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A Rustioni

Publications and source records attributed to A Rustioni.

At least 91 records · Page 5Linked to original sources
PubMed1979

Dorsal column nuclei and ascending spinal afferents in macaques.

Cell populations and thalamic projections of the dorsal column nuclei in macaques have been investigated in the medullae of normal animals and of animals with injections of horseradish peroxidase in the nucleus ventralis posterolateralis. In the same species, the course, distribution and origin of ascending non-primary pathways to the dorsal column nuclei have been demonstrated with the aid of degeneration methods, 3H-amino acid autoradiography and retrograde axonal transport of horseradish peroxidase. Non-primary afferents to the gracile and cuneate nuclei ascend mainly in the dorsal columns and, to a lesser extent, in the dorsal part of the lateral funiculus. Afferents originating from lumbar segments and ascending in the lateral funiculus terminate mainly in the rostral part of the gracile nucleus while those ascending in the dorsal columns distribute throughout most of the rostrocaudal extent of the same nucleus. Afferents from brachial levels terminate mainly in the cuneate nucleus and in the external cuneate nucleus. Degeneration and autoradiographic material concurrently demonstrate that non-primary afferents to the cuneate nucleus terminate preferentially within certain cytoarchitectonic subdivisions of this nucleus. Ascending spinal afferents to the dorsal column nuclei originate mainly from the ipsilateral dorsal horn, particularly from its medial part at upper cervical levels and from a band of gray, throughout the cord, largely corresponding to lamina IV and adjacent laminae. Large neurons along the lateral border of the ventral horn at lumbar levels may also contribute non-primary afferents to the ipsilateral dorsal column nuclei. These anatomical results provide some cues to a revised view of the organization of the dorsal column nuclei in monkeys and, taken together with recent electrophysiological and clinical data, contribute to a re-evaluation of some functional aspects of the dorsal column-medial lemniscal system of primates.

Afferent Pathways↗
PubMed1978

Thalamic projections to S-I in macaque monkey.

The organization of thalamic input to functionally characterized zones in primary somatosensory cerebral cortex (S-I) of macaque monkeys (Macaca mulatta) was investigated using the method of labelling by retrograde transport of horseradish peroxidase (HRP). It was found that the cell columns positioned at the posterior margin of the band of cortex representing a given body region receive thalamic input from a posterior level of the ventroposterior thalamic nucleus (VP), and that cell columns at successively more anterior positions within that band receive input from successively more anterior levels of VP. The extreme posterior and anterior margins of the S-I hand, foot and face areas receive input from neuron populations which are not as widely separated in the anteroposterior dimension of VP as the neurons projecting to the extreme anterior and posterior margins of the proximal limb and trunk representations in S-I. These characteristics of the organization of the projections from VP to S-I are consistent with the view that the body representations in VP and S-I have the same connectivity and differential submodality distribution; and with the idea that thalamocortical conncetions only exist between functionally equivalent neuron populations in VP and S-I.

Adaptation, Physiological↗
PubMed1977

Cortical cells projecting to the dorsal column nuclei of rhesus monkeys.

Corticals cells projecting to the dorsal column nuclei (DCN) of Rhesus monkeys have been identified after unilateral or bilateral injection of horseradish peroxidase (HRP) into the dorsal medulla. HRP-positive neurons identifiable as the source of cortico-DCN projections were pyramidal cells in layer V whose largest diameters ranged from 12--31 micron. Cortico-DCN neurons were concentrated in the trunk, fore- and hindlimb regions of area 4 and of SI, and to a lesser extent in SII. This distribution is comparable to the topographical distribution of cortico-DCN neurons in cats. However, cortico-DCN neurons in monkeys are also numerous in at least part of the supplementary motor cortex and in area 5. The results suggest that cortical neurons in several different cytoarchitectonic areas may exert direct control upon cells in the DCN and that the functional role of cortic-DCN projections ought not be view as a simple "feedback" system.

Animals↗
PubMed1977

Spinal neurons project to the dorsal column nuclei of rhesus monkeys.

