bluuebunny/crossref_metadata_2025 huggingface dataset:
An immunocytochemical study of the olfactory projections in the three‐spined stickleback, gasterosteus aculeatus, L
Authors: Honkanen Tapio , Ekström Peter
Published: January 2005

The distribution of olfactory fibers in the brain of the three‐spined stickleback was visualized by means of immunohistochemistry. The labeling of the olfactory fibers was produced by serum containing antibodies against somatostatin‐14. Olfactory fibers were observed entering the olfactory bulbs, where they terminated in the glomerular layer or collected into fascicles that coursed through the bulbs into the telencephalon without participating in the formation of the glomerules. In the telencephalon the fascicles, which belonged to the medial olfactory tract, formed two fiber systems: ventral descending fibers and dorsal descending fibers. The ventral descending fibers could be followed through the ventral telencephalon to the vicinity of the lateral tuberal nucleus. The dorsal descending fibers coursed via the anterior commissure to the posterior part of the telencephalon. Part of the postcommissural fibers of the dorsal descending system coursed to the posterior zone of the area dorsalis telencephali while others left the telencephalon via the medial forebrain bundle and could be followed to the periventricular hypothalamus. Some axons formed synaptic contacts with unlabeled cell bodies in the nucleus of the terminal nerve which, in this species, is situated immediately behind the bulbs. In addition, an extensive terminal field associated with the dorsal descending fibers was found in the ventromedial aspects of the telencephalon.

It is unlikely that the labeling represents immunoreactive somatostin‐14 because: 1) the labeling persisted after the absorption of the antiserum with synthetic somatostatin‐14; 2) antiserum against somatostatin‐14 from another manufacturer did not have this labeling property; and 3) the production of the absorbable labeling depended on the choice of fixative whereas the production of the unabsorbable labeling did not.
Electron microscopic analysis of S‐antigen‐ and serotonin‐immuoreactive neural and sensory elements in the photosensory pineal organ of the salmon
Authors: Ekström Peter , Meissl Hilmar
Published: January 2005

Photoreceptor cells in the pineal complex of poikilothermic vertebrates are regarded as homologous with the neuroendocrine pinealocytes in the mammalian pineal organ. They possess an indolamine metabolism, and they contain a number of substances that are immunochemically similar to phototransduction‐related proteins otherwise found in photoreceptors of the lateral eye retina. Using correlative light and electron microscopic pre‐embedding immunocytochemistry, we have identified photosensory and neural elements that are immunoreactive with specific antisera against serotonin (5‐hydroxytryptamine) and the 48 kDa soluble protein S‐antigen (arrestin). One type of serotonin‐immunoreactive (5HTir) photoreceptor cell was identified. This was characterized by a short basal pole, into which an immunoreactive (postsynaptic?) element protruded. Two types of ‐antigen‐immunoreactive (SAir) photoreceptor cells were observed, one characterized by a short basal pole, similar to that of the 5HTir photoreceptors and the other characterized by a long, extensively branching basal pole. In addition, two types of neurons bearing no morphological specializations typical of photoreceptor cells were SAir: bipolar neurons and multipolar neurons. These were often situated dorsally in the pineal organ. The results indicate an emergence of multiple lines of photoreceptor‐derived “pinealocytes” either early in phylogeny, or independently in different taxa. The results are discussed in relation to current theories of pineal evolution.
Connections between area 3b of the somatosensory cortex and subdivisions of the ventroposterior nuclear complex and the anterior pulvinar nucleus in squirrel monkeys
Authors: Cusick C. G. , Gould H. J.
Published: January 2005

The goal of this study was to determine whether somatosensory thalamic nuclei other than the ventroposterior nucleus proper VP have connections with area 3b of the postcentral cortex in squirrel monkeys. Small injections of the anatomical tracers wheat germ agglutinin conjugated to horseradish peroxidaseWGA‐HRP or H‐proline were placed in electrophysiologically identified representations of body parts. The results indicate that, besides the well‐established somatotopically organized connections with VP, area 3b has connections with three other nuclei of the somatosensory thalamus: the ventroposterior superior nucleus VPS [“shell” of VP], the ventroposterior inferior nucleus VPI, and the anterior pulvinar nucleus Pa. Injections confined to area 3b or involving adjacent parts of area 3a or area 1 indicate that connections between VPS, VPI, and Pa and the postcentral cortex are somatotopically organized. In VPS, connections related to the hand were found medially, and connections related to the foot were lateral. In VPI, connections with the cortical representations of the mouth, hand, and foot were successively more lateral. In Pa, connections related to the mouth, hand and foot were successively more ventral, lateral, and caudal, and the trunk region was caudomedial. The findings suggest that VPI contains a representation of all parts of the body, including the face. The connections of Pa with the primary somatosensory cortex, area 3b, the location of Pa relative to the ventroposterior nucleus, and the high degree of topographic order in the connections of Pa with the postcentral cortex suggest that Pa is an integral part of the somatosensory thalamus in monkeys and is homologous to the medial nucleus of the posterior group Pom in other mammals. Overall, the results contribute to the growing evidence that individual somatosensory cortical areas in monkeys receive inputs from multiple thalamic sources, and that a single thalamic nucleus has several cortical targets.
Catecholaminergic systems in the brain of a gymnotiform teleost fish: An immunohistochemical study
Authors: Sas Emilia , Maler Leonard , Tinner Barbro
Published: January 2005

