摘要:

AbstractThe organization of the inferior pulvinar complex (PI) in squirrel monkeys was studied with histochemical localization of the calcium binding proteins calbindin‐D28k and parvalbumin, and of cytochrome oxidase. With each of these markers, the inferior pulvinar complex can be subdivided into four distinct regions. Calbindin‐D28k immunoreactivity is densely distributed in cells and neuropil within PI, except for a distinct centromedially located gap. This calbindin‐poor zone, termed the medial division of the inferior pulvinar (PIM), corresponds precisely to a region that contains elevated cytochrome oxidase activity and parvalbumin immunostaining. The PIMextends slightly above and behind the classically defined limit of the inferior pulvinar, the corticotectal tract. Regions of inferior pulvinar with intense immunostaining for calbindin‐D28k were the posterior division of the inferior pulvinar (PIP, medial to PIM) and the central division (PIC, lateral to PIM). A newly recognized lateral region, PIL, adjoins the lateral geniculate nucleus and stains more lightly for calbindin and parvalbumin immunoreactivity and for cytochrome oxidase. Staining patterns for calbindin, parvalbumin, and cytochrome oxidase in the pulvinar of rhesus monkeys closely resemble those shown in squirrel monkey inferior pulvinar, suggesting that a common organization exists in all primates.In order to examine cortical connection patterns of the histochemically defined compartments in the inferior pulvinar, injections of up to five neuroanatomical tracers (wheat germ agglutinin conjugated to horseradish peroxidase and fluorescent retrograde tracers) were placed in the same cerebral hemisphere. Single injection sites were in the middle temporal area (MT), and several separate injections were placed in a strip corresponding to the rostral subdivision of the dorsolateral area (DLr). Injections that involved only DLr and not MT labeled principally the PIC, and more sparsely PIPand PIL. DLr connections occupied a „shell”︁ region dorsal to PIMthat extended from PICinto the lateral and medial divisions of the pulvinar, PL and PM. Injection sites that included MT or were largely restricted to MT produced dense label in PIMand moderate label in PICand PIL.The retinotopic organization within the inferior pulvinar was inferred from patterns of connections. Connections with cortex related most closely to central vision were found posteriorly in PIMand in adjacent portions of PICas it wraps around the caudal pole of PIM. Cortex related to more peripheral locations in the lower visual field connected with more rostral PIMand PIC. Patterns of label within the portions of PL and PM that were immediately adjacent to PIMroughly paralleled those in PIMand PIC. Thus, a distinct chemoarchitectonic subdivision of the inferior pulvinar, PIM, is the major source of thalamic projections to MT in squirrel monkeys. Interestingly, the relative scarcity of calbindin immunostaining in PIMis characteristic of „primary”︁ thalamic relay nuclei, such as the ventroposterior and lateral geniculate nuclei. Thus, the PIM‐MT pathway may share certain physiological charcteristics with primary sensory relays, such as those involving intracelluarl calcium buffering and, perhaps, rapid and secure impulse transmission.

ISSN:0092-7317    

DOI:10.1002/cne.903360102

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractGalanin immunoreactivity (GAL‐ir) is differentially expressed within the basal forebrain of monkeys and humans. Most monkey magnocellular basal forebrain neurons colocalize GAL‐ir. In contrast, virtually no human magnocellular basal forebrain neurons express GAL‐ir. Rather, an extrinsic galaninergic fiber plexus innervates these neurons in humans. The present study examined the expression of GAL‐ir within the basal forebrain of apes to establish the phylogenetic level at which this transformation occurs. The staining patterns of GAL‐ir within the basal forebrain of both lesser (gibbons) and great (chimpanzee and gorilla) apes were compared to that previously observed within monkeys and humans. All apes displayed a pattern of basal forebrain GAL‐ir indistinguishable from humans. GAL‐ir was not expressed within ape basal forebrain magnocellular neurons as seen in monkeys. Rather like humans, a dense collection of GAL‐ir fibers was seen in close apposition to magnocellular perikarya. In addition, a few GAL‐ir parvicellular neurons were scattered within the ape basal forebrain. These data indicate that the evolutionary change in the expression of GAL‐ir within the primate basal forebrain occurs at the branch point of monkeys and apes. ©

