摘要:

AbstractThe organization of indoleamine‐containing neurons throughout the CNS ofMacaca mulattawas examined with Falck‐Hillarp histofluorescnce and radioenzymatic biochemical techniques. Indoleamine‐containing cell bodies, corresponding to the serotonin‐containing groups B1 to B9, were observed within the brain stem. The pontine cell populations, however, were far more numerous than in the rat and represented caudal subpopulations of cells within the nucleus raphe dorsalis (B7) and nucleus centralis superior (B8). Additionally, the pontine indoleamine‐containing cells inM. mulattaextended laterally through the tegmentum such that they were often adjacent to catecholamine‐containing neurons of the locus coeruleus complex. Ascending indolaemine‐containing fiber bundles, similar to those defined in nonprimate mammals, were also observed within the pons and mesencephalon.Regional differences in the distribution of serotonin within hypothalamic nuclei and other forebrain regions ofM. mulattawere revealed through a highly sensitive radioenzymatic assay in conjunction with microdissection. Significant concentrations of serotonin were evident in most areas, although the levels of this neurotransmitter were much lower in the median eminence region and nucleus suprachiasmaticus than in the rat. These differences may reflect variations in the control of neuroendocrine events in th

ISSN:0092-7317    

DOI:10.1002/cne.901970302

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

年代:1981

数据来源: WILEY

摘要:

AbstractIn the sensory epithelium (macula) of the gravity receptor system of the statocyst ofOctopus vulgaris, there are two types of afferent neurons, distinguished according to their position in the epithelium. The somata of one type lie accumulated in a ring peripheral to the hair cell layer of the epithelium; these are disignated asperimacularneurons. The somata of the other type lie among the hair cells, below the level of their nuclei; these are designated asintramacularneurons. Axons of afferent neurons which touch the hair cells are postsynaptic to some of the hair cells touched. As the somata of the intramacular neurons also touch the hair cells, they were investigated by serial electron microscopic reconstruction to determine if afferent synaptic contacts between hair cells and these somata occur.An average of about 600 intramacular neurons was counted in two maculae. Afferent synapses were seen to occur between hair cells and the somata of 76% of the intramacular neurons investigated. The postsynaptic processes of the intramacular neurons' somata were of two morphological types; one with a finger‐like and one with a flat postsynaptic process (average of one synapse of each type per soma). The soma of an intramacular neuron can be postsynaptic to more than one hair cell simultaneously (average of 1–2 hair cells per soma). In addition to being presynaptic to only one neuron's soma, a hair cell could be simultaneously presynaptic to the axons of one or more afferent neurons. The morphological findings are discussed as to their possible physiological consequen

ISSN:0092-7317    

DOI:10.1002/cne.901970303

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe three‐dimensional distribution of dendrites from the dorsal neck muscles biventer cervicis (BC) and complexus (CM) was examined in the adult cat using intracellular staining techniques. Motoneurons were electrophysiologically identified, stained with injection of horseradish peroxidase, and reconstructurcted from serial histological sections. The dendritic distributions of all motoneurons examined followed an orderly pattern. Many dendrites extended rostrally and caudally to form a complex parallel collection of dendrites in the ventromedial nucleus. Other dendrites projected dorsolaterally into the spinal accessory nucleus and lateral parts of lamina VII and VIII. Dorsomedial dendrites followed a path parallel to the medial border of the ventral horn and frequently terminated near the central canal. A few scattered dendrites were usually found directly dorsal to the soma in lamina VIII.This pattern of dendritic distribution differed distinctly from the dendritic distribution of motoneurons in other spinal regions. However, in all spinal regions, including the upper cervical spinal cord where BC and CM motoneurons were found, the pattern of dendritic distribution from different motoneurons was similar if their somata were located in the same region.For 15 motoneurons with well‐stained dendrites, the mean rostral‐caudal extent of the dendritic tree was 2,860 μm. The mean total dendritic length of three of these motoneurons measured 73,100 μm, almost four times larger than hindlimb motoneurons involved in planter reflexes. Despite the large size of the dendritic trees of BC and CM motoneurons, the surface areas of BC and CM cell bodies were smaller than most large hindlimb motoneurons. These quantitative differences in motoneuron dimensions may in turn be reflected by differences in the electrotonic properties of motoneurons in different motoneuron

