摘要:

AbstractNeuronal morphology was analyzed in the pars compacta, reticulata, and lateralis of the substantia nigra of humans and macaques. Golgi‐impregnated dendritic arborizations, reconstructed from serial sections, were described by using topological, metrical, and geometrical parameters measured in three dimensions. Morphological parameters were statistically analyzed. Cell bodies and axons were also described.The primate substantia nigra comprises few local circuit microneurons. It consists mainly of large projection neurons having large cell bodies and sparsely branched dendritic arborizations. In all subdivisions, “complex endings” and “thin processes” can be found on nigral dendrites. Axons of large neurons occasionally had initial collaterals that never form profuse arborizations. Pars reticulata neurons had a cell body surface of 520 μm2, 4 dendritic stems, and 13 dendritic tips. The total dendritic length (L) was 7,100 μm, the highest dendritic length (Lm) 1,200 μm, and the mean length of dendritic segments 320 μm. Pars lateralis neurons were similar except for their larger cell bodies (650 μm2) and longer dendritic segments (440 μm). Pars compacta neurons had larger cell bodies (860 μm2), thicker and more numerous (5 stems, 19 tips), and longer dendrites (L = 10,500 μm; Lm = 1,400 μm). Large neurons of monkeys had the same topological characteristics as human neurons but shorter dendrites. The overall shape of arborizations was highly variable and not characteristic in any subdivision.A hierarchical typology of nigral neurons is proposed, which comprises two neuronal species, the compacta and reticulata species, and a lateralis subspecies. Pallidal neurons (Yelnik et al., '84) belong to the reticulata species. The position of these species in relation to higher hierarchical l

ISSN:0092-7317    

DOI:10.1002/cne.902650402

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe spatial organization of Golgi‐stained dendritic arborizations of the substantia nigra was studied in three dimensions by using a video computer system. Dendritic orientation was analyzed in relation to the cytoarchitectonic boundaries and to the direction of the axons of the striato‐pallidonigral bundle. All the brains, humans and macaques, were sectioned according to the same ventricular planes. The striatal bundle is made up of dense fascicles of very thin parallel axons. Sixty neurons located in the pars reticulata, lateralis, and compacta were reconstructed from serial sections. In the anterior pars reticulata and lateralis, the dendritic arborizations spread in all directions inside the striatal bundle. Below the pars compacta fringes, the dendrites of pars reticulata neurons extend ventrolaterally in the bundle. Because one nigral arborization can cover the whole thickness of the striatal bundle, we are led to believe that nigral neurons exert a role of convergence of the corticostriatal information similar to that of pallidal neurons (Percheron et al., '84a,b). The pars reticulata neurons appear to receive information mainly from the associative striatal territory. The pars lateralis neurons, conversely, appear to receive information from the sensorimotor territory. The anterior pars compacta neurons are organized in such a way that their ventral dendrites, located inside the pars reticulata, are ventrolaterally oriented, perpendicular to the striatal bundle. Their dorsal dendrites remaining in the pars compacta can receive other input. At more caudal levels, the posterior pars compacta neurons have dendrites radiating outside the striatal bun

ISSN:0092-7317    

DOI:10.1002/cne.902650403

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

年代:1987

数据来源: WILEY

摘要:

AbstractNeurons that provide the efferent innervation to the labyrinthine and lateral line sense organs of the eel were located by applying horseradish peroxidase to branches of the appropriate cranial nerves. Retrogradely labeled neurons were found in a single median column, the octavolateralis efferent nucleus (OEN), located immediately rostral to and overlapping with the facial nucleus of the branchiomotor column. We estimate that on each side of the brain the efferent nucleus contains about 60–70 neurons, most of which supply the ear and the lateral line system of the head. Most neurons (∼90%) are ipsilateral to the targets they innervate. There is no crisp topographical order within the nucleus because neurons supplying different end organs intermingle. However, the head lateral line is supplied by rostrally located neurons, and the body system by more caudal neurons.There are no marked differences in cell form between neurons supplying different targets. Most are multipolar, relatively uniform in size, and have extensive dendrites. The dendrites of some cells extend to the contralateral side of the brain. Efferent axons are of small diameter (∼3 μm). Two neurons are sufficiently constant in size and location that they can be consistently recognized from fish to fish. Their axons branch to supply more than one target. Nearly all efferent neurons stain for acetylcholinesterase and some, bordering the midline, consistently stain

ISSN:0092-7317    

DOI:10.1002/cne.902650404

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

年代:1987

数据来源: WILEY

摘要:

AbstractSensory nerve fibers from the lateral line system and labyrinth ofAnguilla anguillawere labeled with horseradish peroxidase and traced to various targets in the ipsilateral brainstem.The three rami of the anterior lateral line nerve and the supratemporal ramus of the posterior lateral line nerve form overlapping terminal zones in the ventral portion of nucleus medialis. The posterior lateral line nerve on the body is represented exclusively in the dorsal half of the nucleus medialis. Eighth nerve fibers from the otolithic end organs in the inner ear send fibers into dorsal portions of three octavus nuclei: anterior, magnocellular, and descending, and saccular fibers lie most medial and utricular fibers most lateral. Fibers from vestibular organs, especially the semicircular canals and utricle, end densely in ventral portions of these nuclei and in the tangential nucleus. All labyrinthine sense organs send fibers into the region of a Mauthner‐like neuron, and all except the saccule terminate in the reticular formation, tangential nucleus, and eminentia granularis of the cerebellum. Primary sensory input to the octavolateralis efferent nucleus comes only from the labyrinth, and fibers from the saccule alone penetrate the region of efferent neuronal somata. Fibers from labyrinthine end organs except the saccule project to the reticular formation where they may contact the dendrites of efferent somata. Fibers from the lateral line and the eighth nerve overlap most extensively at the rostral pole of the nucleus medialis and in the eminentia granularis of the cerebellu

ISSN:0092-7317    

DOI:10.1002/cne.902650405

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution of muscarinic and benzodiazepine receptors was investigated in the turtle forebrain by the technique ofin vitroreceptor autoradiography. Muscarinic binding sites were labeled with 1 nM3H‐quinuclidinyl benzilate (3H‐QNB), and benzodiazepine sites were demonstrated with the aid of 1 nM3H‐flunitrazepam (3H‐FLU). Autoradiograms generated on3H‐Ultrofilm apposed to tissue slices revealed regionally specific distributions of muscarinic and benzodiazepine binding sites that are comparable with those for mammalian brain. Dense benzodiazepine binding was found in the anterior olfactory nucleus, the lateral and dorsal cortices, and the dorsal ventricular ridge (DVR), a structure with no clear mammalian homologue. Muscarinic binding sites were most dense in the striatum, accumbens, DVR, lateral geniculate, and the anterior olfactory nucleus.Cortical binding sites were studied in greater detail by quantitative analysis of autoradiograms generated by using emulsion‐coated coverslips. Laminar gradients of binding were observed that were specific for each radioligand;3H‐QNB sites were most dense in the inner molecular layer in all cortical regions, whereas3H‐FLU binding was generally most concentrated in the outer molecular layer and was least dense through all layers in the dorsomedial cortex. Because pyramidal cells are arranged in register in turtle cortex, the laminar patterns of receptor binding may reflect different receptor density gradients along pyramidal

ISSN:0092-7317    

DOI:10.1002/cne.902650406

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution of dopamine‐containing cell somata and fibers in the forebrain and midbrain of a cartilaginous fish,Raja radiata, was investigated by means of antibodies directed against dopamine. Many small dopamine immunoreactive neurons are distributed throughout the telencephalon, including the olfactory bulbs. Within the diencephalon and particularly in the hypothalamus, i.e., in the nucleus preopticus, nucleus suprachiasmaticus, the paraventricular organ, lateral hypothalamic area, recessus mamillaris, and nucleus tuberculi posterioris, numerous cell somata stain for dopamine. In the mesencephalon, two distinct cell masses are found, which on the basis of their immunoreactivity for dopamine and their location, may be homologous to the substantia nigra and ventral tegmental area of other vertebrates, Dopamine immunoreactive fibers are found in the glomeruli of the olfactory bulbs, in ventral portions of the telencephalon, where a dense dopaminergic plexus innervates the area superficialis basalis and striatum, and in the diencephalon, where the inferior lobe is the most densely innervated structure. In the mesencephalon, the dopamine immunoreactive fibers are confined predominantly to the periventricular zone and lateral portions of the tectum.We conclude that much of the dopaminergic system inRaja radiatais strikingly similar to that seen in amniote

