bluuebunny/crossref_metadata_2025 huggingface dataset:
Neurotransmitters in the nervous system of Macoma balthica (Bivalvia)
Authors: Karhunen Tuula , Airaksinen Matti S. , Tuomisto Leena , Panula Pertti
Published: January 2005

The distribution of histamine‐, octopamine‐, gamma‐aminobutyric acid‐ (GABA) and taurine‐like immunoreactivity in the bivalve mollusc Macoma balthica was studied immunocytochemically with antisera produced in rabbits. Histamine levels in the ganglia and whole animals were also measured by high‐performance liquid chromatography using a postcolumn derivatization method. Immunoreactivity for these substances, except for taurine, is found in the central nervous system of this species. The most extensive neuronal system is revealed with the antiserum against histamine. All the main ganglia contain histamine‐immunoreactive cell bodies, and a dense network of nerve fibers is seen in the ganglia and nerve roots. Histamine‐immunoreactive nerve fibers project to the mantle edge, lips and oesophagus. The basal part of the inhalant siphon is rich in histamine‐immunoreactive fibers. Unlike histamine, octopamine‐ and GABA‐like immunoreactivities are restricted to the central nervous system. Taurine‐like immunoreactivity is not found in the nervous system of this species. In the nervous system, histamine‐immunoreactive cell bodies and fibers are more numerous than those that are octopamine‐ and GABA‐immunoreactive. The distribution of these substance in the ganglia is different. GABA‐immunoreactive cells are typically smaller than most of the histamine‐ and octopamine‐immunoreactive cells. Most GABA‐ and octopamine‐immunoreactive cells and fibers are located in the pedal ganglion. Histamine is distributed more evenly in the ganglia and nerve roots. The biochemical measurements of histamine correlate well with the immunohistochemical findings and confirm the predominant location of the amine in the nervous tissue. These results suggest that histamine is more widespread than some other putative transmitters, and support the concept that histamine may have an important role in many physiological processes in molluscs. © 1993 Wiley‐Liss, Inc.
Distribution and colocalization of choline acetyltransferase immunoreactivity and NADPH diaphorase reactivity in neurons within the medial septum and diagonal band of broca in the rat basal forebrain
Authors: Kitchener P. D. , Diamond J.
Published: January 2005

NADPH diaphorase histochemistry and choline acetyltransferase immunocytochemistry were used to assess quantitatively the presence of nitric oxide synthase in the cholinergic neurons ofthe magnocellular basal forebrain complex. Virtually all (97%) NADPH diaphorase reactive magnocellular neurons in the medial septum and the vertical and horizontal limbs of the diagonal band of Broca were choline acetyltransferase immunoreactive, whereas only a proportion ofthe choline acetyltransferase immunoreactive neurons were NADPH diaphorase reactive. Thus NADPH diaphorase histochemistry identified a population ofthe magnocellular cholinergic neurons. Occasionally, NADPH diaphorase reactive neurons were observed within the medial septum and diagonal band of Broca that were not choline acetyltransferase immunoreactive, and in general were morphologically distinct from the magnocellular neurons; such neurons are probably representatives within the medial septum and diagonal band of more widely distributed phenotypically distinct populations of NADPH diaphorase reactive neurons. The proportions of the neurons in which choline acetyltransferase and NADPH diaphorase colocalized in the medial septum and in the diagonal bands of Broca were similar in any one coronal section, but there was a considerable difference in the proportions throughout the rostrocaudal extent oi these nuclei. In the most rostral sections of the medial septum and diagonal band, approximately 70% of the choline acetyltransferase immunoreactive neurons were NADPH diaphorase reactive, whereas the proportion decreased progressively to about 30% at the level ofthe decussation ofthe anterior commissure. To examine further the extent of colocalization throughout the magnocellular basal forebrain complex, sections ofthe magnocellular preoptic nucleus, substantia innominata, and nucleus basalis magnocellularis were examined. While there was little total colocalization of choline acetyltransferase immunoreactivity and NADPH diaphorase reactivity in any particular section (approximately 18%), almost all of the double labelied neurons were in the substantia innominata, with very few in the other nuclei. Thus although there is a caudal to rostral gradient of the proportion of magnocellular cholinergic neurons that are NADPH diaphorase reactive throughout the entire basal forebrain magnocellular complex, subregions, such as the substantia innominata and magnocellular preoptic nucleus, may not follow this trend. The recent demonstration that the NADPH diaphorase histochemical reaction localizes a nitric oxide synthase suggests that attention should be given to the NADPH diaphorase Subpopulation ‐in pathological and experimentally induced alterations of the basal forebrain. © 1993 Wiley‐Liss, Inc.
Retinotopic orgarnzation of the primary visual cortex of flying foxes (Pteropus poliocephalus and pteropus scapulatus)
Authors: Rosa Marcello G. P. , Schmid Leisa M. , Krubitzer Leah A. , Pettigrew John D.
Published: January 2005

The representation of the visual field in the occipital cortex was studied by multiunit recordings in seven flying foxes (Pteropus spp.), anesthetized with thiopentone/N2O and immobilized with pancuronmm bromide. On the basis of its visuotopic organization and architecture, the primary visual area (VI) was distinguished from neighboring areas. Area VI occupies the dorsal surface ofthe occipital pole, as well as most of the tentorial surface of the cortex, the posterior third ofthe mesial surface of the brain, and the upper bank of the posterior portion ofthe spiemai sulcus. In each hemisphere, it contains a precise, visuotopically organized representation of the entire extent of the contnateral visual hrmifield. The representation of the vertical meridian, together with 8–15° of ipsilateral hemifield, forms the anterior border of VI with other visually responsive areas. The representation of the horizontal meridian runs anterolateral to posteromedial, dividing VI so that the lower visual quadrant is represented medially, and the upper quadrant laterally. The total surface area of VI is about 140 mm2 for P. poliocephalus, and 110 Ill∼ for P. scapulattlS. The representation of the central visual field is greatly magnified relative to that ofthe periphery. The cortical magnification factor decreases with increasing eccentricity, following a negative power function. Conoversely, receptive field sizes increase markedly with increasing eecentricity, and therefore the point‐image size is approximately constant throughout VI. The emphasis in the representation of the area centralis m VI is much larger than that expected on the representation of the area flat‐mounted retinas. Thus, a larger degree of convergence occurs at the peripheral representations in the retino‐geniculo‐Gortical pathway, in comparison with the central representations. The marked emphasis in the representation of central vision, the extent of the binocular field of vision, and the relatively large surface area of VI reflect the importance of vision in megachiropterans. © 1993 Wiley‐Liss, Inc.
Distinct subsets of sensory olfactory neurons in mouse: Possible role in the formation of the mosaic olfactory projection
Authors: Key Brian , Akeson Richard A.
Published: January 2005

The axons of the primary sensory olfactory neurons project from the olfactory neuroepithelium lining the nasal cavity, onto glomeruli covering the surface of the olfactory bulb. Neuroanatomical studies have shown previously that individual olfactory glomeruli are innervated by neurons that are dispersed widely within the nasal cavity. The aim of the present study was to test the hypothesis that phenotypically unique subsets of primary sensory olfactory neurons, scattered throughout the nasal cavity, project to a subset of glomeruli in specific olfactory bulb loci. Immunochemical and histochemical analyses in neonatal mice revealed that the plant lectin, Dolichos biflorus agglutinin, bound to a subset of mature primary sensory olfactory neurons which express the olfactory marker protein. This subset of neurons was principally located in the rostromedial and dorsal portions of the nasal cavity and projected specifically to a subset of glomeruli in the rostromedial and caudodorsal portions of the olfactory bulb. Analysis of Dolichos biflorus‐reactive axons revealed that these axons coursed randomly, with no evidence of their selective fasciculation, within the olfactory nerve. It was only at the level of the rostral olfactory bulb that a significant reorganisation of their trajectory was observed. Within the outer fibre layer of the bulb, discrete bundles of lectin‐reactive axons began to coalesce selectively into fascicles which preferentially oriented toward the medial side of the olfactory bulb. These data demonstrated that a phenotypically distinct subset of primary sensory olfactory neurons exhibits a topographical projection from the olfactory epithelium to the olfactory bulb, and suggests that these, and other subsets, may form the basis of the mosaic nature of this pathway. Moreover, it appears that the outer nerve fibre layer in the rostral olfactory bulb plays an important instructive role in the guidance and fasciculation of olfactory sensory axons. © 1993 Wiley‐Liss, Inc.
Regional specificities in the distribution, chemical phenotypes, and coexistence patterns of neuropeptide containing nerve fibres in the human anal canal
Authors: Hörsch Dieter , Fink Thorsten , Büchler Markus , Weihe Eberhard
Published: January 2005

Despite the pivotal clinical significance of the human anal canal, little is known about its total and specific innervation. This study assessed the comparative distribution and histotopology of nerve fibres immunoreactive for neural markers and a variey of regulatory active neuropeptides in the human anal canal by light microscopic immunohistochemistry. Depending on the epithelial zone and region of the anal canal, the neural elements were differentially immunoreactive for the pan‐neural marker protein gene product 9.5, the catecholamine marker tyrosine hydroxylase, the neuroendocrine marker chromogranin A, and various neuropeptides. Protein gene product 9.5‐immunoreactive nerve fibres were ubiquitously abundant in the anal canal. In the anal transitional zone, ectopic epithelial types were supplied by the same pattern of peptidergic nerves as the respective type of epithelium in normotopic location. In the dermis of the squamous zone and in the perianal epidermis, unusual distribution patterns of nerve fibres, referred to as areas of high nerve fibre density, were encountered. Double immunohistochemistry revealed region‐specific coexistence patterns of neuropeptidergic nerve fibres, and novel peptide coexistence patterns were detected in anal nerve fibres. Subsets of nerve fibres formed close spatial relationships with chromogranin A‐positive neuroendocrine cells, most frequently in the anal transitional zone. Chromogranin‐A positive cells were shown to be present in the epithelium of perianal eccrine sweat glands. The differential distribution, peptide phenpotypes and coexistence patterns of different nerve fibre populations in the human anal canal may reflect topospecific regulatory functions of neurally released neuropeptides in health and disease. © 1993 Wiley‐Liss, Inc.
Immunocytochemical localization of glycine receptors in the mammalian retina
Authors: Grünert Ulrike , Wässle Heinz
Published: January 2005

The distribution of glycinergic synapses in the mammalian retina was studied with monoclonal antibodies against glycine receptors and a glycine receptor‐related protein (gephyrin). Monoclonal antibody 2b is specific for the α1 subunit of the glycine receptor; monoclonal antibody 4a is specific for all known α subunits and the β subunit, and monoclonal antibody 7a is specific for gephyrin.

The three antibodies were applied to the retina of cat, macaque monkey, rat, and rabbit. The general staining pattern is comparable in all these species and it is similar but distinct with all of the three antibodies. Labeling is characterized by a punctate appearance indicating that it occurs at synapses. In the inner plexiform layer, labeling is concentrated in two bands. One band is located close to the inner nuclear layer; the other band is located in the middle of the inner plexiform layer. In the outer plexiform layer, sparse punctate labeling is seen.

The distribution of gephyrin was also studied at the ultrastructural level in cat and monkey retina. Gephyrin is present on the postsynaptic membrane of amacrine cells and ganglion cells. The presynaptic profile to gephyrin immunoreactivity is always of an amacrine cell. The AII amacrine cell, the crucial glycinergic interneuron of the rod pathway, is presynaptic to gephyrin immunoreactivity in the OFF‐sublamina and is itself gephyrin‐positive at an input synapse from another (possibly GABAergic) amacrine cell in the ON‐sublamina. © 1993 Wiley‐Liss, Inc.
Location and completeness of reinnervation by two types of neurons at a single target: The feline muscle spindle
Authors: DeSantis Mark , Norman Wesley P.
Published: January 2005

Muscle spindles from the tenuissimus muscle of the cat were examined microscopically to assess the precision and completeness of reinnervation of intrafusal muscle fibers by efferent and afferent neurons. Positions of motor and sensory nerve terminals were charted relative to the cross‐sectional area enclosed by the outer capsule of the spindle. Profiles of nerve endings were measured for normally innervated and reinnervated spindles. The tenuissimus was deprivedof innervation by freezing its nerve, sometimes in conjunction with either spinal ganglion removal or ventral rhizotomy. Sensory and motor terminals occupied separate locales along the length of normal muscle spindles. Nerve terminals of efferent and afferent neurons were located in appropriate positions along the length of spindles when axons of both types of neurons regrew‐together and when either category of axon regenerated alone. Precise reinnervation of muscle spindles occurred in spite of a diminished diameter of intrafusal fibers. Repopulation of the spindle with motor endings was less complete than that by sensory endings, based on the proportion and size of the regenerated terminals. We conclude that under optimal conditions for axonal regrowth, efferent and afferent neurons reinnervate their respective regions along intrafusal muscle fibers but motor lags sensory reinnervation within the spindle. The mechanism by which positional specificity happens during reinnervation of intrafusal fibers requires neither an interaction between terminals of the two types of neurons nor target cells of normal bulk. © 1993 Wiley‐Liss, Inc.
Crossed receptive field components and crossed dendrites in cat sacrocaudal dorsal horn
Authors: Gladfelter Wilbert E. , Millecchia Ronald J. , Pubols Lillian M. , Sonty Ramana V. , Ritz Louis A. , Covalt‐Dunning Dorothy , Culberson James , Brown Paul B.
Published: January 2005