Cells of origin of ascending nonprimary afferents to the dorsal column nuclei of rhesus monkeys have been identified in the spinal cord by the retrograde transport of horseradish peroxidase. These neurons are mainly located in lamina IV and medially in more ventral laminae of the dorsal horn on the side ipsilateral to the medullary injection. Large neurons in the ventral horn ("spinal border cells") also appear to project to the ipsilateral dorsal medulla. The dorsal column nuclei of a primate thus are the recipient not only of ascending dorsal root fibers but also of a more complexly integrated spinal input.

Afferent Pathways↗
PubMed1977

Identification of cells or origin of non-primary afferents to the dorsal column nuclei of the cat.

In order to identify cells of origin in the spinal cord of non-primary afferents to the dorsal column nuclei (DCN), the retrograde transport of horseradish peroxidase (HRP) has been utilized in adult cats. 10 to 30% HRP was injected bilaterally (0.6 mul per side) in the dorsal medulla of nine cats. In most instances the spread of the injected enzyme extended a few millimeters rostrocaudally and infiltrated the DCN as well as other nuclei and fiber tracts. Labelled cells in these cases are numerous in the upper cervical, brachial and lumbosacral cord but are sparse in thoracic segments below T1. At upper cervical levels (C1-C4) HRP-positive neurons are distributed throughout the grey matter but are especially concentrated in the medial part of lamina VI. Cells projecting to the dorsal medulla are mainly localized in lamina IV and, more ventrally, along the medial border of the dorsal horn in the brachial and lumbosacral cord. Labelled cells at these levels are also scattered within lamina I and laminae VI through VII in cases in which the focus of the injection involved extensive portions of the medulla. From cases in which bilateral HRP injections were preceded by spinal tractotomy, it appears that the axons of at least the majority of labelled cells in lamina IV ascend in the ipsilateral dorsal quadrant of the spinal cord. In another group of adult cats, 0.1 to 0.25 mul of 30 to 50% HRP was injected unilaterally in the dorsal medulla at the level of, or rostral to, the obex. With these volumes of exogenous enzyme, an intense reaction product is largely confined within the limits of the DCN. Labelled cells in these cases are found almost exclusively in the medial part of lamina VI at upper cervical levels and, at brachial and lumbosacral levels, throughout lamina IV and medially in lamina V on the side of the cord ipsilateral to the injection. The results are discussed in relation to the organization of the dorsal horn ascending pathways with special reference to cells or origin of the spinocervical tract.

Afferent Pathways↗
PubMed1976

Cortical cells projecting to the dorsal column nuclei of cats. An anatomical study with the horseradish peroxidase technique.

The retrograde transport of horseradish peroxidase (HRP) has been used to label cortical neurons which give origin to descending projections to the dorsal column nuclei (DCN) in kittens and adult cats. HRP was injected unilaterally or bilaterally into the dorsal medulla at, or rostral to, the level of the obex, and, in most cases, retrogradely transported HRP was visualized in cortical neurons by incubation of serial 40 mum coronal or sagittal frozen sections. In the remaining cases, 1 mm coronal or sagittal slabs through the anterior part of the cerebral hemisphere were cut and incubated en bloc, and embedded in celloidin for sectioning (40 mum). HRP-positive neurons identifiable as the source of cortical projections to the DCN were layer V pyramidal cells whose largest diameter ranged from 20 to 45 mum: no "giant" cells were labelled. The cells appeared concentration in the fore-and hindlimb regions of the sensorimotor cortex and, to a lesser extent, in the second somatosensory area contralateral to the injected side. Labelled neurons were especially numerous in the upper bank of the cruciate sulcus and in the medial wall of the posterior sigmoid gyrus which respectively form parts of areas 4 and 3a (Hassler and Muhs-Clement, '64). The number of labelled neurons progressively diminished in the first somatosensory area proper (areas 3b, 1 and 2). Ipsilaterally, fewer labelled neurons were present, mainly in areas 4 and 3a. These results are in genral agreement with previous anatomcial and electrophysiological studies. It is suggested that previous results based upon lesions or electrical stimulation of the cerebral cortex in cats have failed to reveal adequately the cortical regions containing the bulk of the cells projectng to the DCN, since these regions have escaped selective experimental manipulation due to their relative inaccessibility.

