bluuebunny/crossref_metadata_2025 huggingface dataset:
Interconnections between the primate cerebellum and midbrain near‐response regions
Authors: May Paul J. , Porter John D. , Gamlin Paul D. R.
Published: January 2005

The goal of this study was to determine the pattern of the connections between the midbrain and cerebellum that may play a role in the modulation of the near‐response in the macaque. Injection of the retrograde tracer wheat germ agglutinin conjugated horseradish peroxidase (WGA‐HRP) into the physiologically identified midbrain near‐response region, which includes the supraoculomotor area, labelled cells throughout the deep cerebellar nuclei. However, labelled cells were particularly concentrated in the ventrolateral corner of the contralateral posterior interposed nucleus and in the contralateral and, to a lesser extent, the ipsilateral fastigial nuclei. Subsequently, injections of WGA‐HRP were used to define the midbrain terminations of the deep cerebellar nuclei. Fastigial nucleus injections labelled terminals in a band along the border between the oculomotor nucleus and the supraoculomotor area that included the Edinger‐Westphal nucleus. Injections of the posterior interposed nucleus labelled terminals in the portion of the supraoculomotor area dorsal to the fastigial projection and did not involve the Edinger‐Westphal nucleus. In both cases, the terminal label was primarily found contralaterally. In contrast, retrogradely labelled cells were primarily found ipsilaterally within the supraoculomotor area following cerebellar injections. Retrogradely labelled cells projecting to the deep nuclei were also found bilaterally in the anteromedian nucleus, along with sparse terminal label.

Taken as a whole, these results demonstrate the presence of a highly specific pattern of labelling in the supraoculomotor area, which may indicate that the posterior interposed nucleus and the fastigial nucleus play different roles in the control of the near‐response. Alternatively, these projections may subserve other functions, such as modulating the pupillary light reflex. The fact that the projection from the deep nuclei is primarily contralateral, while the supraoculomotor projection to the deep nuclei is primarily ipsilateral, suggests that this may not be a simple feedback system, but may instead be involved in balancing the gains in the two eyes. In sum, physiological experiments have indicated the presence of near‐response neurons in the midbrain supraoculomotor area and have indicated that the cerebellum may play a role in modulating the components of the near‐response, as well as activity in the intrinsic eye muscles. The present experiments suggest a pattern of connections that might subserve this cerebellar modulation.
Response of retinal terminals to loss of postsynaptic target neurons in the dorsal lateral geniculate nucleus of the adult cat
Authors: Pearson Helen E. , Stoffler Deborah J. , Sonstein William J.
Published: January 2005

We have used the neurotoxin kainic acid to produce rapid degeneration of neurons in the dorsal lateral geniculate nucleus (dLGN) of the adult cat. This degeneration mimics the rapid loss of geniculate neurons seen after visual cortex ablation in the neonate. Subsequent anterograde transport of horseradish peroxidase injected into the eye was used to reveal the projection patterns of retinal ganglion cell axons at different survival periods after the kainic acid injection. The density of retinal projections to the degenerated regions of the geniculate was reduced considerably at 4 and 6 months survival, but at 2 months was not significantly different from normal. The laminar pattern of projections to degenerated regions of the geniculate did not change in any animals studied, even when an adjacent lamina contained surviving cells. Electron microscopic examination of degenerated dLGN revealed intact retinal (RLP) and RSD terminals at all survival times, although the density of terminals appeared much reduced when compared to controls. Some RLP terminals exhibited the “dark reaction” of degeneration and these degenerating terminals were most numerous at 2 months survival. These findings demonstrate that, in response to degeneration of their usual target cells, mature retinal ganglion cells will withdraw their axon terminals from these regions of degeneration. We conclude that mature retinal ganglion cells continue to be dependent on target integrity for the maintenance of a normal axonal arborization.
Immunocytochemical localization of luteinizing hormone‐releasing hormone (LHRH) in the nervus terminalis and brain of the big brown bat, Eptesicus fuscus
Authors: Oelschläger Helmut A. , Northcutt R. Glenn
Published: January 2005

Little is known about the immunohistochemistry of the nervous system in bats. This is particularly true of the nervus terminalis, which exerts strong influence on the reproductive system during ontogeny and in the adult.

Luteinizing hormone‐releasing hormone (LHRH) was visualized immunocytochemically in the nervus terminalis and brain of juvenile and adult big brown bats (Eptesicus fuscus). The peripheral LHRH‐immunoreactive (ir) cells and fibers (nervus terminalis) are dispersed along the basal surface of the forebrain from the olfactory bulbs to the prepiriform cortex and the interpeduncular fossa. A concentration of peripheral LHRH‐ir perikarya and fibers was found at the caudalmost part of the olfactory bulbs, near the medioventral forebrain sulcus; obviously these cells mediate between the bulbs and the remaining forebrain. Within the central nervous system (CNS), LHRH‐ir perikarya and fibers were distributed throughout the olfactory tubercle, diagonal band, preoptic area, suprachiasmatic and supraoptic nuclei, the bed nuclei of stria terminalis and stria medullaris, the anterior lateral and posterior hypothalamus, and the tuber cinereum. The highest concentration of cells was found within the arcuate nucleus. Fibers were most concentrated within the median eminence, infundibular stalk, and the medial habenula.

The data obtained suggest that this distribution of LHRH immunoreactivity may be characteristic for microchiropteran (insectivorous) bats. The strong projections of LHRH‐containing nuclei in the basal forebrain (including the arcuate nucleus) to the habenula, may indicate close functional contact between these brain areas via feedback loops, which could be important for the processing of thermal and other environmental stimuli correlated with hibernation.
Organization of association projections from area 17 to areas 18 and 19 and to suprasylvian areas in the cat's visual cortex
Authors: Ferrer José Manuel R. , Kato Nobuo , Price David J.
Published: January 2005

Cells in area 17 that are labelled by single, discrete injections of retrogradely transported tracers into extrastriate visual areas are discontinuously distributed in dense patches. In this study we made multiple, closely spaced injections of fluorescent dyes into extrastriate areas, to generate large deposits that would reveal whether the distributions of corticocortical cell bodies in area 17 are truly patchy or appear clustered only after small injections. By injecting a different tracer into each extrastriate area, or group of areas, we examined the spatial relationships between the populations of association cells.

All deposits of tracers in areas 18, 19, or suprasylvian cortex, irrespective of size, label cells in a series of clusters in topographically related parts of area 17. We conclude that the complete populations of cells in area 17 that project to areas 18, 19, and the lateral suprasylvian cortex are all genuinely distributed in a patchy fashion. There appears to be a complex relationship between the sets of association cells projecting to different extrastriate regions: they do not completely overlap, only partially, and share some cortical zones but not others.

In these experiments, only tiny percentages (2–5%) of labelled cells in the overlapping regions were filled with both tracers, suggesting that very few association cells in area 17 project to more than one of the extrastriate areas we studied.

By comparing the dimensions of each injection site and of the labelled region in area 17, we estimated the extent of the convergence from area 17 to areas 18, 19, and posteromedial suprasylvian areas in retinotopic terms. The functional convergence was very similar in these pathways.
Five topographically organized fields in the somatosensory cortex of the flying fox: Microelectrode maps, myeloarchitecture, and cortical modules
Authors: Krubitzer Leah A. , Calford Mike B.
Published: January 2005

Five somatosensory fields were defined in the grey‐headed flying fox by using microelectrode mapping procedures. These fields are: the primary somatosensory area, SI or area 3b; a field caudal to area 3b, area 1/2; the second somatosensory area, SII; the parietal ventral area, PV; and the ventral somatosensory area, VS. A large number of closely spaced electrode penetrations recording multiunit activity revealed that each of these fields had a complete somatotopic representation. Microelectrode maps of somatosensory fields were related to architecture in cortex that had been flattened, cut parallel to the cortical surface, and stained for myelin. Receptive field size and some neural properties of individual fields were directly compared. Area 3b was the largest field identified and its topography was similar to that described in many other mammals. Neurons in 3b were highly responsive to cutaneous stimulation of peripheral body parts and had relatively small receptive fields. The myeloarchitecture revealed patches of dense myelination surrounded by thin zones of lightly myelinated cortex. Microelectrode recordings showed that myelin‐dense and sparse zones in 3b were related to neurons that responded consistently or habituated to repetitive stimulation respectively. In cortex caudal to 3b, and protruding into 3b, a complete representation of the body surface adjacent to much of the caudal boundary of 3b was defined. Neurons in this area habituated rapidly to repetitive stimulation. We termed this caudal field area 1/2 because it had properties of both area 1 and area 2 of primates.

In cortex caudolateral to 3b and lateral to area 1/2 (cortex traditionally defined as SII) we describe three separate representations of the body surface coextensive with distinct myeloarchitectonic appearances. The second somatosensory area, SII, shared a congruent border with 3b at the representation of the nose. In SII, the overall orientation of the body representation was erect. The lips were represented rostrolaterally, the digits were represented laterally, and the toes were caudolateral to the digits. The trunk was represented caudally and the head was represented medially. A second complete representation, PV, had an inverted body representation with respect to SII and bordered SII at the representation of the distal limbs. The proximal body parts were represented rostrolaterally in PV. Finally, caudal to both SII and PV, an additional representation, VS, shared a congruent border with the distal hindlimb representation of both SII and PV. VS had a crude topography, and receptive fields of neurons in VS were relatively large. Many neurons in VS responded to both somatosensory and auditory stimulation.
Structure of neurons and ganglia of the guinea pig gallbladder: Light and electron microscopic studies
Authors: Cornbrooks Ellen B. , Pouliot Wendy A. , Mawe Gary M.
Published: January 2005

This study was undertaken to examine the morphological features of cells within ganglia of the guinea pig gallbladder, and to examine the ultrastructure of the ganglionated plexus. Gallbladder neurons are large, with a relatively simple form, having only one or two major processes. Neurobiotin often filled axons to their varicose arbors on smooth muscle in close proximity to the interganglionic connectives. With the exception of connective tissue clefts that sometimes penetrated into them, ganglia were devoid of intercellular spaces, capillaries, or connective tissue elements such as collagen and basal laminae. However, ganglia were surrounded by a single, continuous basal lamina that was enclosed within a fibroblast and collagen capsule. Within ganglia, neurons were insulated by the processes of cells that resembled the astrocyte‐like glia of enteric ganglia. Although few classical synapses were observed, numerous sites of direct apposition were identified between vesicle‐rich profiles and processes of gallbladder neurons. Direct appositions between vesicle‐rich profiles and the ganglion‐limiting basal laminae were also observed. Vesiculated profiles contained small clear vesicles and large dense‐core vesicles. Within interganglionic connectives, axons were unmyelinated and were isolated from one another by processes of glia that resembled Schwann cells. As was seen in the ganglia, direct appositions between vesicle‐rich profiles and the connective‐limiting basal laminae were observed.

The results of this study demonstrate that gallbladder ganglia are similar, ultrastructurally, to enteric ganglia in the CNS‐like composition of the neuropil. However, the greater degree of glial investment, lesser degree of innervation, and simpler neurons indicated differences from the enteric nervous system that may be functionally significant.
Neurotrophic activity of interphotoreceptor matrix on human Y79 retinoblastoma cells
Authors: Tombran‐Tink Joyce , Li Anren , Johnson Michael A. , Johnson Lincoln V. , Chader Gerald J.
Published: January 2005

A neurotrophic activity of adult monkey and bovine interphotoreceptor matrix (IPM) was examined by using cultured human Y79 retinoblastoma cells as a model system. The cells were stimulated for 7 days in suspension culture with soluble IPM components and then attached to poly‐D‐lysine substratum. IPMs from both species induced greater than 80% neuronal differentiation of Y79 cell aggregates after 11 days of attachment as adjudged morphologically by the extension of lengthy, neurite‐like processes. Immunocytochemical studies indicate that differentiated Y79 cells had an increased level of expression of neuron‐specific enolase and a concomitant decreased expression of glial fibrillary acidic protein. This neurotrophic activity cannot be ascribed to nerve growth factor, platelet‐derived growth factor, fibroblast growth factor, epidermal growth factor, or transforming growth factor beta. Although the nature of the factor and its cellular source have yet to be characterized, it may be related to a recently described neurotrophic protein secreted by human fetal retinal pigment epithelial cells in culture. Our findings provide evidence supporting the neuroblastic potential of the Y79 cell line and indicate that the IPM contains a potent neurotrophic activity. Such factors may be important to normal differentiation and maintenance of function of the neural retina.
Cholinergic innervation of the cerebellum of rat, rabbit, cat, and monkey as revealed by choline acetyltransferase activity and immunohistochemistry
Authors: Barmack N. H. , Baughman R. W. , Eckenstein F. P.
Published: January 2005

The cholinergic innervation of the cerebellar cortex of the rat, rabbit, cat and monkey was studied by immunohistochemical localization of choline acetyltransferase (ChAT) and radiochemical measurement of regional differences in ChAT activity. Four antibodies to ChAT were used to find optimal immunohistochemical localization of this enzyme. These antibodies selectively labeled large mossy fiber rosettes as well as finely beaded terminals with different morphological characterization, laminar distribution within the cerebellar cortex, and regional differences within the cerebellum.

Large “grape‐like” classic ChAT‐positive mossy fiber rosettes that were distributed primarily in the granule cell layer were concentrated, but not exclusively located in three separate regions of the cerebellum in each of the four species studied: (1) The uvula‐nodulus (lobules 9 and 10); (2) the flocculus‐ventral paraflocculus, and (3) the anterior lobe vermis (lobules 1 and 2). No intrinsic cerebellar neurons were labeled. No cells in either the inferior olive (the origin of cerebellar climbing fibers) or in the locus coeruleus (an origin of noradrenergic fibers) were ChAT‐positive.

Thin, finely beaded axons, similar to cholinergic axons of the cerebral cortex of the rat, were observed in both the granule cell layer and molecular layer of the cerebellar cortex of the rat, rabbit and cat.

The regional differences in ChAT‐positive afferent terminations in the cerebellar cortex was for the most part confirmed by regional measurements of ChAT activity in the rat, rabbit, and cat. The three cholinergic afferent projection sites correspond to regions of the cerebellar cortex that receive vestibular primary and secondary afferents. These data imply that a subset of vestibular projections to the cerebellar cortex are cholinergic.
Distribution of neurotensin immunoreactivity within the human amygdaloid complex: A comparison with acetylcholinesterase‐ and Nissl‐stained tissue sections
Authors: Benzing William C. , Mufson Elliott J. , Jennes Lothar , Stopa Edward G. , Armstrong David M.
Published: January 2005

In a previous study, we reported marked depletion of neurotensin‐immunoreactivity (NT‐IR) within selected regions of the amygdala of patients with Alzheimer's disease. The significance of these observations was partly obscured largely because we lacked a thorough understanding of the innervation pattern of neurotensin in the normal human amygdala. Accordingly, in the present study, we used a polyclonal antibody against neurotensin to characterize the distribution and morphology of neurotensin‐immunoreactive neuronal elements within the human amygdaloid complex. NT‐IR occurred in a topographic manner that respected the cytoarchitectural boundaries of the amygdaloid subregions as defined by Nissl staining and acetylcholinesterase histochemistry. Most NT‐IR in the amygdala was contained within beaded fibers and dot‐like puncta. Within the subnuclei of the amygdala, immunoreactive neuritic elements were most dense within the central nucleus followed by the medial nucleus and intercalated nuclei. The anterior amygdaloid area, basal complex, paralaminar nucleus, cortical nucleus, cortical‐amygdaloid transition area, and amygdalohippocampal area contained moderate densities of immunoreactivity. The accessory basal and lateral nuclei exhibited scant NT‐IR. Immunoreactive neurons were found only within the anterior amygdaloid area and the central, medial, intercalated, and lateral capsular nuclei. The distribution of NT‐immunoreactive processes and cell bodies within selected regions of the amygdala provides an anatomical substrate that may explain, in part, the neuromodulatory actions of neurotensin upon autonomic, endocrine, and memory systems.
The hypothalamic paraventricular and lateral parabrachial nuclei receive collaterals from raphe nucleus neurons: A combined double retrograde and immunocytochemical study
Authors: Petrov Theodor , Krukoff Teresa L. , Jhamandas Jack H.
Published: January 2005

Retrograde tracer injections of fluorescein‐ and rhodamine‐labelled latex microspheres centered in the parvicellular zone of the hypothalamic/ paraventricular nucleus and pontine lateral parabrachial nucleus revealed that 36% of the labelled neurons in the dorsal raphe nucleus send collaterals to both structures. These cells were organized in a wellx‐distinguishable cluster within the dorsal raphe nucleus. By combining retrograde tracing with immunocytochemistry, it was found that less than 8% of the doublex‐labelled cells stained positively for serotonin. Of the remaining raphe nuclei that were examined, only the median raphe nucleus contributed a minor nonserotoninergic projection to the paraventricular or lateral parabrachial nuclei. Few of the retrogradely labelled cells in the median raphe nucleus contained both tracers. These results suggest that nonserotoninergic and serotoninergic neurons in the dorsal raphe nucleus, via collateral branching, may simultaneously influence the activity of two central nervous system nuclei involved in autonomic control.
The dorsal, posterodorsal, and ventral tegmental nuclei: A cyto‐ and chemoarchitectonic study in the human
Authors: Huang Xu‐Feng , Törk Istvan , Halliday Glenda M. , Paxinos George
Published: January 2005

In order to verify the existence of the ventral and posterodorsal tegmental nuclei and to extend previous findings regarding the dorsal tegmental nucleus in the human brainstem, studies were conducted using cyto‐ and chemoarchitectonics, and computer reconstruction techniques.

Serial sections of five brainstems from adults with no known neurological disorders were stained for Nissl substance, acetylcholinesterase, and substance P. The topography, cytoarchitecture, and acetylcholinesterase reactivity of the tegmental nuclei were presented in a mini‐atlas depicting sections cut in transverse and sagittal planes. The dorsal and posterodorsal tegmental nuclei were identified fully within the central grey matter while the ventral tegmental nucleus extended across the medial longitudinal fasciculus into the pontine reticular formation. The dorsal tegmental nucleus featured a cell‐poor pericentral part, strongly positive for acetylcholinesterase, and a central part comprised of densely packed small neurons that displayed moderate acetylcholinesterase reactivity and strong substance P‐like immunoreactivity. The posterodorsal tegmental nucleus, located in the same transverse plane as the rostral part of the motor nucleus of the trigeminal nerve, was composed of diffusely arranged small to medium neurons with its neuropil displaying moderate acetylcholinesterase reactivity and strong substance P‐like immunoreactivity. The ventral tegmental nucleus, identified as a prominent structure in the pontine tegmentum immediately rostral to the genu of the facial nerve, contained predominantly large neurons and displayed intensive acetylcholinesterase reactivity and substance P‐like immunoreactivity.

These studies showed that the tegmental nuclei, which displayed distinctive cyto‐ and chemoarchitectonic features, were fully present in adult human brainstem.
Immunohistochemical organization of the ventral lateral geniculate nucleus in the tree shrew
Authors: Agarwala Seema , Günlük Alev Erisir , May Jack G. , Petry Heywood M.
Published: January 2005

The ventral lateral geniculate nucleus (vLGN) of the tree shrew (Tupaia belangeri) was differentiated into multiple subdivisions (dorsal cap, intergeniculate leaflet, parvicellular segment, and internal and external magnocellular laminae, the latter being further divisible into a lateral and medial division) on the basis of retinal projections, immunochemistry, and histochemistry. Retinal projections traced with intravitreal injections of wheat germ agglutinin conjugated horseradish peroxidase revealed direct bilateral input to all subregions of the vLGN, except for the internal magnocellular lamina (which received only contralateral input) and the parvicellular segment (which was not retinorecipient). Furthermore, retinal inputs clearly distinguished the relatively heavily retinorecipient intergeniculate leaflet from the less prominently labeled dorsal cap. Immunohistochemical localization of Neuropeptide Y (NPY) perikarya revealed their prominence in the intergeniculate leaflet and the external magnocellular laminae with a concentration along the optic tract. NPY immunoreactive fibers were seen in all but the parvicellular subregion. Gamma amino butyric acid immunoreactivity was seen throughout the vLGN, but was most concentrated in the dorsal cap and the magnocellular laminae, followed by the intergeniculate leaflet. Histochemical studies of cytochrome oxidase and nicotinamide adenosine dinucleotide phosphate (NADPH)‐diaphorase localization revealed similar patterns of dense reactivity within the external magnocellular lamina, intergeniculate leaflet and dorsal cap, and somewhat less dense, but substantial reactivity in the internal magnocellular lamina. Within the external magnocellular lamina, cells reactive for cytochrome oxidase were noted in the lateral portion bordering the optic tract, whereas those specific for NADPH‐diaphorase were dispersed throughout the lamina. Poor reactivity for both histochemical markers was evident in the parvicellular segment. Overall, the markedly different patterns of retinal input and neurochemical organization between the subdivisions of the tree shrew vLGN suggest their involvement in diverse functions. Furthermore, the basic similarity of the organization of the tree shrew vLGN to that of the taxonomically unrelated ground squirrel may indicate a common mammalian scheme.
Changes in size and dendritic arborization patterns of adult cat spinal α‐Motoneurons following permanent axotomy
Authors: Brännström Thomas , Havton Leif , Kellerth Jan‐Olof
Published: January 2005

This study was performed to analyse quantitatively the changes in dimensions and dendritic branching patterns of adult cat spinal α‐motoneurons following permanent axotomy, i.e., in a situation in which the transected motoraxons are prevented from reinnervating their peripheral target muscle. After transection and ligation of the medial gastrocnemius nerve of adult cats, homonymous α‐motoneurons were intracellularly labelled with horseradish peroxidase and subjected to quantitative light microscopic analyses. The cell bodies and proximal dendrites were studied at 3, 6, and 12 weeks after the axotomy. An initial increase in cell body size at 3 weeks was followed by a gradual return towards normal values. The mean diameter of the stem dendrites was decreased at all time periods studied, and the combined diameter of the stem dendrites was reduced at 12 weeks after the axotomy. Entire dendritic trees were reconstructed at 12 weeks postoperatively, and the regression equations describing the correlations between dendritic stem diameter, on one hand, and the size of the entire dendrite, on the other, were used to calculate the total dendritic length, volume, and membrane area of whole axotomized motoneurons. The dendritic branching patterns were also analysed. In comparison with normal medial gastrocnemius α‐motoneurons, the dendritic membrane area and volume of the axotomized cells had decreased by 36% and 29%, respectively, at 12 weeks after the axotomy. This reduction in dendritic size was due to a loss of preterminal and terminal dendritic segments. Abnormal dendritic elongations were observed in 2 of 16 completely reconstructed dendrites.
Ultrastructural studies of retinal, visual cortical (area 17), and parabigeminal terminals within the superior colliculus of Galago crassicaudatus
Authors: Feig Sherry , Van Lieshout David P. , Harting John K.
Published: January 2005

The morphology and synaptic relationships of anterogradely labeled retinal, visual cortical (area 17), and parabigeminal terminals have been analyzed within the superficial gray (stratum griseum superficiale) of Galago crassicaudatus.

Our data regarding the retinocollicular projection reveal two populations of terminals based upon size. The population of smaller terminals are found in clusters, while the larger occur in isolation. Both populations of retinocollicular terminals form synapses primarily with dendritic spines, but synapses upon pale vesicle filled (PVF) profiles and dendritic shafts also occur.

Corticotectal terminals contain round vesicles and make asymmetrical synapses, primarily onto dendritic spines; few form synapses with PVF profiles. Our findings suggest the possibility that there are two populations of corticotectal terminals based upon differences in size and morphology.

Parabigeminotectal profiles contain densely packed round vesicles and make asymmetrical synapses. These terminals, which are exclusively cholinergic in Galago, are presynaptic to dendrites of various sizes.

Convergence of retinal and cortical terminals has been observed. This convergence occurs on distinctly separate regions of the postsynaptic membrane. In contrast, convergence of retinal and parabigeminal terminals occurs on the same region of the postsynaptic cell(s). © 1992 Wiley‐Liss, Inc.
Patterns of GABAergic immunoreactivity define subdivisions of the mustached bat's medial geniculate body
Authors: Winer Jeffery A. , Wenstrup Jeffrey J. , Larue David T.
Published: January 2005

The anatomy and the spatial distribution of neurons and axonal endings (puncta) immunoreactive for glutamic acid decarboxylase (GAD) or gamma‐aminobutyric acid (GABA) were studied in the medial geniculate body of the mustached bat (Pteronotus parnellii). The principal findings are that: 1) most GABAergic neurons are present in the dorsal and ventral divisions with few, if any, in the medial division; 2) only a small fraction, about 1% or less, of auditory thalamic neurons are immunopositive; 3) the density of immunoreactive puncta is independent of the number of GABAergic neurons in the thalamic divisions, with the ventral division having the largest number/unit area, the medial division about 75% of this value, and the dorsal division only about 50%; and 4) the form of the puncta was unique to each division, those in the ventral division being medium‐sized and comparatively simple, those in the medial division predominantly large, coarse, and complex, while dorsal division endings were finer and more delicate. These patterns recapitulate, with some significant exceptions, those found in the rat and cat.

The puncta could originate from several sources; while many may arise from intrinsic GABAergic Golgi type II local circuit neurons, these cells may not be the only or even the principal source. Thus, the dorsal division contains comparatively many immunopositive cells though fewer puncta than might be expected if the bulk of these were to arise from auditory thalamic interneurons. This suggests that other, extrinsic sources, such as the thalamic reticular nucleus, may be the source of such endings. A second point is that the form and density of the puncta is regionally specific within the medial geniculate complex. These local patterns might have a significant and regionally specific role in controlling the differential excitability of auditory thalamic neurons. The distribution of presumptive synaptic endings also has implications for the number and arrangement of glomeruli or synaptic nests. Thus, these circuit elements, which are common to the thalamic nuclei in other species, might play an important role in local synaptic circuits between different types of cells. If so, then the structural variations embodied in these patterns could subserve functional arrangements that differ among species. Such patterns might reflect concomitant physiological differences in the organization of local circuits within the microchiropteran medial geniculate body. © 1992 Wiley‐Liss, Inc.
The melanin‐concentrating hormone system of the rat brain: An immuno‐ and hybridization histochemical characterization
Authors: Bittencourt J. C. , Presse F. , Arias C. , Peto C. , Vaughan J. , Nahon J.‐L. , Vale W. , Sawchenko P. E.
Published: January 2005

In addition to a nonadecapeptide homologous to the teleost melanin‐concentrating hormone (MCH), the amino acid sequence predicted from a rat prepro‐MCH (ppMCH) cDNA suggested that at least one (neuropeptide EI, or NEI), and possibly a second (NGE), additional neuropeptide may be encoded by this precursor. Cross‐reactivity with epitopes of NEI or NGE can account for reported localization of α‐MSH, rat CRF, and human GRF in rat dorsolateral hypothalamic neurons. We have used antisera raised against rat MCH and NEI in immunohistochemical studies at the light and electron microscopic levels, along with hybridization histochemical localization of ppMCH mRNA, to define the organization of this system. As expected, ppMCH mRNA is prominently expressed in cells in the lateral hypothalamic area and zona incerta. The MCH and NEI peptides were extensively colocalized in neurons in both of these areas. In addition, smaller cell groups in the olfactory tubercle and pontine tegmentum were also positively hybridized for ppMCH mRNA and immunostained for MCH and NEI. Fibers stained for MCH and NEI were similarly, and very broadly, distributed throughout the central nervous system in patterns that generally conformed with known projection fields of the lateral hypothalamic area and zona incerta. A differential distribution was seen in at least one region, the interanterodorsal nucleus of the thalamus, which contained a prominent terminal field stained for MCH but not NEI. At the electron microscopic level, MCH‐stained perikarya displayed a prominent staining associated with the Golgi apparatus; this was not encountered in NEI‐stained cells. Both peptides were distributed similarly in terminals in the lateral hypothalamic area and median eminence, with staining associated principally with dense‐cored vesicles. The results suggest that ppMCH‐derived peptides may serve as neurotransmitters or modulators of prominence in a surprisingly expansive projection field of incerto‐hypothalamic neurons. The terminal distributions of this system seem most compatible with functional roles in generalized arousal and sensorimotor integration, processes previously implicated as being subject to modulation by the lateral hypothalamic area. © 1992 Wiley‐Liss, Inc.
Noradrenergic innervation of the thalamic reticular nucleus: A light and electron microscopic immunohistochemical study in rats
Authors: Asanuma C.
Published: January 2005

Fluoro‐ruby injections in the rat locus coeruleus result in scattered chain‐like arrays of varicose anterogradely labeled axons within the thalamic reticular nucleus of rats. An abundant meshwork of axons giving rise to en passant boutons is detected immunohistochemically within this thalamic nucleus by means of an antibody to dopamine‐β‐hydroxylase (DBH). The density of DBH‐positive axonal boutons within the reticular nucleus neuropil is greater than that found in the relay nuclei of the dorsal thalamus (with the exception of the anterior group nuclei). Single DBH‐positive axons appear to contact both proximal and distal dendrites and occasionally the somata of reticular nucleus neurons. Labeled axons are seen closely juxtaposed not only to the swollen segments of the beaded reticular neuron dendrites, but to the constricted segments as well. Electron microscopic examination of DBH‐positive axon terminals within the reticular nucleus neuropil indicates that many of the axonal boutons detected light microscopically participate in asymmetric synaptic contacts. The postsynaptic densities of these synapses are thicker than those of nearby symmetric synapses, but often subtend a shorter length of the postsynaptic membrane than the densities associated with other nearby asymmetric synapses. These observations indicate that the ascending noradrenergic system, in addition to influencing the dorsal thalamus and the cerebral cortex directly, is well situated to influence signal transmission through the nuclei of the dorsal thalamus indirectly via a moderately dense terminal projection upon the thalamic reticular nucleus. Published 1992 by Wiley‐Liss, Inc.
GABAergic and non‐GABAergic projections of accessory optic nuclei, including the visual tegmental relay zone, to the nucleus of the optic tract and dorsal terminal accessory optic nucleus in rat
Authors: Giolli R. A. , Torigoe Y. , Clarke R. J. , Blanks R. H. I. , Fallon J. H.
Published: January 2005

This study examines the non‐γ‐amino butyric acid (GABA)ergic (group I neurons) and GABAergic neurons (group II neurons) of the accessory optic system projecting to the nucleus of the optic tract (NOT)/dorsal terminal nucleus (DTN) of the accessory optic system in rat. These nuclei include the dorsal (MTNd) and ventral (MTNv) divisions of the medial terminal nucleus, the lateral terminal nucleus, the interstitial nucleus of the superior fasciculus, the posterior fibers, and the visual tegmental relay zone. GABAergic neurons of these nuclei that do not target the NOT/DTN (group III neurons) have also been observed. The fluorescent retrograde tracer fluoro‐gold was injected into the pretectum, targeting the NOT/DTN and the tissue prepared immunocytochemically to reveal neurons containing the neurotransmitter GABA.

Three groups of neurons (groups I, II, and III neurons) were examined in terms of their distribution, density, and percentage present. Group I neurons are single‐labeled with fluoro‐gold and represent non‐GABAergic neurons projecting to the NOT/DTN. These neurons are of the highest density in the lateral terminal nucleus (204 neurons/mm2). Their densities are also substantial in the MTNv (120 neurons/mm2), interstitial nucleus of the superior fasciculus, posterior fibers (96 neurons/mm2), and visual tegmental relay zone (93 neurons/ mm2). Group II neurons are double‐labeled with fluoro‐gold and GABA. They form a system of GABAergic neurons projecting to the NOT/DTN, which are exceedingly dense in the MTNd (78 neurons/mm2) but are also dense in both the visual tegmental relay zone (49 neurons/mm2) and MTNv (33 neurons /mm2). Group III neurons are GABAergic neurons that do not target the NOT/DTN but must project to other brain nuclei and/or be interneurons. These are of extremely high concentration in the visual tegmental relay zone (316 neurons/mm2) and are also of substantial densities in the MTNd (77 neurons/mm2), lateral terminal nucleus (72 neurons/mm2), and MTNv (44 neurons/mm2).

The MTNd has the highest percentage of GABAergic neurons projecting to the NOT/DTN (72%). GABAergic neurons also form significant percentages of the projections to the NOT/DTN from the visual tegmental relay zone (34%) and MTNv (21%). The percentage of the total GABAergic neurons that project to the NOT/DTN is the highest in the MTNd (50%) and MTNv (42%). The described GABAergic afferents to the NOT/DTN may function to process information concerned with the compensation for retinal slip. © 1992 Wiley‐Liss, Inc.
Co‐localization of tyrosine hydroxylase, GABA and neuropeptide Y within axon terminals innervating the intermediate lobe of the frog Rana ridibunda
Authors: Tonon Marie‐Christine , Bosler Olivier , Stoeckel Marie‐Elisabeth , Pelletier Georges , Tappaz Marcel , Vaudry Hubert
Published: January 2005

Possible co‐existence of gamma‐aminobutyric acid (GABA), catecholamines, and neuropeptide Y (NPY) in the same nerve terminals of the frog intermediate lobe was investigated by immunocytochemistry at the electron microscopic level. Co‐localization of GABA and tyrosine hydroxylase (TH) was studied by using a double immunogold labeling procedure. Co‐localization of glutamate decarboxylase (GAD) and NPY was studied by combining, respectively, the peroxidase‐antiperoxidase method and a radioimmunocytochemical labeling procedure. Catecholamines and GABA were systematically co‐localized in nerve endings of the pars intermedia. Most of the NPY‐immunoreactive fibers also contained GAD‐like immunoreactivity. However, a few NPY‐positive nerve terminals were not immunoreactive for GAD. These data provide evidence for co‐existence of a regulatory peptide (NPY) and several neuro transmitters (i.e., GABA and catecholamines) within the same axon terminals in the intermediate lobe. Since GABA, dopamine, and NPY have all been shown to inhibit the activity of frog melanotrope cells, the present findings suggest that these neuroendocrine factors may interact either at the pre‐synaptic or post‐synaptic level. © 1992 Wiley‐Liss, Inc.
Substance P immunoreactive boutons form synapses with feline sympathetic preganglionic neurons
Authors: Pilowsky Paul , Llewellyn‐Smith Ida J. , Lipski Janusz , Chalmers John
Published: January 2005

In this study, the relationship between substance P‐immunoreactive boutons and antidromically activated sympathetic preganglionic neurons was examined by light and electron microscopy. Sympathetic preganglionic neurons in the T2–T4 spinal segments of the cat were identified by intracellular recording and antidromic activation from the corresponding white ramus. Neurons were filled with lucifer yellow and then stained to reveal, simultaneously, substance P and lucifer yellow immunoreactivity. All of the neurons examined with the light microscope (n = 13) received appositions from substance P‐immunoreactive boutons. Appositions were found on all parts of the neuron, including the somata, dendrites, and axon initial segment. In most cases (11/13) few close appositions were seen; however, two neurons received large numbers of appositions from substance P‐immunoreactive boutons. On one neuron, 16 substance P‐immunoreactive varicosities that were identified as being closely apposed at the light microscope level were serially sectioned and examined with the electron microscope. Of these 16 varicosities, eight either directly contacted the neuron or formed morphologically identifiable synapses. The remaining eight varicosities were separated from the neuron by thin glial processes. Two other sympathetic preganglionic neurons that were examined ultrastructurally also received substance P‐immunoreactive synapses and close contacts. These findings suggest that substance P‐containing nerve fibres could affect all sympathetic preganglionic neurons but are likely to be important in regulating the activity of only a small proportion of these neurons.
Correlation of filiform hair position with sensory afferent morphology and synaptic connections in the second instar cockroach
Authors: Thompson Kevin S. J. , Blagburn Jonathan M. , Gibbon Charles R. , Bacon Jonathan P.
Published: January 2005

An attempt is made to relate the distribution of filiform hairs on the cercus of the second instar cockroach, Periplaneta americana, to the morphology and patterns of synaptic connectivity of their afferents. We studied the most distal 25 of the 39 filiform hairs which are commonly present. Filiform afferent arborizations were stained by cobalt filling from the cell body in the cercus. Three fundamental arbor types were found, two similar to those of the first instar medial (M) and lateral (L) afferents, and a third, novel type. L‐type arbors could be divided into four subtypes. The most obvious correlate of arbor type is the circumferential position of the hair on the cercus. The proximodistal position of the sensillum within each cereal segment is also a determinant of its arbor. By comparison of hair positions and afferent morphologies, we were able to ascribe homologies between the second instar hairs and members of adult longitudinal hair columns. The patterns of monosynaptic connections between afferents and giant interneurons (GIs) 1, 2, 3, 5, and 6 were determined by recording synaptic potentials in GIs evoked by direct mechanical displacement of individual filiform hairs. Latency from stimulus onset to the rise phase of the first excitatory postsynaptic potential (EPSP) was used as the criterion of monosynapticity. The EPSP amplitudes of the two original L and M afferents are halved in the second instar, in the absence of a significant decrease in GI input resistance. The other afferents can be divided into two basic classes: those which input to GI5 (M‐type), and those which input to GI3 and GI6 (L‐type). The former is correlated with a central or medial position, while the latter is associated with a group of afferents situated laterally on the cercus. In segments 3 and 4, input to GIs 1 and 2 also correlates with a medial cereal position, however, in the more proximal segments 5 and 6, afferents at all positions input to these interneurons. The occurrence of afferents of identical morphology and similar connectivity in equivalent positions in different segments suggests that each sensory neuron is determined by its two‐dimensional position within a segment. The presence of afferents with the same morphology which display proximodistal differences in synaptic connectivity, and of other afferents which have M‐type connectivity despite L‐type morphology, means that anatomy is generally a poor predictor of synaptic connectivity.
Effect of bilateral tectum lesions on retinal ganglion cell morphology in rats
Authors: Bähr Mathias , Wizenmann Andrea , Thanos Solon
Published: January 2005

We have examined morphological changes of retinal ganglion cells (RGCs) during postnatal development in albino rats. Somatic diameter, dendritic field diameter, and branching frequencies of RGCs of normal rats were compared with those of animals that had received bilateral lesions of the tectum immediately after birth. Bilateral lesions of the tectum at P1 (first postnatal day) induced a dramatic increase in RGC death during the time of naturally occurring cell death in the first postnatal week. RGC densities in adult experimental animals were found to be reduced to about 55% of normal. RGCs of normal and operated animals were retrogradely stained with crystals of the fluorescent dye DiI, which was applied to the optic disc of flat mounted and fixed retinae. In normal rats, the somatic and the dendritic field diameters of the RGCs increased and the branching frequency of type I and III RGCs decreased from P1 to P14. By P14, neither the somatic diameter nor the dendritic field size had yet reached adult values and the branching frequencies were still higher than those of adult rat RGCs.

In animals with bilateral lesions of the tectum, all cell types showed an increase in somatic sizes, and in type I and II RGCs an expansion of dendritic territories could be observed. The branching frequencies, however, were significantly lower than those of normal rats of the same age. The dendritic morphology in type III RGCs in operated animals was not significantly different from controls.

These findings demonstrate a potential plasticity of type I and II RGCs, which respond to a loss of neighbouring cells by expansion of their dendritic field during postnatal development.
Immunoreactivity to GABAA receptor in the outer plexiform layer of the cat retina
Authors: Vardi Noga , Masarachia Patricia , Sterling Peter
Published: January 2005

The distribution of GABAA receptor in the outer plexiform layer of cat retina was studied by immunocytochemistry with monoclonal antibodies. Staining was observed at the base of the cone pedicle, extracellularly, in association with the “triad” synaptic complex. Some bipolar dendrites and the basal processes that interconnect the cone pedicles were also stained. Rod spherules and horizontal cells were negative. The findings support the idea that the cone horizontal cells are GABAergic.