ISSN:0092-7317    

DOI:10.1002/cne.902650407

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe anatomical tracer, wheat germ agglutinin, was used to determine the connections of electrophysiologically identified locations in three architectonically distinct representations of the body surface in the somatosensory cortex of gray squirrels. Injections in the first somatosensory area, S‐I, revealed reciprocal connections with the ventroposterior nucleus (VP), a portion of the thalamus just dorsomedial to VP, the posterior medial nucleus, Pom, and sometimes the ventroposterior inferior nucleus (VPI). As expected, injections in the representation of the face in S‐I resulted in label in ventroposterior medial (VPM), the medial subnucleus of VP, whereas injections in the representation of the body labeled ventroposterior lateral (VPL), the lateral subnucleus of VP. Furthermore, there was evidence from connections that the caudal face and head are represented dorsolaterally in VPM, and the forelimb is represented centrally and medially in VPL. The results also support the conclusion that a representation paralleling that in VP exists in Pom, so that the ventrolateral part of Pom represents the face and the dorsomedial part of Pom is devoted to the body. Because connections with VPI were not consistently revealed, the possibility exists that only some parts or functional modules of S‐I are interconnected with VPI.Two separate small representations of the body surface adjoin the caudoventral border of S‐I. Both resemble the second somatosensory area, S‐II, enough to be identified as S‐II in the absence of evidence for the other. We term the more dorsal of the two fields S‐II because it was previously defined as S‐II in squirrels (Nelson et al., '79), and because it more closely resembles the S‐II identified in most other mammals. We refer to the other field as the parietal ventral area, PV (Krubitzer et al., '86). Injections in S‐II revealed reciprocal connections with VP, Pom, and a thalamic region lateral and caudal to Pom and dorsal to VP, the posterior lateral nucleus, Pol. Whereas major interconnections between S‐II and VPI have been reported for cats, raccoons, and monkeys, no such interconnections were found for S‐II in squirrels. The parietal ventral area, PV, was found to have prominent reciprocal interconnections with VP, VPI, and the internal (magnocellular) division of the medial geniculate complex (MGi). The pattern of connections conforms to the established somatotopic organization of VP and suggests a crude parallel somatotopic organization in VPI. Less prominent interconnections were with Pol. Sparse, fine label in part of the ventral (principal) nucleus of the medial geniculate complex (MGv) suggests the existence of some input from PV.The connections demonstrated in the present study help characterize three somatosensory areas in squirrels. Such information is essential for identifying homologous areas of cortex across species, and several possibilities are outlined in the Discussion. In addition to VP, the results suggest the presence of two somatic nuclei, the medial and lateral nucleus of the Po group; and evidence is provided for the existence of VPI in rodents. Furthermore, consistent with many recent reports, we found that each cortical area has interconnections with more than one thalamic nuclei, and each thalamic nucleus has interconnections with more than one cortical field. Finally, in keeping with the responsiveness of neurons in PV to both somatic and auditory stimuli (Krubitzer et al., '86), PV was found to have interconnections with both somatic and a

ISSN:0092-7317    

DOI:10.1002/cne.902650408

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution of catecholaminergic and cholinergic neurons in the upper brainstem of the ferret were mapped by staining immunohistochemically two adjacent series of sections of brainstem for tyrosine hydroxylase and choline acetyltransferase, respectively. As in other species, large numbers of tyrosine‐hydroxylase‐positive neurons are localized in the ventral tegmental area (A10), the substantia nigra (A9), and in A8. Tyrosine‐hydroxylase‐positive neurons in the dorsolateral pontine tegmentum (A4, A6, and A7‐the locus coeruleus complex) of the ferret are rather diffusely distributed, as has been observed in other carnivore species such as the cat and the dog, but unlike in the cat, these cells in the ferret display a relative uniformity in size and morphology.Choline‐acetyltransferase‐positive neurons which extend in the ferret's pedunculopontine tegmental nucleus and ventral parabrachial area (Ch5) are relatively large cells that stain intensely for choline acetyltransferase, and their dendrites form prominent bundles in regions where unstained fibre tracts are prevalent. Choline‐acetyltransferase‐positive neurons distributed in the laterodorsal tegmental nucleus (Ch6) are smaller than the cholinergic cells of Ch5, and they stain less intensely for choline acetyltransferase.Rostrally, there is little overlap between the catecholaminergic cell groups A8, A9, and A10 and the cholinergic cell groups of Ch5 and Ch6. Caudally, the Ch5 neurons extend some considerable extent into the locus coeruleus complex. In the region of overlap, no cells with staining for both tyrosine hydroxylase and choline acetyltransferase were observed, as was ascertained with a double staining method employing a combination of tyrosine hydroxylase immunofluorescence and choline acetyltransferase peroxidase‐antiperoxidase immunohistochemistry.In conclusion, the ferret has a typically carnivore pattern for the distribution of catecholaminergic cells in the upper brainstem, and there is a significant overlap between the catecholaminergic and cholinergic cell groups in the dorsolatera

ISSN:0092-7317    

DOI:10.1002/cne.902650409

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

年代:1987

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902650401

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

年代:1987

数据来源: WILEY