The hypothesis that sacrocaudal dorsal horn neurons with crossed receptive field components on the tail have dendrites which cross to the contralateral dorsal horn was tested in a combined electrophysiological and morphological study. Dorsal horn cells in the sacrocaudal spinal cord of anesthetized cats were penetrated with horseradish peroxidase‐filled microelectrodes. After mapping their low threshold mechanoreceptive fields, cells were iontophoretically injected with horseradish peroxidase.

A sample of 16 well‐stained cells was obtained in laminae III and IV. Cells with receptive fields crossing the dorsal midline of the tail (n ‐ 8) had somata in the lateral ipsilateral dorsal horn, and some of these cells (5/8) had dendrites which crossed to the lateral contralateral dorsal horn. Cells with receptive fields spanning the ventral midline (n ‐ 2) were located near the center of the fused dorsal horn, and one of these had bilateral dendrites in this region. Cells with receptive fields on the lateral tail, crossing neither the dorsal nor the ventral midline (n ‐ 6), had cell bodies in the middle of the ipsilateral dorsal horn; half had only ipsilateral dendrites, and half had crossed dendritic branches.

Although the relationship between cell receptive field (RF) location (RF center, expressed as distance from tips of toes) and mediolateral location of the cell body was statistically significant, the correlation between crossed RF components and crossed dendritic branches was not significant. © 1993 Wiley‐Liss, Inc.
Neuropeptide Y immunoreactivity identifies a group of gamma‐type retinal ganglion cells in the cat
Authors: Hutsler Jeffrey J. , White Cheryl A. , Chalupa Leo M.
Published: January 2005

Ganglion cells within the cat retina have been traditionally grouped by morphological criteria into three major classes: alpha, beta, and gamma. The gamma‐type cells have been least well characterized, but the available evidence indicates that this class comprises a relatively heterogeneous population of neurons. In the present study we demonstrate that an antibody for neuropeptide Y (NPY) recognizes a subpopulation of about 2,000 gamma‐type ganglion cells.

The NPY‐immunoreactive (IR) neurons project to the superior colliculus and to the C layers of the lateral geniculate nucleus as demonstrated by retrograde labeling with fluorescent tracers (fluorogold or rhodamine latex microspheres). Virtually all of these cells disappear following lesions of the optic nerve. The NPY‐IR ganglion cells were identified as gamma cells on the basis of soma size and dendritic branching patterns. The somas of these neurons are small (8–22 μm in diameter), and each cell is characterized by sparsely branching dendritic processes, usually extending into the middle third of the inner plexiform layer, the physiologically defined ON sublamina. These neurons are distributed across the entire retina, with the highest density at the area centralis. Within local regions of the retina, however, there was no indication that the NPY‐IR gamma cells are arrayed in a regular mosaic pattern. These results provide the first evidence that the gamma class of ganglion cells of the cat retina can be subdivided on the basis of immunocytochemical properties. © 1993 Wiley‐Liss, Inc.
Antennular projections to the midbrain of the spiny lobster. III. Central arborizations of motoneurons
Authors: Schmidt Manfred , Ache Barry W.
Published: January 2005

The central organization of antennular motoneurons in the brain of the spiny lobster, Panulirus argus, was analyzed by combining biocytin backfills with serial reconstructions of the antennular nerves and the brain. Eighty‐nine to 99 antennular motoneurons occur in each hemibrain. The somata of the motoneurons are distributed in a consistent pattern in two complex soma clusters, the ventral paired mediolateral cluster of the deutocerebrum and the dorsal unpaired median cluster of the tritocerebrum. The motoneurons arborize ipsilaterally in the lateral and median antennular neuropils and the tegumentary neuropil. The backfills indicate a minimum of five morphological types of motoneurons with different arborization patterns. The innervation pattern of the motoneurons, together with previously reported innervation patterns of antennular sensory afferents, suggest that the lateral antennular neuropil is a lower motor center driving local antennular reflexes in response to chemical and mechanical stimulation of the antennule, whereas the median antennular neuropil is a lower motor center for equilibrium responses. © 1993 Wiley‐Liss, Inc.
Cortical axon trajectories and growth cone morphologies in fetuses of acallosal mouse strains
Authors: Ozaki Hiroki S. , Wahlsten Douglas
Published: January 2005