The localization of catecholamines (CA) in the brain of Apteronotus leptorhynchus was studied with immunohistochemical techniques using antibodies to the enzymes tyrosine hydroxylase (TH), dopamine B‐hydroxylase (DBH), phenylethanolamine‐N‐methyltransferase (PNMT), and the neurotransmitter dopamine (DA). Telencephalic TH and DA immunoreactive (ir) neurons were located in the following structures: olfactory bulb, area ventralis telencephali partes ventralis, centralis, dorsalis, and intermediate. Diencephalic TH ir neurons were distributed in: nucleus preopticus periventricularis pars anterior, floor of preoptic recess, n. suprachiasmaticus, n. preopticus periventricularis pars posterior, n. anterior periventricularis, area ventralis lateralis, rostral region of posterior periventricular nucleus (paraventricular organ of other authors), periventricular nucleus of posterior tuberculum, n. recessus lateralis, n. tuberis lateralis pars anterior, and n. tuberis posterior.

Although most diencephalic TH ir structures were also DAir, the posterior periventricular nucleus, n. recessus lateralis pars medialis, n. recessus posterioris, and ventral region of nucleus lateralis tuberis pars anterior showed differences in the distribution of TH and DA immunoreactivity.

The rhombencephalic structures contained cell groups with different combinations of catecholamines as follows: TH and DBH ir neurons in the isthmic tegmentum (locus coeruleus); TH and DBH ir cells in the rostral medullary tegmentum ventral to VIIth nerve; TH and PNMT ir cells in the sensory nucleus of the vagus nerve; TH, DBH, and PNMT ir cells in the dorsal medullary tegmentum, TH and DBH ir cells in the dorsomedian postobecular region, ventral to the descending trigeminal tract and lateral to the central canal at medullospinal levels. This study shows that: (1) with few exceptions TH and DA ir coincides, (2) gymnotiforms possess similar DBH ir rhombencephalic groups, but additional telencephalic and rhombencephalic TH ir groups, and PNMT ir cells that were not reported previously in teleosts, and (3) the presence of CAergic fibers in the electrosensory system supports findings of their modulatory funtion in communication and aggression.
Disynaptic olfactory input to the hippocampus mediated by stellate cells in the entorhinal cortex
Authors: Schwerdtfeger Walter K. , Buhl Eberhard H. , Germroth Peter
Published: January 2005

Electrophysiological and anatomical studies indicate functional relationships between the olfactory bulb and the hippocampus, mediated by the lateral olfactory tract and perforant path. Fibres from the lateral olfactory bulb terminate in the molecular layer of the lateral entorhinal cortex, which contains stellate and pyramidal cells that project to the hippocampus. Therefore this study was performed to analyze whether a trineuronal, disynaptic chain connects the olfactory bulb and the hippocampus. In adult rats, Fast Blue was unilaterally injected into the septal hippocampus to label cells of origin of the entorhinohippocampal pathway. Lesions of the ipsilateral olfactory bulb induced anterograde terminal degeneration in the entorhinal cortex of the same animals. Fast Blue labelled, and thus hippocampally projecting entorhinal neurones in fixed vibratome slices of the operated brains were injected with Lucifer Yellow. Most of these neurones were stellate layer II and pyramidal layer III cells; in addition there were some sparsely spinous multipolar cells in layers II and III and sparsely spinous horizontal cells at the layer I/II border. Injected cells were photoconverted and processed for electron microscopy. Olfactory bulb lesions resulted in electron‐dense degeneration of abundant terminal boutons in the outer zone of entorhinal layer I. The relative frequency of degenerating boutons decreased towards deeper zones of the layer. In the outer zone, degenerated terminals predominantly contacted dendritic spines. These contacts could be seen on injected stellate cells but not on pyramidal cells. This study shows that the area dentata of the rat is reached by disynaptic afferent input from the olfactory bulb and thus is likely to process olfactory information. Oligosynaptic pathways might provide the hippocampus also with visual and auditory inputs; such fast transmitted polysensory information could be essential for the proposed participation of the hippocampus in attention‐related mechanisms.
Differential distribution of serotoninergic inputs on the goldfish mauthner cell
Authors: Gotow Takahiro , Triller Antoine , Korn Henri
Published: January 2005

