bluuebunny/crossref_metadata_2025 huggingface dataset:
Diencephalic gustatory connections in the channel catfish
Authors: Lamb Charles F. , Caprio John
Published: January 2005

Vertebrate gustatory systems include a tertiary ascending pathway from a secondary gustatory nucleus in the hindbrain to several forebrain nuclei. This connection is prominent in catfish, corresponding to their highly developed sense of taste. Iontophoretic injections of horseradish peroxidase were used to identify the specific target nuclei of the tertiary gustatory pathway in channel catfish and to characterize those nuclei by their respective connections.

Efferents from the secondary gustatory nucleus (nGS) ascend in the tertiary gustatory tract to the caudal inferior lobe, where they terminate caudally in the nucleus lobobulbaris (nLB) and nucleus centralis (nCLI), and rostrally in the nucleus diffusus (nDLI). Secondary projections from the facial lobe (FL) also terminate in the nLB and in the nucleus subglomerulus (nSG). The nLB forms three cell groups (caudal‐nLB, rostrolateral‐rl nLB, parvicellular‐nLBp), which project to the facial lobe, vagal lobe, and telencephalon, respectively. Cells from the nCLI project throughout the caudal inferior lobe and to the acousticolateral torus semicircularis and telencephalon, while the nDLI and nSG have intrinsic connections within the inferior lobe. The lateral thalamic nucleus projects from this region back to the nGS.

Through these identified connections several mechanisms for the processing of gustatory information can be proposed. The descending projections from the nLB and nLT could provide feedback to the primary and secondary gustatory nuclei, and could modulate feeding‐related motor circuits in the medulla. The connections of nCLI and nLBp with the telencephalon allow for the involvement of gustation in learning processes and other complex behaviors. © 1993 Wiley‐Liss, Inc.
Dendritic domains of medium spiny neurons in the primate striatum: Relationships to striosomal borders
Authors: Walker Ruth H. , Arbuthnott Gordon W. , Baughman Robert W. , Graybiel Ann M.
Published: January 2005

Medium spiny neurons are the projection neurons of the striatum. They receive the majority of striatal afferents, and they make up the vast majority of all neurons in the striatum. These densely spiny cells thus constitute a major substrate for input‐output processing in the striatum. In the experiments described here we analyzed the dendritic fields of spiny neurons in the squirrel monkey striatum and plotted their orientations with respect to the borders between striosomes and matrix. Medium‐sized spiny neurons in the caudate nucleus were filled intracellularly in a fixed‐slice preparation with the fluorescent dye Lucifer Yellow. Dendritic arbors were reconstructed following immunostaining of the injected neurons with antiserum to Lucifer Yellow and counterstaining for striosome/matrix compartments. A majority of the medium spiny neurons studied had dendritic arborizations that remained within their compartment of origin. Thus the striosome/matrix subdivision not only partitions neurotransmitter molecules and extrinsic striatal connections into two domains in the primate caudate nucleus, but also constrains the dendritic arbors of many projection neurons there. Other medium spiny neurons, however, in both striosomes and matrix, had dendrites that crossed from one compartment into the other. About a quarter of the spiny neurons reconstructed had at least one such crossing dendrite. These results suggest that compartmentalization of afferent and efferent processing by projection neurons in the primate striatum is not absolute. For a subpopulation of spiny neurons in striosomes and matrix, inputs to one compartment could have a direct influence on output cells of the other. © 1993 Wiley‐Liss,Inc.
Morphology of astrocytes and oligodendrocytes during development in the intact rat optic nerve
Authors: Butt Arthur M. , Ransom Bruce R.
Published: January 2005

The detailed three‐dimensional morphology of macroglial cells was determined throughout postnatal development in the intact rat optic nerve, a central nervous system white matter tract. Over 750 cells were analyzed by intracellular injection of horseradish peroxidase or Lucifer Yellow to provide a new perspective of glial differentiation in situ. Retrograde analysis of changes in glial morphology allowed us to identify developmental timetables for three morphological subclasses of astrocytes and oligodendrocytes, and to estimate their time of emergence from undifferentiated glial progenitors. Glial progenitors were recognised throughout postnatal development and persisted in 35‐day‐old nerves, where we suggest they represent adult progenitor cells. Astrocytes were present at birth, but the majority of these cells developed over the first week as three morphological classes emerged having either transverse, random, or longitudinal process orientation. Several lines of evidence led us to believe that the majority of astrocytes in the rat optic nerve were morphological variations of a single cell type. Young oligodendrocytes were first observed 2 days after birth, indicating that they diverged from progenitors at or near this time. During early development these cells extended a large number of fine processes, which then bifurcated and extended along axons. Later, as myelination proceeded, oligodendrocytes exhibited fewer processes which grew symmetrically and uniformly along the axons, resulting in a highly stereotypic mature oligodendrocyte form. Our analysis of oligodendrocyte growth suggests that these cells did not myelinate axons in a random manner and that axons may influence the myelinating processes of nearby oligodendrocytes. © 1993 Wiley‐Liss, Inc.
Dynorphin‐immunoreactive terminals in the rat nucleus accumbens: Cellular sites for modulation of target neurons and interactions with catecholamine afferents
Authors: van Bockstaele Elisabeth J. , Sesack Susan R. , Pickel Virginia M.
Published: January 2005