ISSN:0092-7317    

DOI:10.1002/cne.901970304

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

年代:1981

数据来源: WILEY

摘要:

AbstractSpinocerebellar tract (SCT) neurons projecting to lobules I and II of the cerebellar anterior lobe were identified by the retrograde horseradish peroxidase technique in the cat. Instead of a conventional stereotaxic approach, we removed ventral parts of the vermis of the posterior lobe and approached the posterior aspect of lobule I through the fourth ventricle. Under direct visual guidance, discrete injections were made into lobule I or lobule II with a glass micropipette.Neurons projecting to lobule I were located mainly in the central cervical nucleus (CCN), the medial part of lamina VII of L6 to the caudal segments, and in lamina VIII of S2 to the caudal segments (with crossed ascending axons). The latter two groups correspond to the medial lamina VII group of the lumbar to the caudal segments and the ventral horn group of the sacral‐caudal segments of our previous studies. A small number of Clarke column neurons (with uncrossed ascending axons) also projected to lobule I. All of these neuronal groups projected to lobule II. In addition, large neurons in lamina V and in the border between laminae IV and V from S2 to the caudal segments projected to sublobule IIA, and more numerously to sublobule IIB (with crossed ascending axons). They belong to the dorsal horn group of the sacral‐caudal segments of our previous studies. Spinal border cells (with crossed ascending axons) projected to sublobule IIB, and a small number, to sublobule IIA. It was suggested that the CCN neurons project more densely to the median region whereas Clarke column neurons project to the lateral part of these lobu

ISSN:0092-7317    

DOI:10.1002/cne.901970305

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

年代:1981

数据来源: WILEY

摘要:

AbstractElectrophysiological methods were employed to determine whether or not partial visual cortical lesions in neonatal (7–11‐day) hamsters produced large scotomas in the cortical visual representation. In cases where such scotomas were present electrophoretic deposits of radioactive amino acids in the visually responsive “cortical remnant” of the damaged hemisphere resulted in labeling throughout the lower portion of thestratum griseum superficialeand thestratum opticumof the ipsilateral superior colliculus. No differential labeling of the part of the colliculus which was topographically matched with the remaining visual representation in the cortical remnant was observed. In normal hamsters relatively localized, visual cortical deposits of radioactive amino acids resulted in superficial layer labeling only in portions of the colliculus which corresponded to the locus of the cortical deposit.In a similar fashion, small lesions at physiologically defined loci in the cortical remnant produced degeneration throughout most of the superficial tectal laminae, but a more restricted “focus” of denser degeneration was also visible in these cases. The position of this focus in the colliculus for a given cortical lesion varied with the nature of the visual map in the cortical remnant. In several additional neonatally brain‐damaged hamsters large lesions of the visual cortex in the intact hemisphere were combined with radioactive amino acid deposits in the cortical remnant to determine whether or not axons from the crossed corticocollicular pathway previously demonstrated in such hamsters were intermingled with fibers from the ipsilateral corticotectal projection. In alternate sections processed for autoradiography or by the Fink‐Heimer ('67) method autoradiographic label and degeneration argyrophilia were both observed in the medial part of the colliculus ipsilateral to the neonatal

ISSN:0092-7317    

DOI:10.1002/cne.901970306

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

年代:1981

数据来源: WILEY

摘要:

AbstractSingle unit recording from cells in the superior colliculus ipsilateral to the damaged hemisphere in hamsters subjected to unilateral removal of a part of the posterior neocortex during infancy was combined with electrical stimulation of the cortical remnant and the visual cortex in the undamaged hemisphere. Cells activated by stimulation of the cortical remnant were recorded in all portions of the colliculus. No differences in percentages of driven cells or threshold current intensities were noted between electrode penetrations in which collicular neurons having receptive fields within the remaining visual cortical representation were recorded and tracks where units with receptive fields outside this region were isolated. In the medial part of the tectum ipsilateral to the damaged hemisphere cells driven by stimulation of either cortex were encountered. It was also demonstrated that stimulation of the ipsilateral cortical remnant and/or the contralateral cortex was capable of suppressing discharges normally elicited by optic chiasm or visual stimulation in a manner qualitatively similar to that observed for collicular cells in normal hamsters. The response properties of cells functionally influenced by the ipsilateral and/or contralateral corticles were not different from those of neurons which received no demonstrable cortical input. The receptive field characteristics of the sample of neurons recorded were, on the whole, quite similar to those of collicular neurons in hamsters subjected to lesions of the visual cortex as adults.

ISSN:0092-7317    

DOI:10.1002/cne.901970307

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe organization of the lateral reticular nucleus (LRN) of the cat was investigated using electron microscopic and Golgi techniques. Golgi‐Cox preparations revealed that the LRN consists of allodendritic and, especially, isodendritic neurons. The latter have been associated with neural centres that have important roles integrating signals from distant sources. Several froms of spines were identified with the Golgi method, and their ultrastructural correlates were determined. Somatic spines resembled stubby protrusions, while dendritic spines, which were usually observed on distal dendrites, appeared as pedunculated spines, recemose appendages and spine‐crowned appendages.Ultrastructural exmaination of this nucleus revealed various synaptic relationships. The majority of the synaptic terminals were small (1.5–2.5 μm in diameter), contained round vesicles and usually contacted dendrites and spines. Other small terminals contained pleomorphic vesicles and contacted distal dendrites and spines. Large terminals (>2.5 μm in diameter) with round or pleomorphic vesicles contacted the somata or proximal dendrites. Three types of “synaptic configurations,” which consisted of discrete aggregations of neuronal processes invested by astrocytic lamellae, were also identified. These structural arrangements likely provide a basis for the integration of inputs to the LRN from spinal and supraspi

ISSN:0092-7317    

DOI:10.1002/cne.901970308

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe topographical organization of the projections to the lateral reticular nucleus (LRN) of the cat was investigated using the horseradish peroxidase (HRP), silver‐impregnation and autoradiographic tracing methods. Following injection of HRP into the LRN, labelled cells were found mainly within Rexed's laminae VII and VIII of the spinal cord, the contralateral red nucleus, the ventrorostral aspect of the contralateral fastigial nucleus and the contralateral anterior sigmoid and coronal gyri of the cerebral cortex. Animals with injections of tritiated amino acids placed within the pericruciate cortex, red nucleus or fastigial nucleus were processed for autoradiography. In a corresponding series of animals, electrolytic lesions were placed selectively into the above sources of reticular afferents, and terminal degeneration within the LRN was studied by light microscopy. An extensive input from the spinal cord was found to terminate predominantly on the ipsilateral side throughout the rostrocaudal extent of the LRN, except for a small ventromedial area of the rostral parvocellular division and a small rostromedial area of the magnocellular division. The cortical projection terminated diffusely within the middle one‐half of the contralateral magnocellular division, while the rubral projection terminated extensively within the contralateral subtrigeminal division and the dorsolateral region of the rostral magnocellular and neighbouring parvocellular divisions. The rubral projection did not overlap the cortical projection. The fastigial nucleus projected sparsely to the contralateral LRN, mainly to the medial aspect of the rostral two‐thirds of the magnocellular division, with less to the parvocellular and subtrigeminal divisions.The LRN therefore receives spinal and supraspinal projections within at least its rostral one‐half, and these terminate within specific areas in a partially overlapping fashion, whereas the caudal one‐half is primarily a spinal receiving region. No convergence of the rubral and sensorimotor cortical projections wa

