摘要:

AbstractIt has been previously assumed that the asymmetry of the monocular optokinetic nystagmus (OKN) of lateral‐eyed mammals is caused by an absence of visual cortex projections to directional selective neurons in the pretectal nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT‐DTN). In contrast to this generally accepted hypothesis, we present multiple evidence that OKN‐related neurons in the rat NOT‐DTN in fact do receive input from the visual cortex.We studied the corticofugal projection to NOT‐DTN physiologically, with extracellular single unit recording and electrical stimulation of the optic chiasma and the visual cortex, and anatomically, using retrograde and anterograde tracing techniques. In particular we focussed our attention on the NOT‐DTN neurons, which control eye movements during OKN. All OKN‐related NOT‐DTN cells were activated after optic chiasma stimulation. Forty‐five percent of these neurons were also activated after stimulation of the visual cortex (VC). The majority of neurons activated from VC (80%) also responded to monocular stimulation of either eye. On the contrary, most of the neurons that responded to stimulation of the contralateral eye only were not activated from VC. After injection of fluorescent latex microspheres into the NOT‐DTN, retrogradely labeled neurons were found in areas 17, 18, and 18A of the visual cortex.Phaseolus vulgarisleucoagglutinin injected into the visual cortex anterogradely labeled fibres and terminals throughout the NOT‐DTN complex. Labeled boutons were found in close proximity to OKN‐related NOT‐DTN cells, selectively stained after horseradish peroxidase (HRP) injections into the inferior olive. Our results demonstrate that NOT‐DTN cells in the rat, which are involved in the generation of horizontal OKN, receive a direct input from th

ISSN:0092-7317    

DOI:10.1002/cne.903300202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn order to investigate the topography and subdivisions of the human dorsal motor nucleus of the vagus nerve (10), studies were conducted using cyto‐ and chemoarchitectonic (acetylcholinesterase and substance P‐like immunoreactivity) and computer reconstruction techniques.The six brainstems examined were obtained within 17 hours postmortem from adults with no known neurological disorders. Serial sections cut in transverse, sagittal, and coronal planes were stained with cresyl violet, or tested for acetylcholinesterase or substance P. The neurons of the 10 (16,826 ± 967) displayed cyto‐ and chemoarchitectonic heterogeneity and could be classified into six types. Types I–V consist of presumed vagal motor neurons (13,802 ± 844), while the remaining type (Type VI) consisted of presumed interneurons (3,024 ± 769). The 10 was subdivided into nine subnuclei grouped regionally into rostral, intermediate, and caudal divisions on the basis of neuronal morphology, cell density, and differential AChE and substance P reactivities. The rostral division contains the dorsorostral (DoR) and the ventrorostral (VeR) subnuclei; the intermediate division contains the rostrointermediate (RoI), dorsointermediate (DoI), centrointermediate (CeI), ventrointermediate (VeI), and caudointermediate (CaI) subnuclei; the caudal division (Ca) is not subdivided. Morphologically, small round or oval cells populate the VeR and VeI. Medium‐sized oval cells occur in the DoR, CeI, and Ca, while medium‐sized fusiform and multipolar cells are the main features of CaI. Large triangular cells appear mainly in DoI. Glial cells show the highest predilection for CeI, lowest densities in DoI and medial fringe subnucleus (MeF), and intermediate densities in the remaining six subnuclei. VeI showed the strongest AChE reactivity. Although the cell bodies of VeR and DoI are AChE positive, the neuropil (background) is weakly stained. Densely distributed fine granular substance P‐like immunoreactivity occurs throughout the entire nucleus, while the intermediate and caudal divisions contain substance P‐like‐immunoreactive neurons. Three‐dimensional computer reconstructions afforded an appreciation of the distinctiveness of the intermediate division (a division that contains the majority of cells) and the caudal division, which displays the lowest density of presumed vagal motoneurons. It is possible that the subnuclei identified herein form functional units inner