Dynorphin facilitates conditioned place aversion and reduces locomotor activity through mechanisms potentially involving direct activation of target neurons or release of catecholamines from afferents in the nucleus accumbens. We examined the ultrastructural substrates underlying these actions by combining immunoperoxidase labeling for dynorphin 1–8 and immunogold silver labeling for the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). The two markers were simultaneously visualized in single coronal sections through the rat nucleus accumbens. By light microscopy, dynorphin immunoreactivity was seen as patches of immunoreactive varicosities throughout all rostrocaudal levels of the nucleus accumbens. The dynorphin‐immunoreactive terminals identified by electron microscopy ranged from 0.2 to 1.5 μm in cross‐sectional diameter, contained numerous small (30–40 nm) clear vesicles, as well as one or more large (80–100 nm) dense core vesicles. From the dynorphin‐immunoreactive terminals quantitatively examined in single sections, 74% (173/370) showed symmetric synaptic junctions mainly with large unlabeled dendrites. Of the dynorphin‐immunoreactive terminals forming identifiable synapses, approximately 30% contacted more than one dendritic target. In addition, single dendrites frequently received convergent input from more than one dynorphin‐labeled terminal. Irrespective of their dendritic associations, dynorphin‐immunoreactive terminals also frequently showed close appositions with other axons and terminals; these included unlabeled (41%), TH‐labeled (10%) or dynorphin‐labeled axons (14%). In contrast to dynorphin‐immunoreactive terminals, TH‐labeled terminals formed primarily symmetric synapses with small dendrites and spines or lacked recognizable specializations in the plane of section analyzed. In some cases, single dendrites were postsynaptic to both dynorphin and TH‐immunoreactive terminals. We conclude that dynorphin‐immunoreactive terminals potently modulate, and most likely inhibit, target neurons in both subregions of the rat nucleus accumbens. This modulatory action could attenuate or potentiate incoming catecholamine signals on more distal dendrites of the accumbens neurons. The findings also suggest potential sites for presynaptic modulatory interactions involving dynorphin and catecholamine or other transmitters in apposed terminals.
Synaptic output of physiologically identified spiny stellate neurons in cat visual cortex
Authors: Anderson John C. , Douglas Rodney J. , Martin Kevan A. C. , Nelson J. Charmaine
Published: January 2005

Spiny stellate neurons of area 17 of the cat's visual cortex were physiologically characterised and injected intracellularly with horseradish peroxidase. Six neurons from sublamina 4A were selected. Five had the S‐type of simple receptive fields; one had a complex receptive field. Their axons formed boutons mainly in layers 3 and 4. An electron microscopic examination of 45 boutons showed that each bouton formed one asymmetric synapse on average. Spines were the most frequent synaptic target (74%); dendritic shafts formed the remainder (26%). On the basis of ultrastructural characteristics, 8% of the target dendrites were characterised as originating from smooth γ‐aminobutyrate‐ergic (GABAergic) neurons. Thus the major output of spiny stellate neurons is to other spiny neurons, probably pyramidal neurons in layer 3 and spiny stellates in layer 4.
Identification of the timing of S phase and the patterns of cell proliferation during hair cell regeneration in the chick cochlea
Authors: Stone Jennifer S. , Cotanche Douglas A.
Published: January 2005

Birds respond to hair cell loss by stimulating cell division in the otherwise mitotically quiescent sensory epithelium and by generating new hair cells. We examined cell proliferation during hair cell regeneration in chick basilar papilla by using 5‐bromo‐2′ ‐deoxyuridine (BrdU). Chicks were noise exposed for 4 or 24 hours and injected with BrdU, and cochleae were immunohistochemically labeled to detect BrdU. Immunoreactivity after short‐term postinjection survival identified when cells entered S phase. For both 4 and 24 hour exposures, cells in S phase were first detected in the sensory epithelium after an injection at 18 hours after the onset of exposure and were also present after injections at 24, 30, 36, 42, 48, 72, 96, 120, and 144 hours. The most cells in S (or G2) phase were detected at 42 and 72 hours for 24 hour exposures and at 48 hours for 4 hour exposures. Chicks that survived for long periods after injection had BrdU‐labeled hair cells indicating that precursor cells that divided in the presence of BrdU generated new hair cells. Moreover, labeled hair cells and supporting cells were grouped into discrete clusters, suggesting that cells within each cluster are clonally related. Support for this hypothesis was provided by experiments showing that the number of labeled cells increased when chicks survived for longer periods after a single BrdU injection. These findings suggest that progenitors within the sensory epithelium may undergo several rounds of division to generate the appropriate number of new hair cells and supporting cells.
Locustatachykinin immunoreactivity in the blowfly central nervous system and intestine
Authors: Lundquist C. Tomas , Clottens Frank L. , Holman G. Mark , Riehm John P. , Bonkale Willy , Nässel Dick R.
Published: January 2005

An antiserum raised against locustatachykinin I, one of four myotropic peptides that have been isolated from the locust brain and corpora cardiaca, was characterized by enzyme‐linked immunosorbent assay (ELISA) and used for immunocytochemical detection of neurons and endocrine cells in the nervous system and intestine of the blowfly Calliphora vomitoria. The ELISA characterization indicated that the antiserum recognizes the common C‐terminus sequence of the locustatachykinins I‐III. Hence, the cross reaction with locustatachykinin IV is less, and in competitive ELISAs no cross reaction was detected with a series of vertebrate tachykinins tested. It was also shown that the antiserum recognized material in extracts of blowfly heads, as measured in ELISA. In high‐performance liquid chromatography the extracted locustatachykinin‐like immunoreactive (Lom TK‐LI) material eluted in two different ranges. A fairly large number of LomTK‐LI neurons was detected in the blowfly brain and thoracicoabdominal ganglion. A total of about 160 LomTK‐LI neurons was seen in the proto‐, deuto‐, and tritocerebrum and subesophageal ganglion. Immunoreactive processes from these neurons could be traced in many neuropil regions of the brain: superior and dorsomedian protocerebrum, optic tubercle, fan‐shaped body and ventral bodies of the central complex, all the glomeruli of the antennal lobes, and tritocerebral and subesophageal neuropil. No immunoreactivity was seen in the mushroom bodies or the optic lobes. In the fused thoracicoabdominal ganglion, 46 LomTK‐LI neurons could be resolved. The less evolved larval nervous system was also investigated to obtain additional information on the morphology and projections of immunoreactive neurons. In neither the larval nor the adult nervous systems could we identify any efferent or afferent immunoreactive axons or neurosecretory cells. The widespread distribution of LomTK‐LI material in interneurons suggests an important role of the native peptide(s) as a neurotransmitter or neuromodulator within the central nervous system. Additionally a regulatory function in the intestine is indicated by the presence of immunoreactivity in endocrine cells of the midgut.
Tactile sensory input regulates basal and apomorphine‐induced immediate‐early gene expression in rat barrel cortex
Authors: Steiner Heinz , Gerfen Charles R.
Published: January 2005

Clipping of mystacial vibrissae on one side of the rat's snout result in sensorimotor asymmetries in normal behavior and in behavior induced by the dopamine receptor agonist, apomorphine. Immediate‐carly gene expression, a marker for short‐term changes in neuron function, was used to examine wheter this sensory deprivation leads to functional changes in the somatosensory barrel cortex under experimental conditions which reveal behavioral asymmetries. The expression of c‐fos and zif 268 immediate‐early genes was assessed with in situ hybridization histochemistry. Four hours after unilateral clipping of the mystacial vibrissae, the level of zif 268 mRNA was reduced in the corresponding part of the contralateral barrel field. Injection of apoorphine (5 mg/kg) resulted in increased expression of both c‐fos and zif 268 immediate‐early genes in cortex and striatum. This apomorphine‐induced increase was blocked in the sensory‐deprived somatosensory corted. Laminar analysis of gene regulation shwoed that vibrissae removal affected immediate‐early expression in all layers of the barrel cortex. These results demonstrate that: (1) basal zif 268 gene expression in neurons of the somatosensory cortex is dependent on sensory input, (2) cortical immediate‐early gene expression is increased after dopamine receptor activation, and (3) in the barrel cortex, this increase is also dependent on sensory input. We suggest that the observed reduction in gene expression after vibrissae removal reflects decreased activation of neurons in the barrel column by removal of sensory input. © 1994 Wiley‐Liss, Inc.
Pattern of striate cortical projections to the pretectal complex in the guinea pig
Authors: Lui F. , Giolli R. A. , Blanks R. H. , Tom E. M.
Published: January 2005

The primary goal of this study was a determine whether the striate cortex (Oc 1) of the guinea pig projects to the pretactal nucleus of the optic tract (NOT), the first postretinal station of the horizontal optokinetic pathway, and, if so, to analyze the anatomical organization of this cortico‐NOT projection. Other goals of this investigation are to identify other pretectal nuclear projections from the visual cortex in the guinea pig, and to determine whether there is any visuotopic organization in this pathway.

Axonal tracers (biocytin or 3H‐leucine) were injected into the striate cortex (Oc 1), and the tissue processed with histochemical or light autoradiographic techniques. All subcortical terminal labeling is ipsilateral in the basal ganglia and thalamic nuclei. Furthermore, projections are traced to the ipsilateral brainstem, including two areas of the pretectal complex: (1) one in the NOT, extending in some cases to the adjacent lateral portion of the posterior pretectal nucleus (PPN), and (2) one in the pars compacta of the anterior pretectal nucleus (APNc). The terminal fields in the APN are consistently located rostrally in the dorsolateral portion of the nucleus, independently of the injection site in Oc 1, whereas in the NOT the terminal fields shift slightly after injections placed in different locations in the striate cortex. A correlation of the injection sites in Oc 1 and terminal fields in the NOT reveals a loose topographic organization in the cortico‐NOT projection; accordingly, the rostrocaudal axis of the striate cortex projects to the lateromedial axis of the NOT, with a 90° rotation, whereas lateral parts of the striate cortex project diffusely throghout the rostrocaudal extent of the NOT.

These data show for the first that the NOT in the guinea pig receives a substantial projection form the visual cortex. Given the fact that in the guinea pig the optokinetic nystagmus shares some of the characteristics found in cat and monkey (i.e., consistent intial fast rise in the slow phase velocity and reduced asymmetry in monocular stimulation), the present findings lend support to the hypothesis that a cortical input to the NOT is a necessary condition for these oculomotor properties to be present. © 1994 Wiley‐Liss, Inc.
Neuronal nitric oxide synthase is localized in extrinsic nerves regulating perireceptor processes in the chemosensory nasal mucosae of rats and humans
Authors: Kulkarni Anjali P. , Getchell Thomas V. , Getchell Marilyn L.
Published: January 2005

Nitric oxide synthase is the enzyme responsible for the production of the free radical gas nitric oxide, which has been implicated as an intercellular messenger in both the central and peripheral nervous systems. Immunoreactivity for nitric oxide synthase is often coincident with the histochemical demonstration of NADPH‐diaphorase activity. Using an antibody to the neuronal form of nitric oxide synthase and a histochemical technique for NADPH‐diaphorase, we have compared the localization of immunoreactivity and histochemical reaction product in the nasal mucosae of rats and humans. Immunoreactivity for neuronal nitric oxide synthase was localized in the extrinsic perivascular innervation of the olfactory and vomeronasal mucosae of rats and in the olfactory mucosa of humans. In the rat nasal mucosa, specific groups of glands were also innervated; the density of nitrinergic innervation varied among them, with vomeronasal glands and posterior glands of the nasal septum being the most densely innervated. In contrast, NADPH‐diaphorase activity was present in olfactory, vomeronasal, and septal organ receptor neurons in rats and in olfactory receptor neurons in humans as well as in numerous nerve fibers, glands, and surface epithelial cells. The localization of neuronal nitric oxide synthase in extrinsic perivascular and periglandular nerve fibers suggests that nitric oxide may modulate the perireceptor processes of local blood flow and mucus secretion that influence the access to and clearance of chemical stimuli from rat and human chemosensory mucosae. © Wiley‐Liss, Inc.
Afferent and efferent connections of the habenula in the larval sea lamprey (Petromyzon marinus L.): An experimental study
Authors: Yañez Julián , Anadon Ramón
Published: January 2005

The habenula is an integrative center between the striatum and the limbic and motor systems. With the aim of achieving further understanding of the evolution of this structure in vertebrates, we carried out an experimental study of the afferent and efferent connections of the habenula of larval sea lamprey. Experimental procedures included in vivo and in vitro transport after injections of horseradish peroxidase (HRP) into the habenula, telencephalon, pineal organ, dorsal thalamus, and posterior tubercle as well as carbocyanine dye tracing (DiI). The combined results of these experiments showed that the pattern of habenular connections is very simple. Most afferents appear to originate from the lobus subhippocampalis and neighboring area, whereas the only efferents found coursed in the fasciculus retroflexus to the neuropil of the nucleus interpeduncularis. This neuropil comprises a commissural region in the rostral mesencephalon, two long bilateral areas extending in the basal mesencephalon and medulla oblongata to the trigeminal level, and, finally, a caudal commissural zone. The conspicuous habenular commissure contains interhemispheric fibers that appear to form occasional contacts within the habenulae. The lamprey habenula also receives a few immunocytochemically identified fibers (somatostatinergic, catecholaminergic, and serotoninergic fibers) from other sources. © 1994 Wiley‐Liss, Inc.
Differential glycosylation of auditory and vestibular hair bundle proteins revealed by peanut agglutinin
Authors: Goodyear Richard , Richardson Guy
Published: January 2005

Up to four morphologically distinct types of cross‐link are found between the stereocilia in the hair bundles of avian hair cells. These links are involved in mechanotransduction, force transmission across the bundle, and maintenance of hair bundle structure. They appear to be specialisations of the cell coat, but very little is known about their molecular composition. Chick inner ear tissues were therefore screened with a number of different lectins to find markers for specialisations of the hair bundle surface. One lectin, peanut agglutinin (PNA), which recognises the dissacharide Galβ1‐3GalNAc, was found to be a fairly selective marker for vestibular hair bundles, but it does not stain the stereocilia of auditory hair cells. The staining patterns observed with PNA in the vestibular system closely resemble those seen with a monoclonal antibody (mab) directed against a 275 kD component of the hair cell's apical surface known as the hair‐cell antigen (HCA). However, unlike PNA, the mab recognises both vestibular and auditory hair cells. A detailed comparison of the fluorescence staining patterns observed with PNA and the anti‐HCA mab indicates that binding sites for both ligands spatially codistribute on the surface of vestibular hair cells. The lectin and the anti‐HCA mab binding sites are both sensitive to trypsin treatment, and, with sections of the vestibular system, PNA pretreatment blocks subsequent anti‐HCA mab staining. Immunoelectron microscopy of vestibular hair bundles shows that PNA and the anti‐HCA mab both label a type of cross‐link known as the shaft connector. This link type is present on both auditory and vestibular hair bundles but reacts with PNA only in the vestibular system. The lectin jacalin, which has greater specificity for Galβ1‐3GalNAc than does PNA, also only labels vestibular and not auditory hair bundles. Although terminal sialic acid residues can block both PNA and jacalin binding, neuraminidase treatment does not unmask cryptic binding sites for these lectins on auditory hair cells but does reveal PNA and jacalin staining at a number of other locations in the inner ear. The results obtained with the lectins PNA and jacalin indicate that either the HCA or other components of the shaft links are differentially glycosylated in the vestibular and auditory epithelia of the bird. The functional significance for such a difference in glycosylation remains to be determined, but auditory and vestibular hair cells operate over different frequency ranges, and variations in glycosylation might confer different micromechanical properties on the hair bundles in these two systems. © 1994 Wiley‐Liss, Inc.
Postnatal development of voltage sensitive Na+ channels in rat brain
Authors: Xia Ying , Haddad Gabriel G.
Published: January 2005

Previous studies have shown that mammalian neuronal excitability increases with age, and this excitability may be related to development of Na+ channels. In addition, evidence suggests that Na+ channels are involved in the neuronal response to O2 deprivation. Because of this, we wished to examine the pharmacologic properties and neuroanatomical distribution of the Na+ channels in newborn brain and as a function of age. In this study, we used ligand‐binding techniques and autoradiography with 3H‐saxitoxin (STX) to investigate Na+‐channel distribution in brains of rats at postnatal days 0, 3, 10, 21, 35, and 120. We found that (1) in each area examined, the Scatchard plots for STX binding were linear in both immature and mature brains in a ligand concentration range of 0.4–64 nM; the slopes, however, were different between areas or ages, with Kd values ranging between 1 and 5 nM; (2) STX‐binding density was more than tenfold lower in the rostral brain and cerebellum at birth than in the adult and increased with age; (3) binding density in the newborn brainstem was higher than in other areas such as the cortex and cerebellum, which is opposite to the distribution in the adult; and (d) the brainstem had a different developing pattern with an early‐peak density level (P10–21) and a lower adult level. We conclude that (1) there is a major type of STX‐binding site in specific brain areas in the developing brain; (2) binding affinity is higher, but density lower, at birth than in the adult, especially in the rostral brain; and (3) developmental profiles of Na+ channels vary among brain areas with an early developmental time table in the brainstem and a later one in the cerebellum and rostral brain. © 1994 Wiley‐Liss, Inc.
Electrophysiological and morphological properties of light and dark cells isolated from mudpuppy taste buds
Authors: McPheeters Martha , Barber Andrew J. , Kinnamon Sue C. , Kinnamon John C.
Published: January 2005

Isolated Necturus taste receptor cells were studied by giga‐seal whole‐cell recording and electron microscopy to correlate electrophysiological properties with taste cell structural features. Dark (type I) cells were identified by the presence of dense granular packets in the supranuclear and apical regions of the cytoplasm. In response to a series of depolarizing voltage commands from a holding potential of −80 mV, these cells exhibited a transient, TTX‐sensitive inward Na+ current, a sustained outward K+ current, and a slowly inactivating inward Ca++ current. Light (type II) cells were identified by a lack of granular packets and by an abundance of smooth endoplasmic reticulum distributed throughout the cell. In addition, isolated light cells had clear vesicular inclusions in the cytoplasm and blebs on the plasma membrane. Light cells were divided into two functional populations based upon electrophysiological criteria: cells with inward and outward currents, and cells with outward currents only. Light cells with inward and outward currents had voltage‐activated Na+, K+, and Ca++ currents with properties similar to those of dark cells. In contrast, the second group of light cells had only voltageactivated outward K+ currents in response to depolarizing voltage commands. These data suggest that dark cells and light cells with inward and outward currents are capable of generating action potentials and releasing neurotransmitters onto gustatory afferent neurons in response to taste stimulation. In contrast, light cells with outward currents only likely serve a different function in the taste bud. © 1994 Wiley‐Liss, Inc.
Loss of dopamine D2 receptors varies along the rostrocaudal axis of the hippocampal complex in alzheimer's disease
Authors: Ryoo Han L. , Joyce Jeffrey N.
Published: January 2005

The anatomy of the hippocampus, including the organization of its intrinsic neural circuits and afferents, is organized along a rostrocaudal axis. Dopamine D2 receptors are expressed in specific regions of the hippocampal complex (hippocampal subfields, entorhinal cortex, perirhinal cortex) and show differential expression along this axis. The dentate gyrus and CA3/CA4 subfields show higher numbers of D2 receptors in the rostral than in the caudal levels. In contrast, the subiculum shows the reverse gradient. We report here that Alzheimer's disease (AD) is associated with reduced expression of the dopamine D2 receptor, but the effects differ with respect to the rostrocaudal axis and area within the hippocampal complex. The number of D2 receptors is significantly reduced in the molecular layer of the dentate gyrus, CA3 subfield, and subiculum. For the dentate gyrus and subiculum, there were greater losses at more rostral levels. The CA3/CA4 subfields showed the greatest losses caudally. The entorhinal cortex, which shows only modest expression of D2 receptors in controls, does not exhibit reduced numbers in AD. The external laminae of the rostral perirhinal cortex showed more significant losses than more caudally in this cortical field. The regions showing loss of D2 receptors do not typically contain neuritic plaques, neurofibrillary tangles, or significant neuron loss. Thus other mechanisms must account for the unique gradient of D2 receptor loss in the hippocampus. The regions of reduced expression of dopamine D2 receptors do correlate well with the terminal zone of the dentate association pathway, the afferents from the anlygdala and perirhinal cortex, and the sources of those afferents within the amygdala and perirhinal cortex. The specific patterns of reduced D2 receptor expression in AD are likely to contribute significantly to the disrupted information flow into and out of the hippocampus and, thus, of functions subserved by this system. © 1994 Wiley‐Liss, Inc.
Spatially and temporally differentiated patterns ofc‐fosexpression in brainstem catecholamilriergic cell groups induced by cardiovascular challenges in the rat
Authors: Chan R. K. W. , Sawchenko P. E.
Published: January 2005

Brainstem catecholaminergic neurons have been implicated as mediating adaptive autonomic and neuroendocrine responses to cardiovascular challenges. To clarify the nature of this involvement, immuno‐ and hybridization histochemical methods were used to followc‐fosexpression in these neurons in response to acute stimuli that differentially affect blood pressure and volume. From low basal levels, hypotensive hemorrhage (15%) provoked a progressive increase in the number and distribution of Fos‐immunoreactive (ir) nuclei in the nucleus of the solitary tract (NTS), the Al and C1 cell groups of the ventrolateral medulla, and in the pontine A5, locus coeruleus, and lateral parabrachial cell groups peaking at 2.0–2.5 hours after the challenge. Fos‐ir ventrolateral medullary neurons, subsets of which were identified as projecting to the paraventricular hypothalamic nucleus or spinal cord, were predominantly aminergic, whereas most of those in the NTS were not. Infusion of an angiotensin II antagonist blunted hemorrhage‐induced Fos expression in the area postrema, and attenuated that seen elsewhere in the medulla and pons. Nitroprusside‐induced isovolemic hypotension yielded a pattern of c‐fos induction similar to that seen following hemorrhage, except in the area postrema and the Al cell group, where the response was muted or lacking. Phenylephrineinduced hypertension stimulated a restricted pattern ofc‐fosexpression, largely limited to non‐aminergic neurons, whose distribution in the NTS conformed to the termination patterns of primary baroreceptor afferents, and in the ventrolateral medulla overlapped in part with those of vagal cardiomotor and depressor neurons. These findings underscore the importance of brainstem catecholaminergic neurons in effecting integrated homeostatic responses to cardiovascular challenges and their ability to responding strategically to specific modalities of cardiovascular information. They also foster testable predictions as to effector neuron populations that might be recruited to respond to perturbations in individual circulatory parameters. © 1994 Wiley‐Liss, Inc.
Microglia in the avian retina: Immunocytochemical demonstration in the adult quail
Authors: Navascués Julio , Moujahid Amale , Quesada Antonio , Cuadros Miguel A.
Published: January 2005

Immunocytochemical techniques were used in conjunction with the QH1 antibody to study the morphological characteristics and distribution of microglia in the avascular retina of an avian species (the quail). The majority of microglial cells appeared in the outer and inner plexiform layers throughout the entire retina, whereas a few microglial cells in the nerve fiber layer were seen only in the central zone of the retina, near the optic nerve head. In the outer plexiform layer, microglial cells were star‐shaped, with processes that ramified profusely in the horizontal plane. Fine process tips extended outward radially, insinuating themselves among the photoreceptors. A regular mosaic‐like arrangement of microglial cells was evident in the outer plexiform layer, with no overlapping between adjacent cell territories. Microglial cells in the inner plexiform layer ramified through the entire width of this layer, showing radial and horizontal processes. Microglia in the inner plexiform layer also tended to be regularly distributed in a mosaic‐like fashion, although there was slight overlapping between adjacent cell territories. Microglia density in this layer was approximately twice that in the outer plexiform layer. This pattern of microglial distribution was similar to that described in vascular retinae of several species of mammals a finding that suggests that blood vessels are not responsible for the final locations of microglia in the adult retina, and that microglial precursors must migrate through long distances before they reach their precise destination. © 1994 Wiley‐Liss, Inc.
Embryonic (PSA) N‐CAM reveals chains of migrationg neuroblasts between the lateral ventricle and the olfactory bulb of adult mice
Authors: Rousselot P. , Lois C. , Alvarez‐Buylla A.
Published: January 2005

In the brain of adult mice, cell division persists in the subventricular zone (SVZ) of the lateral ventricles. These SVZ cells migrate rostrally 3–5 mm to the olfactory bulb, where they differentiate into neurons. We have investigated the distribution of PSA‐N‐CAM in the adult mouse forebrain. Immunoreactivity for PSA‐N‐CAM precisely reveals the migratory pathway of SVZ cells. This pathway of PSA‐N‐CAM positive cells starts in the lateral wall of the lateral ventricle, where immunopositive cells form weblike patterns. The PSA‐N‐CAM positive pathway extends rostrally between the corpus callosum and the striatum into the anterior ventral telencephalon, and then into the core of the olfactory bulb. Experiments in which [3H]‐thymidine was injected systemically indicated that the majority of the dividing cells on the SVZ of the lateral ventricle and along the migratory pathway are positive to PSA‐N‐CAM or closly associated with PSA‐N‐CAM. Microinjection of [3H]‐thymidine into the SVZ of the lateral ventricle to label a small patch of dividing SVZ cells shows that neuroblasts that migrated away from the injection site are positive or are closely associated with other cells that are positive for PSA‐N‐CAM. Migrating cells are tethered together, forming long chains of immunopositive cells. The migratory pathway is formed by 30–40 of these immunopositive chains. Radially oriented individual PSA‐N‐CAM positive cells were observed in the olfactory bulb. These cells seem to have broken away from chains of immunopositive cells in the core of the olfactory bulb and to be migrating to more superficial layers. Little is known about the mechanisms of tangential migration during development and in adulthood. The cell‐cell arrangement revealed by PSA‐N‐CAM staining suggests new models for this form of neuronal migration. PSA‐N‐CAM staining suggests new models for this form of neuronal migration. PSA‐N‐CAM localization along the migratory pathway to the olfactory bulb suggests that in the adult brain this molecule plays a role in migration of neuronal precursors. © 1995 Willy‐Liss, Inc.
Dendritic reorganisation in the basal forebrain under degenerative conditions and its defects in Alzheimer's disease. II. Ageing, Korsakoff's disease, Parkinson's disease, and Alzheimer's disease
Authors: Arendt Thomas , Brückner Martina K. , Bigl Volker , Marcova Lena
Published: January 2005

Changes in the dendritic arborisation of Golgi‐impregnated basal forebrain neurones with respect to size, shape, orientation, and topology of branching were quantitatively investigated in ageing, Alzheimer's disease (AD), Korsakoff's disease (KD), and Parkinson's disease (PD). A reorganisation of the whole dendritic tree characterized by an increase in both the total dendritic length and the degree of dendritic arborisation as well as by changes in the shape of the dendritic field was found during ageing, in KD, PD, and AD. Dendritic growth under these conditions was related to the extent of cell loss in basal forebrain nuclei. There appeared to be major differences, however, with respect to the overall pattern of dendritic reorganisation between AD on one side and ageing, KD, and PD on the other side. In both ageing and KD, dendritic growth was largely restricted to the terminal dendritic segments, resulting in an increase of the size of the dendritic field (pattern of “extensive growth”). In AD, aberrant growth processes were frequently observed in the perisomatic area or on distal dendritic segments of basal forebrain neurones of the reticular type. Neurones with aberrant growth profiles were typically located in the direct vicinity of deposits of β/A4 amyloid. Perisomatic growth profiles were covered by the low‐affinity receptor of nerve growth factor p75NGFR. Aberrant growth processes were not present in ageing, KD, and PD. On the basis of the present study, it is concluded that under certain degenerative conditions, reticular basal forebrain neurones undergo a compensatory reorganisation of their dendritic arborisation, a process that has become defective in AD, thereby converting a physiological signal into a cascade of events contributing to the pathology of the disease. © 1995 Willy‐Liss, Inc.
Enhanced but delayed axonal sprouting of the commissural/associational pathway following a combined entorhinal cortex/fimbria fornix lesion
Authors: Schauwecker P. Elyse , McNeill Thomas H.
Published: January 2005

From previous lesion studies of the hippocampus it has been reported that axons of the commissural/associational pathway expand their termination zone in the molecular layer of the dentate gyrus by 20–25% in response to loss of input from the entorhinal cortex. However, although much is known about the response of the commissural/associational pathway with regard to extent, latency, and speed of the reinnervation response following an entorhinal cortex lesion, little is known about how the loss of additional afferent systems might modulate this response. To address this issue, we examined at 14, 30, and 45 days postlesion, the sprouting of commissural/associational afferents following either a unilateral fimbria fornix transection, a unilateral entorhinal cortex lesion, or combined lesions of both the entorhinal cortex and the fimbria fornix. Loss of septal innervation to the hippocampus was assessed using the cholinesterase stain, whereas sprouting from the commissural/associational pathway was determined from Holmes fiber‐stained sections. In addition, the Timms stain was used to examine the time course of the loss of terminal fields of the various zinc‐containing afferent systems within the hippocampus.

Following the removal of input to the hippocampus via the fimbria fornix transection, there was no evidence of sprouting of the commissural/associational fibers into the deafferented portion of the dentate gyrus. In contrast, rats receiving an entorhinal cortex lesion showed a significant increase (28%) in the width of the commissural/associational fiber plexus that was present by 14 days postlesion. By comparison, the magnitude of the expansion of the commissural/associational fiber plexus was significantly larger after lesioning both the entorhinal cortex and the fimbria than after the entorhinal cortex lesion alone (45% vs. 28%). In addition, the expansion of the commissural/associational fiber plexus that was not increased at 14 days postlesion but was significantly increased at 30 days postlesion. The delay in the sprouting of the commissural/associational pathway coincided with the time course of loss of zinccontaining fibers in the outer molecular layer of the dentate gyrus as assessed with the Timms stain. These results suggest that the magnitude and time course for the sprouting of axons from the commissural/associational pathway into the partially deafferented hippocampus of the adult rat is lesion dependent and that the effect of the loss of input from the entorhinal cortex can be modulated and enhanced by the concomitant depletion of input from the fimbria fornix. © 1995 Willy‐Liss, Inc.
The efferent projections of the periaqueductal gray in the rat: A Phaseolus vulgaris‐leucoagglutinin study. I. Ascending projections
Authors: Cameron Adrian A. , Khan Iqbal A. , Westlund Karin N. , Cliffer Kenneth D. , Willis William D.
Published: January 2005