The morphology and distribution of the serotoninergic 5‐HT input to the Mauthner cell M cell of a teleost, Carassius auratus, were analyzed at the light microscopic level. Immunohistochemical methods revealed that 1 most fibers innervating the M cell originate from the ventral and lateroventral regions of the rhombencephalon; 2 two groups of fibers contribute to this innervation, thick ones type I, 0.4–0.7 μm in diameter with terminal endings and thin ones type II, less than 0.2 μm that issue numerous beaded varicosities 4–10 μm from the target cell and only occasional side endings contacting it; 3 the density of immunoreactive profiles is uneven over the whole cell and predominates on the ventral dendrite; and 4 the two sets of axons, although overlapping, do not have the same distribution. Specifically, both classes are present on the ventral dendrite, whereas type II fibers are the only ones observed on the soma, in the region of the initial segment of the axon, and in the vicinity of the lateral dendrite. Functionally identified inputs on the M cell also have a regionalized distribution, depending, for example, on whether they belong to excitatory or inhibitory networks. Thus we propose that 5‐HT inputs have specific influences that are a function of their respective localization.
Synapsin I‐like immunoreactivity in nerve fibers associated with lingual taste buds of the rat
Authors: Finger Thomas E. , Womble Mary , Kinnamon John C. , Ueda Tetsufumi
Published: January 2005

Immunoreactivity to synapsin I, a neuronal phosphoprotein, was localized in free‐floating tissue sections prepared from lingual tissue of rats. Many nerve fibers within the tissue exhibited clear immunoreactivity including motor endplates on striated muscle, autonomic fibers innervating blood vessels or glands, and sensory fibers innervating muscles or the lingual epithelium including taste buds. Numerous immunoreactive fibers occurred within each taste bud, with fewer, fine fibers being dispersed in the epithelium between taste buds. The majority of the intragemmal immunoreactive fibers extended throughout the taste buds most of the distance outward from the basal lamina toward the surface of the epithelium. Fine, perigemmal fibers reached nearly to the epithelial surface. Ultrastructural analysis of the immunoreactive sensory fibers revealed that synapsin I‐immunoreactivity occurred diffusely throughout the cytoplasm, and heavily in association with microvesicles. The synaptic vesicles at the taste receptor cell‐to‐afferent fiber synapse were, however, not immunoreactive for synapsin I, although these vesicles fall into the size class shown to be immunoreactive in other systems. This absence of synapsin I may be a common property of vesicles in axonless short receptor cells.
Patterns of tachykinin expression and localization in developing feline neostriatum
Authors: Boylan M. K. , Levine M. S. , Buchwald N. A. , Fisher R. S.
Published: January 2005

The development of tachykinins in the neostriatum was determined qualitatively in order to characterize the ontogeny of an early‐forming neostriatal peptidergic system. Tachykinins were detected by immunohistochemistry in fetal, postnatal, and adult cats. Neostriatal cells and neurites expressed tachykinins as early as fetal age 30 and increased in frequency progressively with age. Initial tachykinin expression occurred in neostriatal neurons during their postmitotic migration. In the head of the caudate nucleus, clusters of tachykinin‐containing cells and fibers formed between fetal days 35 and 45, when the distribution of labeled neurons changed from a dispersed to an aggregated pattern. Between fetal days 45 and 50, tachykinin‐rich neuronal clusters increased in frequency and were distributed throughout the rostral caudate nucleus. In contrast to neurons in clusters, neurons in clusters, neurons in the complementary neuropil expressed tachykinins largely postnatally. Postnatal morphological maturation of tachykinins largely postnatally. Postnatal morphological maturation of tachykinin‐containing neurons paralleled the morphogenesis of medium spiny neostriatal cells. In addition, the caudate nucleus and putamen followed different spatiotemporal gradients of tachykinin expression. These results indicate that tachykinins are expressed in neostriatal neurons during the early ontogeny of the neostriatum and may function as trophic factors before synaptogenesis.
Regional distribution of binding sites for neuropeptide Y in cat and monkey visual cortex determined by in vitro receptor autoradiography
Authors: Rosier A. M. , Orban G. A. , Vandesande F.
Published: January 2005

The goal of this study was to elucidate the precise regional and laminar distribution of neuropeptide Y (NPY) binding sites in feline and primate visual cortex. By means of in vitro receptor autoradiography, NPY binding sites in primate and feline visual cortex were specifically labeled with 3HNPY. In cat area 17, the highest density of NPY‐binding sites was present in lamina I and the upper half of lamina II. The density then gradually decreased towards lamina VI. Areas 18 and 19 exhibited a similar binding site‐density profile. The decrease in density from superficial to deep layers was more gradual in area 18 than in areas 17 and 19. In monkey primary visual cortex (V1), layer IVc presented a high concentration of NPY binding sites, in addition to a dense zone of binding sites in layer I. Monkey secondary visual cortex (V2) displays a similar dense zone in layer I, but lacks such high density of NPY binding sites in layer IV. Therefore, the border between primary and secondary visual cortex coincides with the abrupt disappearance of this latter high density in layer IV. In cat as well as in monkey visual cortex, no significant differences were found between regions representing central vision and those representing the peripheral parts of the visual field. Comparison of our results for NPY binding sites with the distribution of alpha1‐adrenergic receptors, as recently described by Rakic et al. (J. Neurosci. 8(10):3670‐3690, 1988) for primate and Parkinson et al. (Brain Res. 457:70‐78, 1988) for feline visual cortex, revealed that those two patterns are very similar.
Projections of the parabrachial nucleus in the pigeon (Columba livia)
Authors: Martin Wild J. , Arends J. J. A. , Philip Zeigler H.
Published: January 2005

The 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. 13:308, '87).
Cluster organization and response characteristics of the giant fiber pathway of the blowfly Calliphora erythrocephala
Authors: Milde Jülgen J. , Strausfeld Nicholas J.
Published: January 2005

Intersegmental descending neurons (DNs) link the insect brain to the thoracic ganglia. Iontophoresis of cobalt or fluorescent dyes reveals DNs as uniquely identifiable elements, the dendrites of which are situated within a characteristic region of the lateral deutocerbrum. Here we demonstrate that DNs occur as discrete groups of elements termed DN clusters (DNCs). A DNC is a characteristic combination of neurons that arises from a multiglomerular complex in which the main components of each glomerulus are a characteristic ensemble of sensory afferents. Other neurons involved in the complex are local interneurons, heterolateral interneurons that connect DNCs on both sides of the brain, and neurons originating in higher centers of the brain. We describe the structure, relationships, and projections of eight DNs that contribute to a descending neuron cluster located ventrally in the lateral deutocerebrum, an area interposed between the ventral antennal lobes and the laterally disposed optic lobes. We have named this cluster the GDNC because its most prominent member is the giant descending neuron (GDN), which plays a cardinal role in the midleg “jump” response and which is implicated in the initiation of flight. The GDN and its companion neurons receive primary mechanosensory afferents from the antennae, terminals of wide‐ and small‐field retinotopic neurons originating in the lobula, and endings derived from sensory interneurons that originate in leg neuropil of the thoracic ganglia.

We demonstrate that DNs of this cluster share morphological and functional properties. They have similar axon trajectories into the thoracic ganglia, where they invade functionally related neuropils. Neurons of the GDNC respond to identical stimulus paradigms and share similar electrophysiological characteristics. Neither the GDN nor other members of its cluster show spontaneous activity. These neurons are reluctant to respond to unimodal stimuli, but respond to specific combinations of visual and mechanosensory stimulation. These results suggest that in flies groups of morphologically similar DNs responding to context‐specific environmental cues may cooperate in motor control.
Distribution and synaptic organization of dopaminergic axons in the lateral geniculate nucleus of the rat
Authors: Papadopoulos Georgios C. , Parnavelas John G.
Published: January 2005

In the present study, immunocytochemistry with an antiserum against dopamine (DA) revealed hitherto unknown terminal fields of DA axons in the lateral geniculate nucleus (LGN) of the rat. The innervation of all subdivisions of the LGN is achieved by a common set of afferent fibers that branch to form terminal fields of uneven density. The ventral lateral geniculate nucleus (LGv) receives slightly more DA axons than the dorsal lateral geniculate nucleus (LGd), whereas within the latter, DA afferents innervate the lateral part of the nucleus slightly more densely. Labeled axon terminals and varicosities, examined in single and serial ultrathin sections, were found in the extraglomerular neuropil in the LGd and in the neuropil of the LGv characterized by relatively simple synaptic relationships. They formed predominantly asymmetrical synaptic contacts with dendritic profiles. Occasionally, the postsynaptic elements were found to be presynaptic dendrites of presumptive interneurons. Some of the possible roles of this newly demonstrated DA afferent system in the physiology of the LGN and in the pathophysiology of diseases associated with impairment of dopaminergic activity are discussed.
Fine structure of the magnocellular subdivision of the ventral anterior thalamic nucleus (V Amc) of Macaca mulatta: II. Organization of nigrothalamic afferents as revealed with EM autoradiography
Authors: Kultas‐ilinsky K. , Ilinsky I. A.
Published: January 2005

An EM‐autoradiographic technique was used to identify the ultrastructural features and synaptic sites of nigral afferents to the ventral anterior nucleus pars magnocellularis (V Amc) of the rhesus monkey thalamus. The findings demonstrate that the nigral boutons are of medium‐sized to large, with the majority being of the en passant type. These boutons form symmetric synaptic contacts, and contain pleomorphic or entirely flat vesicles and numerous mitochondria. The nigral input is heavily biased towards thalamocortical projection neurons (PN), whose somata and dendrites represent about 82% of the postsynaptic sites of labeled boutons. The distal dendrites of local circuit neurons (LCN) comprise 13% of the postsynaptic sites. Nigral terminals appear to represent a single extrinsic afferent input to the somata and primary dendrites of thalamocortical projection neurons. A nigral input to LCN somata was not demonstrated but the possibility could not be excluded. Although the basic ultrastructural features of nigral boutons in the monkey are similar to those described earlier in the cat (Kultas‐Ilinsky et al.: J. Comp. Neurol. 216:390‐405,'83), essential species differences exist in the intensity of the nigral input and its distribution on thalamic neurons.
Intermediate and deep layers of the macaque superior colliculus: A golgi study
Authors: Ma Terence P. , Cheng Heng‐Wei , Czech Julie A , Rafols Jose A.
Published: January 2005