ISSN:0092-7317    

DOI:10.1002/cne.903300203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe distribution of nigrothalamic and cerebellothalamic projections was investigated in the dog by a double labeling strategy combining the anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) and tritiated amino acids. Following tritiated amino acid injections into the substantia nigra pars reticulata (SNr) and WGA‐HRP injections into the contralateral cerebellar nuclei, we found that the nigrothalamic and cerebellothalamic afferents distribute to three main targets: the central portion of the ventral anterior nucleus (VA) and the ventral lateral nucleus (VL), the internal medullary lamina (IML) region, which includes the paralaminar VA, the mediodorsal nucleus (MD) and the central lateral nucleus (CL), and finally the ventromedial nucleus (VM). We observed three distribution patterns of labeled fibers: (a) Dense single label was observed in the central portion of VA following the SNr injections and in VL following the cerebellar nuclei injections. (b) A complementary pattern consisting of alternating foci of nigral and cerebellar label was found in the IML region. This pattern was also observed in the caudal intralaminar nuclei where cerebellar label predominated in the centrum medianum (CM), while the parafascicular nucleus (Pf) primarily contained nigral label. (c) An overlapping pattern of autoradiographic and WGA‐HRP label was found in the lateral half of the VM. Overall, the distribution of nigrothalamic and cerebellothalamic projections was widespread throughout much of rostrocaudal thalamus. However, the pattern of projections varied along a continuum from lateral to medial thalamus. In lateral thalamus, nigral and cerebellar projections distributed to separate nuclei while in medial thalamus, the projection pattern changed to focal and complementary in the IML and overlapping in VM. Taken together, these thalamic projections may constitute crucial links in different functional channels involved in alerting and orienting mechanisms associated with motor behavior. Our findings also suggest that the organization of motor thalamic afferents in the dog shares similarities with the segregated and parallel circuitry characteristic of primates as well as with the overlapping and converging circuits of rodents and other carni

ISSN:0092-7317    

DOI:10.1002/cne.903300204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe preoptic area contains most of the luteinizing hormone releasing hormone immunoreactive neurons and numerous monoaminergic afferents whose cell origins are unknown in sheep. Using tract tracing methods with a specific retrograde fluorescent tracer, fluorogold, we examined the cells of origin of afferents to the medial preoptic area in sheep. Among the retrogradely labeled neurons, immunohistochemistry for tyrosine hydroxylase, dopamine‐β‐hydroxylase, phenylethanolamine N‐methyltransferase, and serotonin was used to characterize catecholamine and serotonin fluorogold labeled neurons.Most of the afferents came from the ipsilateral side to the injection site. It was observed that the medial preoptic area received major inputs from the diagonal band of Broca, the lateral septum, the thalamic paraventricular nucleus, the lateral hypothalamus, the area dorsolateral to the third ventricle, the perimamillary area, the amygdala, and the ventral part of the hippocampus. Other numerous, scattered, retrogradely labeled neurons were observed in the ventral part of the preoptic area, the vascular organ of the lamina terminalis, the ventromedial part of the hypothalamus, the periventricular area, the area lateral to the interpeduncular nucleus, and the dorsal vagal complex. Noradrenergic afferents came from the complex of the locus coeruleus (A6/A7 groups) and from the ventro‐lateral medulla (group A1). However, dopaminergic and adrenergic neuronal groups retrogradely labeled with fluorogold were not observed. Serotoninergic fluorogold labeled neurons belonged to the medial raphe nucleus (B8, B5) and to the serotoninergic group situated lateral to the interpeduncular nucleus (S4).In the light of these anatomical data we hypothesize that these afferents have a role in the regulation of several functions of the preoptic area, particularly those related to reproduction. Accordingly these afferents could be involved in the control of luteinizing hormone releasing hormone (LHRH) pulsatility or of preovulatory LH

ISSN:0092-7317    

DOI:10.1002/cne.903300205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe present study is the first comprehensive mapping of glial fibrillary acidic protein (GFAP)‐immunopositive structures in the avian brain. Two main types of GFAP‐immunopositive elements were observed: (1) nonbranching fibers, occasionally twisted or varicose, and (2) star‐shaped cells. Long immunostained fibers orignate from the lateral ventricle to form three bundles. Fibers of the dorsal group, emanating from the dorsal/lateral corner of the ventricle, course in lateral, anterior, and ventral directions forming a semidome, which separates the outer pallial (lateral cortical) regions from the underlying striatal mass. The middle group of fibers is directed anteriorly and laterally corresponding to the laminae frontales superior and suprema. The ventral fiber bundle is conical and traverses the lobus parolfactorius, crossing also the lamina medullaris dorsalis (the latter consisting mainly of star‐shaped cells). The hippocampus, septum, and hypothalamus also contain straight radial fibers. In some areas, given their variable orientation, the fibers cannot be regarded as merely persisting radial glia. In the telencephalon, the nuclei basalis, accumbens, ectostriatum, paleostriatum primitivum, and the ventral paleostriatum are particularly rich in GFAP‐positive cells, whereas the neostriatum, hyperstriatum, and paleostriatum augmentatum are almost devoid of GFAP labelling. Certain nuclei of the thalamus and the lower brainstem are conspicuous by their low levels of GFAP immunoreactivity. The Bergmann glia were GFAP‐imm