ISSN:0092-7317    

DOI:10.1002/cne.901970309

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe mode and pattern of termination of the afferents to the lateral reticular nucleus (LRN) of the cat were examined at the cellular level through the ultrastructural localization of induced degeneration. Examination of the LRN following hemicordotomy at the fifth and sixth cervical levels revealed that most of the degenerating terminals were in contact with intermediate and distal dendrites, and that most of these degenerating terminals were small and contained round vesicles. Fewer degenerating terminals were observed on the somata and proximal dendrites after spinal hemisection, and most of these terminals were large and contained round vesicles. Following lesions of the pericruciate cortex, small degenerating terminals were occasionally observed making contact onto intermediate and distal dendrites. Degenerating rubral terminals were observed synapsing on somata, somatic and dendritic spines, proximal dendrites and most commonly on intermediate and distal dendrites following lesioning of the red nucleus. The degenerating axosomatic rubro‐LRN terminals belonged to the large, round‐vesicle terminal population, while those degenerating terminals contacting intermediate and distal dendrites belonged to the small, round‐vesicle population. Small, degenerating terminals were occasionally seen following lesions of the fastigial nucleus, and they made synaptic contact mainly onto intermediate and distal dendrites and dendritic spines.The present ultrastructural observations taken together with the convergence pattern of LRN afferents and the available electrophysiological data on inputs to the LRN suggest an extensive integration of converging impulses from two or more afferent sources to the rostral LRN neurons. The results of this study therefore support the view that the rostral LRN functions as a comparator of command signals from the motor cortex and red nucleus and feedback signals from the spinal cord and cerebellum during ongoing mov

ISSN:0092-7317    

DOI:10.1002/cne.901970310

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe dorsal lateral geniculate nucleus (dLGN) ofMacacamonkeys was studied by Golgi and quantitative electron microscopic (EM) methods to determine if differences in neuronal morphology exist which might correlate with the known physiological separation of X‐type cells into the parvocellular and Y‐type cells into the magnocellular laminae. Monocularly lid‐suturedMacacamonkeys were also studied by quantitative EM methods to compare the synaptic organization within laminae innervated by the deprived and nondeprived retinae.We have divided our sample of Golgi‐impregnated neurons into three groups: Types A, B, and C. Type A neurons comprise the majority of the projection cells and are quite heterogeneous in their overall morphology. Type B neurons have long dendrites with multiple appendages; some have a locally ramifying beaded axon. Type C neurons are characterized by dendrites which are mainly restricted to the interlaminar zones. We found Type A and B neurons in both the parvocellular and magnocellular laminae. The cell bodies of Type C neurons lay within the interlaminar zones or the parvocellular laminae. All three types contributed dendrites to the interlaminar zones. No significant differences in Golgi morphology other than overall size were found in parvocellular or magnocellular laminae that would explain the previously demonstrated electrophysiological differences.Terminal profiles and synapses in the parvocellular, magnocellular, and interlaminar zones were classified and counted using quantitative EM methods. RSD and F terminals were most numerous in all three zones. RLP terminals were rare in the interlaminar zones. A new type of terminal, RMD, was found in the magnocellular interlaminar zones. The laminar and interlaminar zones have the same overall synaptic density, but differed in types of synaptic terminals. The only quantitative difference between any of these regions was in the magnocellular laminae where the counts showed 70% more F terminals per unit area.The same quantitative methods were applied to the laminar and interlaminar zones of dLGNs from monocularly lid‐sutured monkeys. We found no qualitative or quantitative difference between the synaptology of zones receiving input from the deprived retina compared to the open eye retina, nor between any regions of the dLGN in deprived monkeys compared to norma

ISSN:0092-7317    

DOI:10.1002/cne.901970311

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

年代:1981

数据来源: WILEY