Animals↗
PubMed1975

Dorsal column nuclei projections to the cerebellar cortex in cats as revealed by the use of the retrograde transport of horseradish peroxidase.

The existence of a cerebellar projection from the dorsal column nuclei (gracile and cuneate nuclei, DCN) has been proposed on electrophysiological grounds but questioned when studied with neuroanatomical techniques. The retrograde transport of horseradish peroxidase (HRP) has been used for the present study and provides anatomical evidence of a DCN-cerebellar pathway. In adult cats, 1 to 6 mul of 30% HRP were injected in pars intermedia of the anterior lobe (lobules IV-V), in paramedial lobule and in vermis of the anterior (lobules IV-V) and of the posterior lobe (lobule VII). After survival of 24 to 48 hours, all animals were perfused with a double aldehyde mixture and serial 40 mu sections through the medulla oblongata were incubated for visualization of HRP. In all cases, medullary nuclei known to project to the injected cortical regions of the cerebellum contained HRP-positive neurons mainly ipsilateral to the injection (e.g., external cuneate nucleus) or mainly contralateral to it (e.g., inferior olivary complex). Following ipsilateral injections in either the paramedian lobule or the pars intermedia, HRP-positive neurons in the cuneate nucleus were concentrated in its rostral portion where multipolar cells with radiating dendrites predominate. In contrast, none of the clusters region, in the caudal part of the cuneate nucleus, displayed HRP-positive granules. In cases in which the anterior vermis was injected a few labelled cells were present in the rostral part of the gracile nucleus but not in the clusters region of this nucleus. No labelling of DCN neurons was evident after posterior vermis injection. To compare the distribution of cells contributing to the DCN-cerebellar pathway with that of thalamic relay cells in the DCN, 0.5 to 3 mul of 30% HRP were injected in the nucleus ventralis posterolateralis of the thalamus in another series of cats. Contralateral to the thalamic injection, labelled cells were concentrated in the clusters region of the gracile and cuneate but rostrally in these nuclei they were scattered among unlabelled neurons. The preferential location in the DCN of cells which project to the cerebellum and of cells which project to the thalamus stresses the heterogeneous organization of these nuclei along the rostrocaudal axis. Further, the results indicate that regions of the DCN which have been distinguished on the basis of cytoarchitectonics (Kuypers and Tuerk, '64) and of afferents (Rustioni, '73, '74) differ also in their efferent projections.

Animals↗
PubMed1975

Dorsal column nuclei afferents in the lateral funiculus of the cat: distribution pattern and absence of sprouting after chronic deafferentation.

In adult cats the successive degeneration technique has been used to demonstrate the existence and distribution pattern of lateral funicular fibers to the dorsal column nuclei (DCN) originating from the brachial and thoracic cord. In a first operation, interruption of the dorsal columns at appropriate cervical levels and of the lateral funiculus at low thoractic levels was performed. Thirteen months later, a lesion was made in the lateral funiculus at upper brachial or uppermost thoracic levels. Fiber degeneration in the DCN consequent to this second operation is not contaminated by damage to dorsal roots or by interruption of lateral funicular afferents from lumbo-sacro-coccygeal segments. All animals were sacrificed 7 days after the second operation. Serial sections through the medulla oblongata, impregnated with the Fink-Heimer technique, show that fibers ascending from brachial levels in the dorsal part of the lateral funiculus reach the cuneate nucleus either by a dorsomedial route through the tegmentum or by cuneate nucleus either by a dorsomedial route through the tegmentum or by ascending in the restiform body. Degenerated fibers distribute selectively to the rostral part, and to a lesser extent to the base of the cuneate nucleus. Only very few fibers ascending from thoracic levels in the lateral funiculus distribute to the DCN. In another group of animals, not previously deafferented, a lesion of the lateral funiculus was made at upper brachial levels. This group served as a control to assess whether sprouting had occurred in the chronic preparations as a consequence of the long-term deafferentation. Comparison of the results in the cuneate nucleus of the two groups of animals shows no difference in the pattern of distribution or in the amount of degenerated fibers in this nucleus. These observations are discussed in relation to the question of collateral sprouting in the adult mammalian central nervous system.

Animals↗