We studied the intermediate and deep laayers of the macaque superior colliculus by means of the Golgi technique in an attempt to better understand the structural features of this important oculomotor center. For this study, we examined the optic (stratum opticum, SO), intermediate gray (stratum griseum intermedium, SGI), intermediate white (stratunm album intermedium, SAI), and deep gray (stratum griseum profundum, SGP) layers. These are the four layers in which neurons having saccade‐related activity are localized. We identified eight neuronal types on the basis of differences in somatic and dendritic morphologies: large multipolar neurons (Type I); large pyramidal neurons (Type II); large fusiform neurons (Type III); medium fusiform neurons with spiny, radially. Oriented dendrites (Type IV); dedium round neurons with fan‐shaped dendritic trees (Type V); medium stellate neurons with varicose dendrites (Type VI); medium multipolar neurons with robust, spiny dendrites (Type VII); and local interneurons (Type VIII). Most neuronal, tyupes possessed features thakt are homologous to presynaptic dendritic features in other brain centers. With the exception of the kedium stellate neurons (Type VI), Which are aspinous, and the local interneurons (Type VIII), which are sparsely spinous, all other types had a moderate number of spines on their dendrites. Dendrites, that terminated in the optic layer had specializations not observed elsewhere, suggesting that these tips may sample a tectala afferent that is not present in the more ventral layers. These eight types comprise all the neuronala morphologies observed in a large number of Golgi‐impregnated macaque brains (n = 50). We suggest that they represent the full rage of neuron types in the saccade‐related layers of the macaque tectum.
Serotonin immunoreactive boutons form close appositions with respiratory neurons of the dorsal respiratory group in the cat
Authors: Voss M. D. , De Castro D. , Lipski J. , Pilowsky P. M. , Jiang C.
Published: January 2005

The aim of this study was to examine the location of serotonin immunoreactive boutons on both the soma and dendrites of neurons in the dorsal respiratory group by using a combination of intracellular recording and labelling and immunohistochemistry. Inspiratory neurons in the ventrolateral nucleus of the solitary tract (vl‐NTS) were intracellularly labelled with horseradish peroxidase (HRP) in anaesthetised adult cats. The morphology of 23 neurons, all antidromically activated from the contralateral C3 spinal segment, was examined. Six neurons displayed pronounced dendritic arborizations outside the vl‐NTS, with prominent dorsal and/or medial projections. The dendrites of the remaining neurons were almost entirely confined to the vl‐NTS. Intramedullary axon collaterals were detected in four of nineteen examined axons. Serotoninergic fibres were immunohistochemically demonstrated in the NTS, and the apposition of immunoreactive boutons to the HRP‐filled neurons examined at the light microscopic level. Boutons were identified in close apposition with the somata, proximal and distal dendrites of these neurons. However, the density of contacts was found to be substantially less than in a previous study of phrenic motoneurons (Lipski et al: Soc. Neurosci. Abst. 14:379, '88; Pilowsky et al: J. Neurosci. in press, '90). The relative paucity of contacts of serotonin immunoreactive boutons with premotor inspiratory neurons of the dorsal respiratory group indicates that the serotoninergic system affects respiratory pathways mainly at the level of respiratory motoneurons or at brainstem sites outside the vl‐NTS.
Brainstem afferents to the oculomotor omnipause neurons in monkey
Authors: Langer Thomas P. , Kaneko Chris R. S.
Published: January 2005

To determine how saccade‐related areas in the brainstem address the saccade generator, we examined the afferents to the nucleus raphe interpositus. This region contains the omnipause neurons, which are pivotal in the generation of saccades. Horseradish peroxidase injected iontophoretically into the nucleus raphe interpositus retrogradely labeled a variety of brainstem nuclei. The greatest numbers of labeled neurons were in the paramedian pontomedullary reticular formation, in the nuclei reticularis gigantocellularis, and paragigantocellularis lateralis. Labeling was more modest but consistent in the interstitial nucleus of Cajal and the adjacent mesencephalic reticular formation, the middle gray of the superior colliculi, the region dorsolateral to the nucleus reticularis tegmenti pontis, and the medial vestibular nucleus. A few neurons were labeled around the habenulopeduncular tract and in the medial portion of the nucleus of the fields of Forel, in the nucleus reticularis medullaris ventralis, and in the spinal nucleus of the trigeminal nerve, the cochlear nucleus, and the superior olivary complex.

The distribution and density of labeling suggest that omnipause neurons in the monkey are more intimately connected with other oculomotor structures than those in the cat. In addition, the rhombencephalic reticular afferents to the monkey omnipause neurons are more concentrated in their immediate vicinity than in the cat. The label consistently found dorsolateral to the nucleus reticularis tegmenti pontis may be a newly discovered link in saccade generation.
Calcium‐binding proteins, parvalbumin‐ and calbindin‐D 28k‐immunoreactive neurons in the rat spinal cord and dorsal root ganglia: A light and electron microscopic study
Authors: Antal Miklós , Freund Tamás F. , Polgár Erika
Published: January 2005

The distribution of two calcium‐binding proteins, parvalbumin (PV) and calbindin‐D 28K (CaBP), was studied by the peroxidase‐anti‐peroxidase immunohistochemical method at the light and electron microscopic level in the rat spinal cord and dorsal root ganglia. The possible coexistence of these two proteins was also investigated.