ISSN:0092-7317    

DOI:10.1002/cne.903360103

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractCholecystokinin (CCK) is now recognized as one of the most abundant peptides in the mammalian central nervous system. We have previously used immunohistochemistry to localize CCK in the adult and developing Brazilian opossum brain. However, little is known about the distribution of CCK binding sites in the developing mammalian brain. Therefore, to further our knowledge of the sites of action for CCK during development, we initiated a series of studies to localize CCK binding sites in the adult and developing Brazilian opossum. This species was chosen because pups are born in a fetus‐like state. Receptor autoradiography was performed on coronally sectioned brains of 1 to 60 day postnatal (PN) animals and adults with 125I‐Bolton Hunter‐CCK‐8 as the radioligand. Binding is evident in the 1PN opossum brainstem and is observed in the developing forebrain by 5PN. Region‐specific binding increases during development, and binding in the 35PN brain resembles the adult pattern. Binding is evident prior to the detection of CCK‐like immunoreactivity in many areas. The facial motor nucleus is identifiable and exhibits high levels of binding in Brazilian opossum pups of 10 to 35 days of age. However, binding is undetectable in the facial motor nucleus of 45 and 60PN pups. In general, the binding patterns for CCK in the adult opossum resemble those of other mammals and likely mediate similar physiological functions. However, some cholecystokininergic pathways appear to be unique to neonatal mammals. © 1993 Wil

ISSN:0092-7317    

DOI:10.1002/cne.903360104

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn order to determine whether neurones in the parvicellular reticular formation are in direct synaptic contact with motor neurones innervating masticatory muscles, a combined retrograde and anterograde transport study was carriedd out in the rat at both light and electron microscopic levels. The animals received injections of the retrograde tracers wheat germ agglutinin conjugated to horseradish peroxidase or cholera toxin B conjugated to horseradish peroxidase into the masticatory muscles and of the anterograde tracer biocytin into the ipsilateral parvicellular reticular formation. The trigeminal motor nucleus was then examined for both anterograde and retrograde labelling in the light and electron microscopes.Retrogradely labelled motor neurones were identified in the trigeminal motor nucleus. They were large and their locations within the nucleus depended on the muscle injected. In addition, terminals anterogradely labelled with the biocytin that was injected in the parvicellular reticular formation were identified throughout the motor nucleus. At the electron microscopic level, the retrogradely labelled cells were found to receive input both from distinct types of unlabelled terminals and from terminals that were anterogradely labelled from the parvicellular reticular formation. The labelled terminals comprised one of the four classes of afferent terminals, being 1–2 μm in diameter and densely packed with spherical vesicles. They formed mostly asymmetrical but also symmetrical synapses with the labelled perikarya and dendrites. Anterogradely labelled terminals were also observed to form both symmetrical and asymmetrical synaptic contacts with unlabelled structures in the motor nucleus.It is concluded that neurones in the parvicellular reticular formation form direct synaptic contact with motor neurones of masticatory muscles. This pathway may represent the anatmical substrate by which the reticular formation exerts at least part of its influence on mastication. Since the parvicellular reticular formation receives input from the substantia nigra pars reticulata, it is possible that this pathway represents a system whereby the basal ganglia directly influence orofacial movement. © 1993 Wiley‐Liss

ISSN:0092-7317    

DOI:10.1002/cne.903360105

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractMuscle spindles from the tenuissimus muscle of the cat were examined microscopically to assess the precision and completeness of reinnervation of intrafusal muscle fibers by efferent and afferent neurons. Positions of motor and sensory nerve terminals were charted relative to the cross‐sectional area enclosed by the outer capsule of the spindle. Profiles of nerve endings were measured for normally innervated and reinnervated spindles. The tenuissimus was deprivedof innervation by freezing its nerve, sometimes in conjunction with either spinal ganglion removal or ventral rhizotomy. Sensory and motor terminals occupied separate locales along the length of normal muscle spindles. Nerve terminals of efferent and afferent neurons were located in appropriate positions along the length of spindles when axons of both types of neurons regrew‐together and when either category of axon regenerated alone. Precise reinnervation of muscle spindles occurred in spite of a diminished diameter of intrafusal fibers. Repopulation of the spindle with motor endings was less complete than that by sensory endings, based on the proportion and size of the regenerated terminals. We conclude that under optimal conditions for axonal regrowth, efferent and afferent neurons reinnervate their respective regions along intrafusal muscle fibers but motor lags sensory reinnervation within the spindle. The mechanism by which positional specificity happens during reinnervation of intrafusal fibers requires neither an interaction between terminals of the two types of neurons nor target cells of normal bulk. © 1993 Wiley‐Lis

ISSN:0092-7317    

DOI:10.1002/cne.903360106

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractNADPH‐diaphorase histochemistry has been shown to be a useful method for identifying cells that synthesize and release nitric oxide, which is implicated in the modulation of a variety of neural functions, including synaptic transmission, cerebral blood flow, and excitotoxicity. In the sunfish brain, NADPH‐diaphorase histochemistry stains tanycytes specifically and almost exclusively, allowing for a thorough examination of the morphology and distribution of this type of cell. Tanycytes are nonciliated, process‐bearing ependymal and extraependymal cells that contact the ventricular surface via apical processes, and the pial surface via basal processes. Ependymal tanycytes are located at the ventricular surface, and project basal processes into the parenchyma of the brain. Extraependymal tanycytes are found away from the ventricular matrix. Some extraependymal tanycytes are small, bipolar, and tend to be associated with bundles of basal processes. Isolated extraependymal tanycytes are larger, darkly stained, and multipolar. Their basal processes terminate in specialized endfeet on blood vessels, neuronal somata, or the pial surface. Specialized types of tanycytes are found in the optic tectum, the epineurial septum between axonal bundles along the midline in the medulla, and in restricted regions on the pial surface in the medulla. The only NADPH‐diaphorase‐positive neurons are found in the commissural nucleus of area ventralis telencephali. Injection of horseradish peroxidase into the ventricles shows that tanycytes lining the third and fourth ventricles are capable of taking up the tracer and transporting it into their basal processes.Tanycytes are unevenly distributed in the brain. There is a rough rostrocaudal gradient of cell density: tanycytes are sparse in the telencephalon and dense in the isthmus and medulla, although cell density is low in the spinal cord. Not all ventricular linings contain tanycytes: cell density is low in the medial ventricle of the telencephalon and in the infundibular recess, and high along the fourth ventricle.The function of tanycytes in the sunfish is not known. The association of tanycytes with both the ventricles and blood vessels raises the possibility that they play some role in sampling the biochemical constituents of both compartments and communicating the information to neural elements. It is proposed that tanycytes react to the biochemical composition in the ventrile and plasma by increasing or decreasing nitric oxide synthesis and release, which in turn influence neuronal activity or cerebral blood flow. © 1993 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903360107

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe hypothesis that sacrocaudal dorsal horn neurons with crossed receptive field components on the tail have dendrites which cross to the contralateral dorsal horn was tested in a combined electrophysiological and morphological study. Dorsal horn cells in the sacrocaudal spinal cord of anesthetized cats were penetrated with horseradish peroxidase‐filled microelectrodes. After mapping their low threshold mechanoreceptive fields, cells were iontophoretically injected with horseradish peroxidase.A sample of 16 well‐stained cells was obtained in laminae III and IV. Cells with receptive fields crossing the dorsal midline of the tail (n ‐ 8) had somata in the lateral ipsilateral dorsal horn, and some of these cells (5/8) had dendrites which crossed to the lateral contralateral dorsal horn. Cells with receptive fields spanning the ventral midline (n ‐ 2) were located near the center of the fused dorsal horn, and one of these had bilateral dendrites in this region. Cells with receptive fields on the lateral tail, crossing neither the dorsal nor the ventral midline (n ‐ 6), had cell bodies in the middle of the ipsilateral dorsal horn; half had only ipsilateral dendrites, and half had crossed dendritic branches.Although the relationship between cell receptive field (RF) location (RF center, expressed as distance from tips of toes) and mediolateral location of the cell body was statistically significant, the correlation between crossed RF components and crossed dendritic branches was not significant. © 1993 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903360108

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractA model that has been widely used in the study of steroid sensitive neurons, the spinal nucleus of the bulbocavernosus (SNB) is a sexually dimorphic motor nucleus in the lower lumbar spinal cord that innervates the striated bulbocavernosus (BC) muscle. The BC is responsible for penile reflexes in the male rat, which are important in ensuring pregnancy in females. The characterization of afferents to the SNB aids in the understanding of the neural circuitry involved in reproductive behavior. We have recently identified the paraventricular nucleus (PVN) as a possible source of afferents to the SNB. Because the PVN is the major source of oxytocin/vasopressin within the central nervous system (CNS), the purpose of the present study was to examine and characterize a neurophysin (NP)‐containing pathway from the PVN to the SNB. The results demonstrate that neurons of the lateral parvicellular subnucleus of PVN, which project to levels of spinal cord containing SNB motoneurons, contain NP, the coproduct of oxytocin and vasopressin. NP‐containing fibers and putative terminals were found in the region of the SNB and appear to contact the soma and proximal dendrites of SNB motoneurons which were retrogradely identified as BC‐innervating. Electrolytic lesions, which destroy the lateral parvicellular subnucleus of PVN, abolish NP‐containing fibers in the region of the SNB, suggesting that the PVN is the source of these NP fibers. The results of this study indicate a NP‐containing projection from the hypothalamus directly to SNB motoneurons. It is suggested that this pathway may play a role in the integration of penile reflexes with other aspects of male copulatory behavior that are under hypothalamic control. © 1993 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903360109

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe cholinergic innervation of the human amygdaloid complex was studied immunohistochemically with a choline acetyltransferase (ChAT) antibody in eight brains: five control and three with Alzheimer's disease (AD). All amygdaloid nuclei displayed ChAT‐immunopositive axons and varicosities. The density of these axons reached levels that were higher than in any other part of the forebrain except for the striatum. The highest level of ChAT‐immunopositive profiles was seen in the basolateral nucleus and the second highest in the lateral part of the central nucleus. The basomedial, accessory basal, and cortical nuclei, the amygdalohippocampal and cortico‐amygdaloid transition areas, as well as the anterior amygdaloid area, showed a moderate density of ChAT‐positive varicosities and fibers. The lateral nucleus displayed a relatively low density of cholinergic innervation, and there were only rare ChAT‐positive fibers in the medial nucleus. Although the level of cholinergic innervation in the lateral nucleus was relatively lower than in many of the other amygdaloid nuclei, it was approximately equivalent to that of entorhinal cortex, a region that receives one of the heaviest cholinergic inputs in the cerebral cortex. The distribution of the cholinergic fibers as studied by ChAT immunohistochemistry was nearly identical to that observed with AChE histochemistry. Quantitative densitometry in control specimens showed that there was no decline of amygdaloid cholinergic input when middle‐aged subjects were compared with senescent subjects. In AD there was a severe and regionally selective depletion of this innervation in the amygdaloid complex. The cortical, accessory basal, and lateral nuclei displayed the most severe loss of ChAT‐positive profiles, whereas the basolateral, and especially the central, nuclei displayed relatively little change. There was no consistent relationship between the loss of cholinergic fibers and the density of amyloid plaques and neurofibrillary tangles in amygdaloid nuclei. © 1993 W

ISSN:0092-7317    

DOI:10.1002/cne.903360110

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study describes the architecture of neurons and individual dendritic arbors of thirteen intracellularly labeled thalamocortical projection neurons that respond to non‐noxious stimuli from the primate (Macaca fascicularis or Macaca mulatta) ventrobasal complex (VB). The neurons compose a homogeneous morphological class with total dendritic lengths from 10,169 μm to 21,711 μm (mean 17,615 μm ± 3,705). The labeled neurons were remarkably similar in most measured parameters including the number of dendrites (7.5 ± 1.2), percentage of dichotomous branching (89.8% ± 3.4), and contribution of terminal branches to total dendritic length (88.4% ± 2.0).The individual dendrites ranged in total length from 443 μm to 7,657 μm with a mean of 2,346 μm (±137, n = 98). There was a positive correlation between stem dendrite diameter and total dendrite length, making it possible to estimate the total size of an individual dendrite by measuring the stem dendrite diameter. There was only a small increase in mean path distance with increasing dendritic size at the whole neuron and individual dendritic levels, so that for individual dendrites the mean path distance of a dendrite consisting of only two segments was 199 μ, while the mean path distance for a dendrite with eight segments was only 45 μm longer. Analysis of dendrite diameter, segment order, and path distance shows that dendritic diameter is not reliable for determining the location of synaptic contacts viewed by electron microscopy onto dendritic trees. The small variation of measured parameters between these neurons presents a powerful tool for future developmental, plasticity and comparative studies of VB neurons. © 1993

ISSN:0092-7317    

DOI:10.1002/cne.903360111

出版商:Wiley‐Liss, Inc.    

年代:1993

数据来源: WILEY