This study has examined the ascending projections of the periaqueductal gray in the rat. Injections of Phaseolus vulgaris‐leucoagglutinin were placed in the dorsolateral or ventrolateral subregions, at rostral or caudal sites. From either region, fibers ascended via two bundles. The periventricular bundle ascended in the periaqueductal and periventricular gray matter. At the posterior commissure level, this bundle divided into a dorsal component that terminated in the intralaminar and midline thalamic nuclei, and a ventral component that supplied the hypothalamus. The ventral bundle formed in the deep mesencephalic reticular formation and supplied the ventral tegmental area, substantia nigra pars compacta, and the retrorubral field. The remaining fibers were incorporated into the medial forebrain bundle. These supplied the lateral hypothalamus and forebrain structures, including the preoptic area, the nuclei of the diagonal band, and the lateral division of the bed nucleus of the stria terminalis.

The dorsolateral subregion preferentially innervated the centrolateral and paraventricular thalamic nuclei and the anterior hypothalamic area. The ventrolateral subregion preferentially innervated the parafascicular and central medial thalamic nuclei, the lateral hypothalamic area, and the lateral division of the bed nucleus of the stria terminalis. Although the dorsolateral and ventrolateral subregions gave rise to differential projections, the projections from both the rostral and caudal parts of either subregion were similar. This suggests that the dorsolateral and ventrolateral subregions are organized into longitudinal columns that extend throughout the length of the periaqueductal gray. These columns may correspond to those demonstrated in recent physiological studies. © 1995 Willy‐Liss, Inc.
Structure and innervation of longitudinal and transverse abdominal muscles of the cricket, gryllus bimaculatus
Authors: Kawasaki Fumiko , Kita Hiroshi
Published: January 2005

Detailed morphological and physiological studies on the insect abdominal muscles, including their innervation and neuromuscular transmission, are essential for understanding their important role in respiratory movements. There are both longitudinal and transverse muscles in the ventral abdominal segments of the cricket, Gryllus bimaculatus. Muscle 202 was selected as an example of a longitudinal muscle. This muscle is, on average, 1.4 mm long, paired on both sides of the abdomen, and consists of 127 fibers whose mean maximum diameter is 32 μm; the average sarcomere length is 8.1 μm. It is innervated by two ipsilateral motoneurons in the second abdominal ganglion, the axons of which run in the ipsilateral first nerve root of the third abdominal ganglion. Two motor axons run in parallel from the two cell bodies and innervate in close proximity. Accordingly, large and small excitatory junctional potentials (EJPs) are recorded from the same fiber with slightly different thresholds when the first nerve root of the third abdominal ganglion is stimulated. Muscle 203, which is a transverse muscle that extends across the fifth abdominal sternum and is located over the fourth abdominal ganglion and muscle 202 on both sides, is, on average, 2.9 mm long and consists of 86 fibers with a maximum diameter of 33 μm. The average sarcomere length is 7.9 μm. The right or left half of the muscle is innervated mainly by a contralateral motoneuron in the third abdominal ganglion through the ipsilateral first nerve root of the third abdominal ganglion. Nerve branches of the first nerve root also reach muscles 188 and 218. Muscle 203 is additionally innervated by the first nerve roots of abdominal ganglia 1, 2, and 4. These innervations were ascertained both electrophysiologically and histologically. Individual muscle fibers of muscle 203 produced small EJPs in response to stimulation of the first nerve roots of abdominal ganglia 2, 3, and 4 and large EJPs in response to stimulation of the root from the first abdominal ganglion. The large and small EJPs in muscle 203 have properties similar to those in muscle 202. © 1995 Wiley‐Liss, Inc.
Corticostriatal connections of extrastriate visual areas in rhesus monkeys
Authors: Yeterian E. H. , Pandya D. N.
Published: January 2005

The striatal connections of extrastriate visual areas were examined by the autoradiographic technique in rhesus monkeys. The medial as well as the dorsolateral extrastriate regions project preferentially to dorsal and lateral portions of the head and of the body of the caudate nucleus, as well as to the caudodorsal sector of the putamen. The rostral portion of the annectant gyrus has connections to the caudal sector of the body and to the genu, whereas projections from the caudal portion of the lower bank of the superior temporal sulcus are directed to dorsal and central sectors of the head and the body, to the genu and the tail, as well as to the caudal putamen. The ventrolateral extrastriate region is related mainly to the ventral sector of the body, to the genu and the tail, and to the caudal putamen. In contrast, the striatal projections of the ventromedial extrastriate cortex resemble those of the medial and dorsolateral regions. The caudal inferotemporal cortex is related strongly to the tail of the caudate nucleus and to the ventral putamen.

The differential corticostriatal connectivity of the various extrastriate regions may contribute to the specific functional roles of these cortices. Thus, the connections from the dorsomedial, dorsolateral, and ventromedial areas to dorsal portions of the caudate nucleus and of the putamen may serve a visuospatial function. In contrast, the connections from the ventrolateral extrastriate and inferotemporal regions to the tail of the caudate nucleus and to the ventral putamen may have a role in visual object‐related processes. © 1995 Wiley‐Liss, Inc.