PV‐positive neurons were revealed in all layers of the spinal cord, except lamina I, which was devoid of labelling. Most of the PV‐positive cells were found in the inner layer of lamina II, lamina III, internal basilar nucleus, central gray region, and at the dorsomedial and ventromedial aspects of the lateral motor column in the ventral horn. Neuronal processes intensely stained for PV sharply delineated inner lamina II. With the electron microscope most of them appeared to be dendrites, but vesicle containing profiles were also found in a smaller number. CaBP‐positive neurons appeared to be dispersed all over the spinal gray matter. The great majority of them were found in laminae I, II, IV; the central gray region; the intermediolateral nucleus; and in the ventral horn just medial to the lateral motor column. Laminae I and II were densely packed with CaBP‐positive punctate profiles that proved to be dendrites and axons in the electron microscope. A portion of labelled neurons in lamina IV and on the ventromedial aspect of the lateral motor column in the ventral horn disclosed both PV‐ and CaBP‐immunoreactivity.

All of the funiculi of the spinal white matter contained a large number of fibres immunopositive for both PV and CaBP. The highest density of CaBP‐positive fibres was found in the dorsolateral funiculus, which was also densely packed with PV‐positive fibres. PV‐positive fibres were even more numerous in the dorsal part of the dorsal funiculus. The territory of the gracile funiculus in the brachial cord and that of the pyramidal tract in its whole extent were devoid of labelled fibres. In the thoracic cord, the dorsal nucleus of Clarke received a large number of PV‐positive fibres.

Dorsal root ganglia displayed both PV‐ and CaBP‐immunopositivity. The cell diameter distribution histogram of PV‐positive neurons disclosed two peaks‐‐one at 35 μm and the other at 50 μm. CaBP‐positive cells in the dorsal root ganglia corresponded to subgroups of small and large neurons with mean diameters of 25 μm and 45 μm, respectively.

On the basis of the location of perikarya and dendritic arborization patterns, PV‐ and CaBP‐positive cells are correlated with previously described and neurochemically or physiologically characterized neurons of the spinal cord and dorsal root ganglia.
Unbiased stereological estimation of the number of neurons in the human hippocampus
Authors: West Mark J. , Gundersen H. J. G.
Published: January 2005

The total numbers of neurons in five subdivisions of human hippocampi were estimated using unbiased Stereological principles and systematic sampling techniques. The method addresses the problems associated with the results and conclusions of previous quantitative studies, virtually all of which have been based on biased estimates of neuron densities. For each subdivision, the total number of neurons was calculated as the product of the estimate of the volume of the neuron‐containing layers and the estimate of the numerical density of neurons in the layers.

Each hippocampus was cut into 3‐mm‐thick slabs, transverse to the rostrocaudal axis. One 70‐μUm‐thick section from each slab was used in the analysis. The volumes of the layers containing neurons in five major subdivisions of the hippocampus (granule cell layer, hilus, CA3–2, CA1, and subiculum) were estimated with point‐counting techniques after delineation of the layers on each section. The numerical densities of neurons in each subdivision were estimated on the same sections with optical directors. The sampling used in both estimates was performed systematically in all three dimensions.

In an example of five hippocampi, the mean numbers of neurons (CV = SD/mean) in the different subdivisions were as follows: granule cells 15 × 106 (0.28), hilus 2.0 × 106 (0.16), CA3‐2 2.7 × 106 (0.22), CA1 16 × 106 (0.32), subiculum 4.5 × 106 (0.19). The stereological measurements contributed approximately 25% of the observed variance. Among the five subjects there was a significant inverse relationship between age (which ranged from 47 to 85 years) and the total number of neurons in CA1 (which ranged from 24 to 11 × 106).

An optimized sampling scheme for studies of the number of neurons in the human hippocampus has been designed on the basis of an analysis of variance of the estimates at different levels of the sampling scheme. Counting neurons in the five subdivisions of the human hippocampus with the optimized sampling scheme takes less than 4 hours.
Fluorescent histochemical localization of neutral endopeptidase‐24.11 (enkephalinase) in the rat brainstem
Authors: Back Stephen A. , Gorenstein Charles
Published: January 2005

Characterization of the distribution of the peptide‐degrading enzyme neutral endopeptidase‐24.11 (E.G. 3.4.24.11; NEP; enkephalinase) in the rat brainstem was examined by means of a unique fluorescent histochemical method. Enzyme staining was completely blocked by three potent NEP inhibitors (thiorphan, phosphoramidon, and JHF‐26) at a concentration of 50 nM, supporting the specificity of this method to visualize sites of NEP activity selectively.

At all levels of the brainstem, NEP was localized to cell bodies, cell processes, or terminal‐like fields and was localized to more than 90 distinct nuclei or subnuclei. In the mesencephalon these included the central gray, cuneiform n., dorsal and lateral tegmental n., inferior colliculus, interpeduncular n., lateral and medial geniculate n., central linear raphe n., mesencephalic n. of the trigeminal nerve, mammillary nuclei, Occulomotor n., red n., superior colliculus, ventral n. of the lateral lemniscus, substantia nigra‐ventral tegmental area, and the zona incerta.

In the pons, NEP staining was restricted to fewer regions or nuclei, including the dorsal and ventral cochlear n., facial n., motor trigeminal n., principal sensory trigeminal n., parabrachial nuclei, pontine n., the oral and caudal pontine reticular n., pontine olivary nuclei, several pontine tegmental nuclei, pontine raphe nuclei, and the trapezoid n. In the cerebellum, staining was localized largely to the granule cell layer of the cerebellar cortex. Scattered staining was observed in the molecular cell layer.

The medulla contained extensive NEP staining localized to nuclei that included the ambiguus n., dorsal motor n. of the vagus, hypoglossal n., inferior olivary n., prepositus hypoglossus n., solitary tract n., nuclei of the spinal tract of the trigeminal n., and the lateral, medial, and superior vestibular nuclei. Nuclei of the medullary reticular formation that were also richly stained for NEP included the raphe magnus n., raphe obscurus n., raphe pallidus n., dorsal, lateral, and ventral reticular nuclei of the medulla, and the gigantocellular, lateral paragigantocellular, linear, paramedian and parvicellular reticular nuclei.

The widespread distribution of NEP in the brainstem suggests the existence of a number of functional systems, including the pathways involved in the mechanisms of pain and analgesia, which are potential targets of NEP inhibitors. In most regions, the distribution of NEP closely overlapped with that reported for the enkephalins, and showed a more restricted overlap with the reported distribution of substance P.
Denervation‐induced intraspinal synaptogenesis of calcitonin gene‐related peptide containing primary afferent terminals
Authors: McNeill D. L. , Carlton S. M. , Coggeshall R. E. , Hulsebosch C. E.
Published: January 2005

The purpose of the present study is to provide evidence that chronic spinal denervation leads to an increase in numbers of synaptic terminals from a specific population of primary afferent fibers. Rats were unilaterally deafferented for 35 days (chronic denervation) by dorsal rhizotomies performed from T2 to T8 and T10 to L5, which isolates or spares the T9 root. The contralateral T9 root was spared by similar surgery 5 days (acute denervation) prior to sacrifice. The survival time on the chronic side presumably allows sprouting of T9 primary afferents to occur, whereas the time on the acute side does not. The terminals were labeled with calcitonin gene‐related peptide (CGRP), which is a compound that labels a specific population of primary afferent fibers and terminals, and stereological methods were used to determine the numbers of immunolabeled terminals in laminae I and IIo on the chronic and acute sides of the T9 spinal cord. The findings are that the chronic side had approximately twice as many terminals as the acute side. This difference is statistically significant. These findings are compatible with the hypothesis that chronic denervation leads to synaptogenesis from surviving primary afferent fibers.
Early climbing fiber interactions with Purkinje cells in the postnatal mouse cerebellum
Authors: Mason Carol A. , Christakos Sylvia , Catalano Susan M.
Published: January 2005

The time and place of initial contacts between afferent axons and their target cells are not known for most regions of the mammalian CNS. To address this issue, we have selectively visualized afferent climbing fiber axons together with their synaptic targets, Purkinje cells, in postnatal mouse cerebellum. Climbing fibers were orthogradely labeled by injection of rhodamine isothiocyanate into their brainstem source, the inferior olivary nucleus. Purkinje cells were localized with an antibody to a calcium‐binding protein, calbindin D‐28k(CaBP), in the same section or in adjacent sections.

A novel view of the olivocerebellar projection and the morphology of climbing fiber arbors prior to the well‐known “nest” stage has emerged from this analysis. At birth, climbing fibers project into the zone of Purkinje cells, before these cells have aligned into a monolayer. During this phase, climbing fibers have simple morphologies consisting of relatively unbranched terminal arbors and small tapered growing tips. Purkinje cells are arranged 3–6 cells deep and have tufted dendrites and relatively smooth somata.

By postnatal days 3–4, climbing fibers branch over several adjacent Purkinje cell perikarya, which are still organized in a band several cells thick. From postnatal days 5–7, when climbing fibers subsequently make focused nests on individual cells, Purkinje somata are smoother and form a more distinct monolayer. Up to this time, however, climbing fibers continue to associate with Purkinje perikarya, even though Purkinje cell dendrites have emerged and branched extensively. By postnatal days 8–10, climbing fiber terminals climb onto the trunk of the relatively mature Purkinje dendritic tree.

At birth, mossy fibers originating from the pontine nuclei resemble immature climbing fibers in that they also have a simple unbranched morphology and growing tips, but project only so far as the internal granule cell layer. Occasional individual fibers reach into the Purkinje zone both at postnatal day 0 and postnatal day 4, confirming that the fibers formerly described as “combination fibers” (Mason and Gregory, '84, J. Neurosci. 4:1715–1735) can be mossy in origin.

These data demonstrate that climbing fibers project among Purkinje cells earlier than suspected, before these afferents begin to arborize and form pericellular nests. Our observations are not in accord with the view derived from autoradiographic tracing studies that, as in other cortical areas, climbing afferents wait in the vicinity of Purkinje cells in the early neonatal period, then advance onto these cells in synchrony with Purkinje cell alignment into a monolayer and dendritic maturation. Instead, climbing afferents associate with Purkinje perikarya for an extended period during target cell positioning and initial dendritic growth, lagging behind in their translocation up relatively mature Purkinje dendrites.
Amygdalonigral pathway: An anterograde study in the rat with Phaseolus vulgaris leucoagglutinin (PHA‐L)
Authors: Conzales Cathleen , Chesselet Marie‐Francoise
Published: January 2005

The projection from the central nucleus of the amygdala to the substantia nigra was labeled by injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin into different subregions of the nucleus. A sparse projection of labeled bouton‐like swellings was observed in the rostral, medial substantia nigra pars compacta and ventral tegmental area from all subregions of the central nucleus of the amygdala that were injected. A dense projection of labeled axons and bouton‐like swellings was observed in the lateral part of the substantia nigra pars compacta and pars lateralis when the injection site included the dorsal and rostral central nucleus. Heavy labeling was also seen in the lateral retrorubral field in these cases. In no instances were labeled terminals observed in the substantia nigra pars reticulata. The same pattern of labeling in the lateral substantia nigra and retrorubral field was seen after injections rostral to the central nucleus or dorsal and medial to it in the sublenticular region. The results suggest that the amygdalonigral pathway contributes to the innervation of extensive areas of the substantia nigra pars compacta. The major component of the pathway, however, projects only to a subregion of the substantia nigra. The origin of this pathway is confined to a discrete region of the dorsal central nucleus of the amygdala but extends rostrally into an area that is part of the “extended amygdala.”
Cytochrome oxidase response to cochlea removal in chicken auditory brainstem neurons
Authors: Hyde Gregory E. , Durham Dianne
Published: January 2005

Changes in cytochrome oxidase (CO) activity were studied in the chick brainstem auditory nuclei, n. magnocellularis (NM) and n. laminaris (NL), following unilateral cochlea removal. Chickens aged 10 days or 56 weeks underwent unilateral cochlea removal. Following survival periods of 30 minutes to 14 days for the 10‐day‐old birds and 6 hours or 14 days for the 56‐week‐old birds, the animals were perfused with paraformaldehyde/glutaraldehyde fixative. Cryostat sections of the brainstem were then prepared for CO histochemistry. Microdensitometry was used to quantify the difference in CO staining in NM and NL ipsilateral and contralateral to the cochlea removal. Since the cochlea projects to the ipsilateral NM, the contralateral NM was used as a within‐animal control.

In normal chickens, NM cell bodies and the cell bodies and dendrites of NL neurons stain darkly for CO in both young and adult birds. In 10‐day‐old birds, there is no significant change in CO staining in NM from 30 minutes to 3 hours after cochlea removal. Then, a rapid biphasic change in CO staining was found in the ipsilateral NM. An increase in staining was observed 6 to 24 hours postoperatively, followed by a decrease in CO staining at 3‐ to 14‐day survival times. In the 56‐week‐old birds, no increases in CO staining were observed 6 hours after cochlea removal, but a decrease in CO staining was found 14 days postoperatively. In NL, no changes were observed until 3 days (10‐day‐old birds) or 14 days (56‐week‐old birds) after cochlea removal. Then a decrease in CO staining was observed in the dendritic and glial/fiber regions of NL containing axons from the deafferented NM.

Thus it appears that afferent input has a regulatory effect on the oxidative metabolism of neurons in the chicken auditory brainstem nuclei, an effect that differs with the age of the animal at the time of afferent manipulation.
Structural homology of identified motoneurones in larval and adult stages of hemi‐ and holometabolous insects
Authors: Breidbach Olaf , Kutsch Wolfram
Published: January 2005

The set of neurones innervating the dorsal longitudinal muscles was studied with cobalt and nickel backfills in: (1) larval and adult locusts (Schistocerca gregaria and Locusta migratoria), (2) the larval and adult beetle (Zophobas morio), and (3) various segments of these insect species. In all specimens 11 neurones were encountered, which can be subdivided into a group of 7 motoneurones that stem from the next anterior ganglion and 4 neurones located in the ganglion of the segment containing the muscles. The latter group comprises 2 contralateral and 2 medial somata, of which one is a dorsal unpaired median neurone. The results were analysed under different aspects. This neural set and the basic structure of the dendritic fields is similar in: (1) different segments (serial homology), (2) the larval stage and imago of the same species with or without a pronounced metamorphosis (ontogeny), and (3) the studied hemi‐ and holometabolous insects (phylogeny). Our results support the notion that the structure of these neurones is conserved irrespectively of changes in the periphery and strategy of postembryonic development.