, had little or no effect on responses to glycine Responses to beta-alanine had pharmacological properties compatible with a mixed action on both GABA and glycine receptors The rat isolated optic nerve appears to be a useful preparation for studying the pharmacology of the neuronal glycine receptor plus chloride ionophore complex

Projections of nucleus caudalis and spinal cord to brainstem and diencephalon in the hedgehog (Erinaceus europaeus and Paraechinus aethiopicus): a degeneration study.

Abstract: In the light of hypotheses related to the evolution of pain-carrying systems in mammals, terminal projection fields in brainstem and diencephalon of efferents of nucleus caudalis (NC) of the spinal trigeminal complex and spinal cord were determined in hedgehog by using Nauta-Gygax and Fink-Heimer silver techniques for degeneration. Unilateral NC lesions resulted in medullary degeneration in the ventral portion of NC contralaterally and bilaterally in cuneate nucleus (CU) and reticular formation. Pontine degeneration was noted ipsilaterally in medial (PBM) and lateral (PBL) parabrachial, facial motor (VII), and interpolar, oral, and main sensory trigeminal nuclei; degeneration in reticular formation was bilateral. Midbrain degeneration was seen bilaterally in caudal superior colliculus (SC), inferior colliculus (IC), periaqueductal gray, and tegmentum. In thalamus, projections to ventroposterior nucleus (VP) were contralateral and concentrated in a crescent extending along the lateral one-third-to-one-half and ventral border of the nucleus. Bilateral degeneration fields were noted in a dorsomedial sector of the "ventral nuclear field," posterior complex (PO), and mediodorsal nucleus (MD), the degeneration always heavier contralaterally in these nuclei. Sparse degeneration was noted in the medial most portions of the medial geniculate nuclei bordering PO and VP. In rostral diencephalon, bilateral degeneration was traced from the inferior thalamic peduncle to the lateral hypothalamic area (LH). Unilateral spinal cord lesions made between C7 and T1 vertebrae resulted in medullary degeneration in NC contralaterally, ipsilaterally in CU and lateral cuneate nucleus, and bilaterally in gracile nucleus, inferior olivary complex, and reticular formation. Pontine degeneration was limited to ipsilateral PBL and bilaterally to VII. Midbrain degeneration was found bilaterally in IC, SC, nucleus sagulum, and tegmentum; a minor projection was noted in interpeduncular nucleus. In thalamus, projections were confined to ipsilateral PO and zona incerta. In rostral diencephalon bilateral fields were noted in LH. NC terminations in PO and VP parallel results of research in hedgehogs on thalamic projections of the dorsal column nuclei (Jane and Schroeder, '71), and particularly the location in VP of most cells responsive to stimulation of the face (Erickson et al., '67). This suggests that somatic input from NC, some of which may be pain-specific, reaches thalamic areas, a portion of whose neurons are characterized as polymodal and at least partially convergent for somatotopy. These results are consistent with the thesis that specific sensory thalamic nuclei evolved from a diffuse sensory region. Response properties of neurons in the dorsomedial portion of the ventral nuclear field, an area which are also received NC efferents, are not known. Last, NC projections to MD and LH implicate the role of "limbic" aspects of nociception.

Afferent projections of the rat major occipital nerve studied by transganglionic tansport of HRP

Abstract: The central projection fields of cutaneous neurons of the rat's major occipital nerve have been investigated using the method of transganglionic transport of horseradish peroxidase (HRP), with tetramethyl-benzidine according to Mesulam (1978) as the chromogen. Furthermore, the course of the nerve, diameter distribution of myelinated axons, and diameter distribution of HRP-labeled perikarya of spinal ganglion cells belonging to this nerve have been studied. Following HRP application to the proximal stump of the cut nerve, labeled structures were found ipsilaterally in the cervical spinal cord and in the medulla oblongata. In the spinal cord, reaction product was mainly concentrated in the lateral parts of laminae I–III of the dorsal horn in segments C2 and C3. In C1, primary afferent terminals were more sparsely distributed and restricted to laminae I and II. Reaction product was also seen in the tract of Lissauer in segments C1–C4. In the medulla oblongata HRP labeled structures were observed in the medial cuneate nucleus, in the rostral part of the external cuneate nucleus, and in the nucleus of the spinal tract of the trigeminal nerve. A possible somatotopic arrangement of central terminals of cutaneous neurons within the cervical dorsal horn, as well as differences between the projection fields of muscle and skin afferents within the upper cervical cord and caudal medulla are discussed.

The Projection of Cervical Primary Fibers to the DCN of the Squirrel, Sciurus niger: Fiber Sorting in the Dorsal Columns

Abstract: The course and terminal distribution of cervical primary afferents in the dorsal column nuclei were studied in the fox squirrel, Sciurus niger. Unilateral rhizotomies were performed at cervical levels C3, C4, C5, C6 and C8. For all spinal levels studied except C8, degeneration in the medullary cuneate fasciculus was present within two distinct groups. They included a large oblique lateral lamina and a small superficial group of degeneration. The superficial group was horizontal, located medial to the large lamina and appeared to be formed by the medial shifting of fibers away from the initial larger group. Fibers in the large primary lamina appeared to terminate primarily in the ventrolateral areas of the cuneate nucleus. Fibers from the superficial group, however, appeared to project mostly to dorsal cuneate nuclear areas. Hence, the dual transverse terminal patterns for cervical fibers in the cuneate nucleus appeared to be related directly to a fiber sorting process that involved the formation of two often separate ascending fiber groups in the cuneate fasciculus. The results of this study are compared with the mechanosensory mapping of the dorsal column nuclei in the squirrel.

Contralateral as Well as Ipsilateral Projections to Raccoon Cerebellum from External Cuneate Nuclei and Cell Groups f and x

Abstract: To assess the locations and densities of cells in the dorsal medulla giving rise to ipsilateral versus contralateral projections to the mechanosensory regions of cerebellar cortex in the anterior lobe