ISSN:0092-7317    

DOI:10.1002/cne.903300206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe ipsilateral cortical connections of primary motor cortex (M1) of owl monkeys were revealed by injecting WGA‐HRP and fluorescent tracers into M1 sites identified by intracortical microstimulation. In some of the same animals, the extent and somatotopic organization of M1 was determined by making detailed microstimulation movement maps and relating the results to cortical architectonics. Thus, delineation of M1 was based on a combination of physiological and anatomical characteristics. M1 comprised most, but not all, of the cortex rostral to area 3a where movements were evoked at low levels of current (40 μA or less). Analysis of somatotopic patterns and architectonics placed some of the low‐threshold sites in a ventral premotor field (PMV) and the dorsomedially situated supplementary motor area (SMA). Movements were also reliably elicited from a dorsal premotor area (PMD) at higher currents. M1 was characterized by a somatotopic global organization, representing hindlimb, trunk, forelimb, and face movements in a mediolateral sequence, and a mosaic local organization, with a given movement typically represented at several different sites. Architectionically, M1 was characterized by the absence of a granular layer IV and the presence of very large layer V pyramidal cells. However, M1 was not uniform in structure: pyramidal cells were larger caudally than rostrally, a feature we used to distinguish caudal (M1c) and rostral (M1r) subdivisions of the area. M1 resembles Brodmann's area 4, although the rostral subdivision has probably been considered as part of area 6 by some workers. Tracer injections of M1 revealed somatotopically distributed connections with motor areas PMD, PMV, and SMA, as well as in somatosensory areas 3a, 1, 2, and S2. Weaker connections were with area 3b, posterior parietal cortex, the parietal ventral area (PV), and cingulate cortex. M1r and M1c differed connectionally as well as architectonically, M1c being connected primarily with somatosensory areas, while M1r was strongly connected with both non‐primary motor cortex and somatosensory cortex. These results indicate that M1 interacts directly with at least three non‐primary motor areas and at least six somatosenso

ISSN:0092-7317    

DOI:10.1002/cne.903300207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractN‐Acetylaspartylglutamate (NAAG) is an endogenous brain dipeptide that satisfies many of the criteria for a neurotransmitter. We have previously identified NAAG immunoreactivity in neurons of the lateral geniculate nucleus (LGN) of the cat and monkey. To determine whether all LGN neurons contain NAAG, we treated sections of cat LGN with affinity‐purified antibodies to NAAG and counterstained them with thionin. The larger neurons contained NAAG, but the smaller neurons did not. We treated other sections with antiserum to glutamic acid decarboxylase (GAD), the rate‐limiting enzyme in the synthesis of γ‐aminobutyric acid (GABA), in order to label interneurons of the LGN. In these sections, the smaller cells were labeled; the larger neurons were not. We hypothesized that NAAG was present in relay cells, but not interneurons. We used two double‐labeling paradigms to test this hypothesis. We combined immunocytochemistry for NAAG using a fluorescent secondary antibody with either (1) fluorescent retrograde tracers (true blue, granular blue, rhodamine beads, or propidium iodide) injected into areas 17 and/or 18 or (2) immunocytochemistry for GAD using a second fluorescent secondary antibody. In the LGN, over 99% of retrogradely labeled cells contained NAAG, but few GAD‐positive neurons did. In contrast, neurons of the perigeniculate nucleus contained both NAAG and GAD, demonstrating that staining by one set of antisera did not inhibit staining by the other and that perigeniculate neurons are chemically distinct from the interneurons of the LGN. We conclude that in LGN, the relay cells, which project to visual cortex, contain NAAG, whereas most of the interneurons, which contain

ISSN:0092-7317    

DOI:10.1002/cne.903300208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractEfferents from the frontal eye fields (FEF) to the ipsilateral frontal lobe were studied by autoradiography of tritiated tracers (leucine, proline, and fucose) in seven macaque monkeys that were used previously to describe subcortical connections. In four of the cases, tracer injection sites were confirmed by low thresholds for the electrical elicitation of saccadic eye movements. Cases were grouped as lFEF or sFEF cases according to large or small saccades that were characteristic of the injection site.Projections from the FEF terminated in five frontal regions: (1) area FD on the dorsomedial convexity; (2) area FC (containing SEF) medial to the upper limb of the arcuate sulcus; (3) areas FD and FDΔ along the walls of the principal sulcus; (4) area FCBm on the deep, posterior wall of the arcuate sulcus inferior to the sulcal spur; and (5) the inferolateral cortex (area FDi) on the convexity and lateral two thirds of the anterior wall of the arcuate sulcus. Projections in sFEF cases tended to be confined to medial parts of dorsomedial FD and FC and the lateral wall of the principal sulcus and inferolateral convexity. Neither lFEF nor sFEF appeared to project to the SMA or pericingulate cortex. Label in these areas was found only in the cases in which tracer spread into non‐FEF areas.FEF projections terminated in column‐like patches of about 500–600 μm in diameter. Labeled axons and terminals were seen in all cortical layers regardless of location in the front

ISSN:0092-7317    

DOI:10.1002/cne.903300209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903300201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY