摘要:

AbstractThe ascending and descending projections of the parabrachial nuclear complex in the pigeon have been charted with autoradiographic and histochemical (WGA‐HRP) techniques.The ascending projections originate from a group of subnuclei surrounding various components of the brachium conjunctivum, namely, the superficial lateral, dorsolateral, dorsomedial, and ventromedial subnuclei. The projections are predominantly ipsilateral and travel in the quintofrontal tract. They are primarily to the medial and lateral hypothalamus (including the periventricular nucleus and the strata cellulare internum and externum), certain dorsal thalamic nuclei, the nucleus of the pallial commissure, the bed nucleus of the stria terminalis, the ventral paleostriatum, the olfactory tubercle, the nucleus accumbens, and a dorsolateral nucleus of the posterior archistriatum. There are weaker or more diffuse projections to the rostral locus coeruleus (cell group A8), the compact portion of the pedunculopontine tegmental nucleus, the central grey and intercollicular region, the ventral area of Tsai, the medial spiriform nucleus, the nucleus subrotundus, the anterior preoptic area, and the diagonal band of Broca. The parabrachial subnuclei have partially differential projections to these targets, some of which also receive projections from the nucleus of the solitary tract (Arends, Wild, and Zeigler:J. Comp. Neurol.278:405‐429, '88). Most of the targets, particularly those in the basal forebrain (viz., the periventricular nucleus and the strata cellulare internum and externum of the hypothalamus, the bed nucleus of the stria terminalis, and its lateral extension into the ventral paleostriatum, which may be comparable with the substantia innominata), have reciprocal connections with the parabrachial and solitary tract subnuclei and therefore may be said to compose parts of a “visceral forebrain system” analogous to that described in the rat (Van der Kooy et al:J. Comp. Neurol.224:1‐24, '84).The descending projections to the lower brainstem arise in large part from a ventrolateral subnucleus that may be comparable with the Kölliker Fuse nucleus of mammals. They are mainly to the ventrolateral medulla, nucleus ambiguus, and massively to the hypoglossal nucleus, particularly its tracheosyringeal portion. These projections are therefore likely to be importantly involved in the control of vocalization and respiration (Wild and Arends:Brain Res.407:191‐194, '87). Some of these results have been presented in abstract form (Wild, Arends, and Zeigler:Soc. Neurosci. Abst.

ISSN:0092-7317    

DOI:10.1002/cne.902930402

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe development of retinotopy in projections from the eye to the dorsal lateral geniculate (dLGN) and superior colliculus (SC) has been studied in the marsupial wallaby. Discrete retinal lesions were made and the remaining retinal projections were traced with horseradish peroxidase in animals at stages ranging from just after optic innervation of the dLGN and SC to the time when the projections are mature.Topographically organised projections could be recognized a few weeks after axons first reached the dLGN and SC with a topographically discrete projection from nasoventral retina recognized later than from dorsal, dorsotemporal, temporal, and temporoventral retina. Over time there was an increase in precision of the retinotopy as judged by an increase in sharpness of the borders of filling defects in the projection labelled with horseradish peroxidase. Refinement of the projection from temporal retina preceded that from nasal retina in both the dLGN and SC and in the former occurred concomitantly with the segregation of eye‐specific terminal bands. Refinement was complete 16 weeks after birth, prior to eye opening at around 20 weeks after birth. Inequalities in retinal representations in both nuclei were present from the time retinotopy could first be detected. This was before the inequalities in retinal ganglion cell distribution, which underly these representations in the adult, were obvious.Retinotopy and inequalities in retinal representation characteristic of the adult are present from a very early stage in the protracted development of visual projections in the wallaby. Refinement may involve death of inappropriately projecting cells, pruning of inappropriately projecting axon arborizations or could be achieved by growth of the retinorecipient neuropil. Temporonasal differences in the time course of refinement may reflect gradients of maturation in the retin

ISSN:0092-7317    

DOI:10.1002/cne.902930403

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe examined the subnuclear organization of projections to the parabrachial nucleus (PB) from the nucleus of the solitary tract (NTS), area postrema, and medullary reticular formation in the rat by using the anterograde and retrograde transport of wheat germ agglutinin‐horseradish peroxidase conjugate and anterograde tracing withPhaseolus vulgaris‐leucoagglutinin. Different functional regions of the NTS/area postrema complex and medullary reticular formation were found to innervate largely nonoverlapping zones in the PB.Thegeneral visceral part of the NTS, including the medial, parvicellular, intermediate, and commissural NTS subnuclei and the core of the area postrema, projects to restricted terminal zones in the inner portion of the external lateral PB, the central and dorsal lateral PB subnuclei, and the “waist” area. The dorsomedial NTS subnucleus and the rim of the area postrema specifically innervate the outer portion of the external lateral PB subnucleus. In addition, the medial NTS innervates the caudal lateral part of the external medial PB subnucleus.Therespiratory part of the NTS, comprising the ventrolateral, intermediate, and caudal commissural subnuclei, is reciprocally connected with the Kölliker‐Fuse nucleus, and with the far lateral parts of the dorsal and central lateral PB subnuclei. There is also a patchy projection to the caudal lateral part of the external medial PB subnucleus from the ventrolateral NTS.The rostral,gustatory part of the NTSprojects mainly to the caudal medial parts of the PB complex, including the “waist” area, as well as more rostrally to parts of the medial, external medial, ventral, and central lateral PB subnuclei.The connections of different portions of the medullary reticular formation with the PB complex reflect the same patterns of organization, but are reciprocal. Theperiambiguus regionis reciprocally connected with the same PB subnuclei as the ventrolateral NTS; therostral ventrolateral reticular nucleuswith the same PB subnuclei as both the ventrolateral (respiratory) and medial (general visceral) NTS; and theparvicellular reticular area, adjcent to the rostral NTS, and with parts of the central and ventral lateral and the medial PB subnuclei that also receive rostral (gustatory) NTS input. In addition, the rostral ventrolateral reticular nucleus and the parvicellular reticular formation have more extensive connections with parts of the rostal PB and the subjacent reticular formation that recieve little if any NTS input.The PB contains a series of topographically complex terminal domains reflecting the functional organization of its afferent sources in the NTS and medullary retic

ISSN:0092-7317    

DOI:10.1002/cne.902930404

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe parabrachial nucleus (PB) is the main relay for ascending visceral afferent information from the nucleus of the solitary tract (NTS) to the forebrain. We examined the chemical organization of solitary‐parabrachial afferents by using combined retrograde transport of fluorescent tracers and immunohistochemistry for galanin (GAL), cholecystokinin (CCK), and corticotropin‐releasing factor (CRF).Each peptide demonstrated a unique pattern of immunoreactive staining. GAL‐like immunoreactive (‐ir) fibers were most prominent in the “waist” area, the inner portion of external lateral PB, and the central and dorsal lateral PB subnuclei. Additional GAL‐ir innervation was seen in the medial and external medial PB subnuclei. GAL‐ir perikarya were observed mainly rostrally in the dorsal lateral, superior lateral, and extreme lateral PB.CCK‐ir fibers and terminals were most prominent in the outer portion of the external lateral PB; some weaker labeling was also present in the central lateral PB. CCK‐ir cell bodies were almost exclusively confined to the superior lateral PB and the “waist” area, although a few cells were seen in the Kölliker‐Fuse nucleus.The distribution of CRF‐ir terminal fibers in general resembled that of GAL, but showed considerably less terminal labeling in the lateral parts of the dorsal and central lateral PB, and the external medial and KöUlliker‐Fuse subnuclei. The CRF‐ir cells were most numerous in the dorsal lateral PB and the outer portion of the external lateral PB; rostrally, scattered CRF‐ir neurons were seen mainly in the central lateral PB.After injecting the fluorescent tracer Fast Blue into the PB, the distribution of double‐labeled neurons in the NTS was mapped. GAL‐ir cells were mainly located in the medial NTS subnucleus; 34% of GAL‐ir cells were double‐labeled ipsilaterally and 7% contralaterally. Conversely, 17% of the retrogradely labeled cells ipsilaterally and 16% contralaterally were GAL‐ir. CCK‐ir neurons were most numerous in the dorsomedial subnucleus of the NTS and the outer rim of the area postrema. Of the CCK‐ir cells, 68% in the ipsilateral and 10% in the contralateral NTS were double‐labeled, whereas 15% and 10%, respectively, of retrogradely labeled cells were CCK‐ir. In the area postrema, 36% of the CCK‐ir cells and 9% of the Fast Blue cells were double‐labelled CRF‐ir neurons were more widely distributed in the medial, dorsomedial, and ventrolateral NTS subnuclei, but double‐labeled cells were mainly seen in the medial NTS. Of CRF‐ir cells in the NTS, 26% ipsilaterally and 8%contralaterally were retrogradely labeled by the PB injections. Conversely, of retrogradely labeled cells in the NTS, 4% ipsilaterally and 6% contralaterally were CRF‐ir.Our results suggest that the functional specificity of NTS afferents may be maintained by their selective termination in particular PB subnuclei. In addition, the neuropeptides found in these pathways may provide chemical coding for the

ISSN:0092-7317    

DOI:10.1002/cne.902930405

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

年代:1990

数据来源: WILEY

摘要:

AbstractChandelier neurons are a unique subclass of cortical nonpyramidal neurons. The axons of these neurons terminate in distinctive vertically arrayed cartidges that synapse on the axon initial segment of pyramidal neurons. In this study, the rapid Golgi method and immunohistochemical techniques were used to characterize the morphology, regional distribution, laminar location, and biochemical content of chandelier neurons in the prefrontal and occipital cortices of three monkey species. As in our previous studies of visual areas V1 and V2 (Lund:Journal of Comparative Neurology 257:60‐92, 1987; Lund et al.:Journal of Comparative Neurology 202:19‐45, 1981, 276:1‐29, 1988), Golgi impregnations of areas 46 and 9 of macaque prefrontal cortex show chandelier neurons to be present in layers 2 through superficial 5. The vertical arrays of terminal boutons (axon cartridges) typical of this neuron class are also present in layers 2‐6 of the prefrontal cortex, but are not found in layer 1 or the subcortical white matter. In immunohistochemical studies, a calcium‐binding protein, parvalbumin, and a neuropeptide, corticotropin‐releasing factor (CRF), identify rod‐like structures that are morphologically similar to the axon cartridges of chandelier neurons seen in the Golgi material. In addition, both parvalbumin‐and CRF‐immunoreactive cartridges are located below the somata of unlabeled pyramidal neurons and appear to outline the axon initial segment of these neurons. However, we find that parvalbumin and CRF are present in only subpopulations of chandelier axon cartridges. For example, in adult primary visual cortex, parvalbumin‐labeled cartridges are present in very low numbers only in layers 2‐3, whereas in prefrontal and occipital association cortices these cartridges are a very prominent component of layers 2‐superficial 3 and are present in much lower density in the deeper cortical layers. In contrast to these findings in adult macaque monkeys, prefrontal and occipital association cortices of infant macaque monkeys contain a very high density of parvalbumin‐labeled cartridges in layer 4 and relatively few in the superficial cortical layers. Furthermore, in adult squirrel monkey prefrontal cortex, CRF‐labeled cartridges are predominately present in layer 4, but these CRF‐immunoreactive structures have not been observed in the homologous regions of infant or adult macaque monkeys. These findings indicate that even for neurons of such distinctive morphology and presumably constant functional role as chandelier neurons, factors such as regional and laminar location, age, and primate species are associated with differences in the biochemical content of su

ISSN:0092-7317    

DOI:10.1002/cne.902930406

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

年代:1990

数据来源: WILEY

摘要:

AbstractProjections of the locus coeruleus (LC) to the midbrain and hindbrain were analyzed by anterograde transport of the lectinPhaseolus vulgarisleucoagglutinin (PHA‐L). Following iontophoretic application of PHA‐L into the LC, the distribution of labeled axons was analyzed in sections processed for the immunoperoxidase method and in sections processed for double‐immuno‐fluorescence staining using antibodies to PHA‐L and to dopamine‐β‐hydroxylase. This combined staining approach proved to be necessary for the unequivocal identification of LC axons in the brainstem since all injections labeled many non‐noradrenergic axons whose distribution was different from that of LC fibers. The major new finding of the present study was the observation that large territories of the brainstem that receive a dense noradrenergic input are very sparsely innervated by the LC. Numerous labeled LC axons were observed in somatic afferent nuclei, tectum, pontine nuclei, interpeduncular nucleus, and inferior olivary complex. In contrast, very few labeled fibers were observed in autonomic and motor nuclei, and throughout the brainstem reticular formation, including raphe nuclei. Our data show that the distribution of LC axons in the brainstem is far less prominent than the projections of this nucleus to the forebrain and spinal cord. Our findings suggest that the dense NA projections to the core of the brainstem originate principally in non‐LC NA neurons. On the basis of the present anatomical findings, a prominent role of the LC in motor and integrative functions of the brainste

ISSN:0092-7317    

DOI:10.1002/cne.902930407

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe distribution and differential staining patterns of cytochrome oxidase (CO) activity in visual cortical areas have provided useful anatomical markers for the modular organization of area 17 (striate cortex) and area 18 in primates. In macaque and squirrel monkeys, previous studies have shown that the majority of cells that lie in areas of high CO activity are color selective, are nonoriented, and project to adjacent zones of high CO activity in area 17 and to stripes of high CO activity in area 18. By contrast, most cells in zones with weak CO activity in area 17 have relatively narrow orientation tuning and are not color selective (Livingstone and Hubel:J. Neurosci.4:309‐356, 2830‐2835, '84; 7:3371‐3377, '87). The periodic organization of CO activity in area 17, the „blobs,”︁ and the stripe‐like organization in area 18 thus seem to define visual cortical processing modules and/or channels in primates. We have investigated the organization of CO activity in areas 17 and 18 in two species of nocturnal prosimian primates[Galago crassicaudatus(GCC) andGalago senegalensis(GSS)] in order to evaluate CO staining patterns in primates that have been reported to possess almost exclusively rod retinae and no color vision.In area 17 of both species, our results show that, as in diurnal and nocturnal simian primates, the darkest CO staining occurs in layers III and IV, with clear periodicity in layer III (i.e., CO blobs) and homogeneous staining in layer IVβ, the cortical recipient sublayer of the geniculate parvocellular layers. In GCC, individual blobs in layer III appear to be larger and less frequent than has been reported for the macaque monkey. Unlike simian primates, both galago species exhibit clear CO periodicities within layer IVα, the cortical recipient sublayer of the magnocellular geniculate layers. In addition, faint CO periodicities are apparent in layer VI and scattered large darkly CO stained pyramidal cells are visible throughout layer V.Quantitative analysis suggests that CO periodicities are more frequent in GSS than in GCC, suggesting that there may be evolutionary pressure to maintain the same number of CO modules within the smaller striate cortex of the lesser galago, although this is not the trend found across distantly related species.CO activity in area 18 is less well‐developed than reported in other primates. In fact, we could not reliably identify discontinuities in CO staining in area 18 of GSS. Instead, where present, discontinuities in CO staining in area 18 of GCC appear as faint regularly spaced patches.Taken together, these results suggest underlying similarities in the basic features of primate cortical organization as revealed by CO staining. There are nonetheless some differences in the distribution of CO activity in visual cortex acros primate species. Thus, given species variation in visual niche requirements including differential dependence on color vision, it seems unlikely that CO blobs have evolved as a strictly color channe

ISSN:0092-7317    

DOI:10.1002/cne.902930408

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

年代:1990

数据来源: WILEY

摘要:

AbstractMammalian taste buds are distributed within several distinct subpopulations, innervated by branches of three cranial nerves. These taste bud populations originate and mature at different times in various mammalian species and are thought to play differential roles in the control of taste‐mediated behaviors. The hamster is a common animal for the electrophysiological study of the gustatory system, and it has been shown that taste buds innervated by the IXth nerve develop postnatally in this species. To delineate further the development of the gustatory system of hamsters, we quantified the number of taste buds appearing on the palatal, nasopharyngeal, and laryngeal epithelium from birth through 120 days of age. Taste buds are present in almost adult numbers on the soft palate at birth, but only 39% of these are mature. Distinct taste pores, indicative of mature taste buds, increase in number until about 20‐30 days of life, at which time all of the taste buds on the soft palate and on the nasoincisive papillae are fully developed. Taste buds are concentrated primarily on the posterior and medial portions of the soft palate. Taste buds located on the laryngeal surface of the epiglottis and the aryepiglottal folds are absent at birth and originate and mature over the following 120 days. Laryngeal taste buds are more concentrated on the aryepiglottal folds than on the epiglottis. On the soft palate and in the epiglottal region, the maturation of taste buds is well characterized by a logarithmic function (Y=a log X + B) relating the number of mature taste buds to postnatal age. On the soft palate, the length of the taste buds from base to apex correlates with the thickness of the epithelium, which increases with development. The diameter of mature taste buds on the soft palate does not change with age. In contrast to many mammalian species, in rodents taste bud development occurs mostly after birth. Rapid postnatal development progresses at a time when ingestive behavior is undergoing a number of significant changes. Taste buds in the larynx have been implicated in a number of laryngeal reflexes (i.e., apnea, swallowing) in several nonrodent species. The electrophysiological properties of superior laryngeal nerve fibers would suggest a similar function for epiglottal taste buds in the hams

ISSN:0092-7317    

DOI:10.1002/cne.902930409

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe centrifugal fibers innervating the goldfish retina were studied quantitatively by light and electron microscopy. These fibers originating from cell bodies in the olfactory bulb were labeled by antiserum to the tetrapeptide Phe‐Met‐Arg‐Phe‐NH2(FMRFamide). The number of FMRFamide‐immunoreactive (ir) centrifugal fibers in each eye of the adult goldfish (body length: 12‐15 cm) was 65 + 14 (mean ± S. D., n = 7). All of these fibers in the optic nerve and the retina were unmyelinated. Each FMRFamide‐ir centrifugal fiber runs along the optic fiber layer and gives several terminal arborizations in the outermost layer (layer 1) of the inner plexiform layer. Layer 1 is, therefore, densely covered by a plexus of terminal arborizations. Along these terminal arborizations, we found output synapses characterized by a cluster of small clear vesicles (40 nm in diameter) at the presynaptic site and a thickened membrane in the apposed retinal cell processes. In a sample area of 2,000 üm2, such synapses occurred at a density of one per 105 üm2, or about 13,000 per centrifugal fiber. Thus, the FMRFamide‐ir centrifugal fibers are likely to modulate retinal cell activity through an estimated total of 840,000 output s

ISSN:0092-7317    

DOI:10.1002/cne.902930410

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

年代:1990

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902930401

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

年代:1990

数据来源: WILEY