Hereditary absence of the corpus callosum (CC) provides an ideal experiment of nature for exploring mechanisms of axon guidance. In this study the prenatal development of CC axons in the acallosal mouse strains BALB/cWah1 and 129/ReJ or J was compared with normal hybrid mice by using the lipophilic dyes Dil and DiA. A few l/LnJ mice were also examined. The time of emergence and growth rate of CC axons from four cortical regions (frontal, parietal, temporal, occipital) were normal in acallosai strains. Their CC axons arrived at midplane on schedule but then often looped back to form the longitudinal Probst bundle. The frequency of formation of the Probst bundle was highest for axons from frontal cortex, which arrived at midplane first, and lowest for occipital axons, which arrived last. Once a few CC axons found a path to the other side via the hippocampal commissure, those that arrived later then crossed relatively normally. Some axons from the Probst bundle also managed to traverse midine in this manner. When no CC axons crossed, almost all of them entered the Probst bundle and eventually left it within a few hours to proceed in the ipsilateralwhite matter, never turning back toward midplane. Growth cones approaching midplane ipsilaterally and those that had crossed midline and entered contralateral white matter, as well as CC axons in the Probst bundle, expressed a normal range of size and complexity. These results demonstrate that the problem with callosal agenesis resides not in the cells of origin or the axons or growth cones themselves but in the Substrates of axon guidance at the midsagittal plane. © 1993 Wiley‐Liss, Inc.
Spinal projections of pelvic visceral afferents of the rat: A calcitonin gene‐related peptide (CGRP) immunohistochemical study
Authors: Chung Kyungsoon , Lee Won T. , Park Mae J.
Published: January 2005

Little information is available concerning the pelvic visceral afferent system, in view of its terminal location in the spinal cord and its associated transmitter substances in the rat. By utilizing an immunostaining method to examine the transneuronal neurotransmitter depletion resulting from peripheral sensory nerve injury, the spinal projections of primary afferent fibers containing calcitonin gene‐related peptide (CGRP) and originating from pelvic viscera were studied in the lumbosacral spinal cord of the rat. After unilateral or bilateral pelvic nerve section, CGRP immunoreactivity in the lumbosacral spinal cord was decreased greatly in the sacral parasympathetic nucleus (SPN), the dorsolateral fasciculus, the medial border of the dorsal horn, the dorsal gray commissure (DGC), and the intermediate gray connecting the SPN and DGC. Fine structural analysis showed that the CGRP‐immunoreactive terminals made synaptic contact with dendrites and, rarely, with somata. Although there was some incidence of a synaptic contact between a CGRP‐IR terminal and a vesicle‐containing profile, definite evidence of axo‐axonal synapse has not been confirmed. These data indicate that CGRP‐containing pelvic visceral primary afferent fibers project to autonomic areas of the lumbosacral spinal cord by way of the pelvic nerve and make synaptic contact with dendrites and somata. © 1993 Wiley‐Liss, Inc.
Chandelier cells in the hippocampal formation of the rat: The entorhinal area and subicular complex
Authors: Soriano Eduardo , Martinez Albert , Fariñas Isabel , Frotscher Michael
Published: January 2005

In the present study we describe the characteristics of the chandelier cells in the rat entorhinal cortex and subicular complex by using the Golgi method and combined Golgi‐electron microscopic techniques. In the entorhinal cortex, chandelier cells were frequently stained in layers II/III. Two types of axonal complexes were noted. One had a preferential horizontal orientation and gave rise to terminals located in the upper portion of layers II/III. The second type of chandelier cell axon was observed in the medial entorhinal area, innervating the entire extent of layers II/III. In the subicular complex, chandelier cells were frequently stained in the parasubiculum, whereas only a few cells were found in the presubiculum. In both subfields, chandelier cell axons were restricted to layers II/III. In the subiculum, most chandelier cells were present in the stratum radiatum, giving rise to a descending axon that branched in the stratum pyramidale. Both the size and morphological features of the chandelier cell terminal portions were found to be region‐specific.

Electron microscopically, the cell body and dendrites of gold‐toned chandelier cells displayed typical features of nonpyramidal cells, such as the presence of nuclear infoldings, symmetric and asymmetric synapses on the cell body, and moderate numbers of axon terminals covering the smooth dendritic surface. Five gold‐toned chandelier cell axonal complexes were analyzed at the fine structural level. In all parahippocampal regions, gold‐labeled axon terminals formed symmetric contacts with axon initial segments. Our results demonstrate the presence, morphological characteristics, and target selectivity of identified chandelier cells in the parahippocampal region of the rat. Together with previous data, these results suggest a wide distribution of this specialized type of cortical interneuron and indicate that it is a constant and essential component of inhibitory circuits in the cerebral cortex. The possible significance of chandelier cells for the circuits linking several subfields of the hippocampal formation is discussed. © 1993 Wiley‐Liss,Inc.
Terminal arborizations of olfactory nerve fibers in the glomeruli of the olfactory bulb
Authors: Hálasz Norbert , Greer Charles A.
Published: January 2005

The glomerulus of the olfactory bulb may serve as a fundamental organizational unit for odor representation. In this context, the axons of olfactory receptor cells with similar response spectra may converge in specific glomerlui. While the topography between the olfactory epithelium and the olfactory bulb glomeruli has been explored, the characteristics of primary afferent terminal fields within glomeruli are poorly understood. To explore this issue, reconstructions of the terminal arbors of single olfactory nerve (ON) fibers within glomeruli were carried out in the rat olfactory bulb at the light microscopic level. Tissue samples prepared with the Golgi‐EM technique resulted in distinct impregnation of limited subsets of individual ON fibers. Following camera lucida reconstruction, quantitative analyses were made on selected sets of ON fibers and on the glomeruli they invaded. Most ON fibers began to arborize only after penetrating the glomeruli to a mean depth of approximately 35.9 μm. The fibers gave rise to a complex arbor of branches that was limited in total length (mean 157.7 μm) and the number of en passant varicosities or terminal enlargements (mean = 8.1). The number of varicosities and terminal boutons was proportional to the total length of branches. Also, there was a statistically significant correlation between the total branch length and the area (μm2) encompassed by the total arbor. The intraglomerular region supplied by the terminal arbor of an individual ON fiber was generally restricted. Given the recent molecular specificity attributed to olfactory receptor cells, this may provide a morphological basis for selective processing of signals encoded by specific receptors in the olfactory epithelium. © 1993 Wiley‐Liss, Inc.
Taste and tactile responsiveness of neurons in the posterior diencephalon of the channel catfish
Authors: Lamb Charles F. , Caprio John
Published: January 2005

Many teleosts possess an enlargement of the ventral diencephalon called the inferior lobe. In ostariophysine species (e.g., carps and catfishes), this region receives ascending fibers from the primary and secondary gustatory centers in the hindbrain. Extracellular unit activity was recorded from identified nuclei in the inferior lobe of the channel catfish to characterize taste and tactile responsiveness from the different nuclei associated with gustatory projections.

Taste responses (to amino acids and nucleotides) were recorded from units in the nucleus centralis (nCLI), nucleus lobobulbaris (caudal portion—nLB, rostrolateral portion—rl nLB, and parvicellular portion—nLBp), and lateral thalamic nucleus (nLT), supporting the proposed gustatory role for these nuclei. Tactile responsiveness was distinct between different nuclei in the caudal inferior lobe. Units from the nCLI and nLB had lower spontaneous activity than those from other nuclei, and typically had receptive fields including the whole extraoral body surface, ipsilaterally. Units from the rl nLB and nLBp had receptive fields, often including both oral and extraoral surfaces, bilaterally, but rl nLB receptive fields typically included the whole body, while those from nLBp units were often restricted to the head and mouth.

The apparent electrophysiological distinction between these nuclei, combined with their different connectivity patterns, suggest that the gustatory nuclei in the inferior lobe of channel catfish are involved in various different sensory processing mechanisms. © 1993 Wiley‐Liss, Inc.
Fiber pathways and branching patterns of biocytin‐labeled olivocochlear neurons in the mouse brainstem
Authors: Brown M. C.
Published: January 2005

Olivocochlear neurons have somata in the superior olivary complex in the brainstem and project fibers to the cochlea. The purpose of the present study was to demonstrate the fiber pathways and branching patterns of olivocochlear fibers within the brainstem. Olivocochlear fibers were labeled by extracellular injections of biocytin into the cochlea of mice. The injections labeled two populations of olivocochlear fibers. Thin olivocochlear fibers arose from small somata of the lateral olivocochlear group located ipsilaterally in the lateral superior olive. Thick olivocochlear fibers arose from larger somata of the medial olivocochlear group located bilaterally in the periolivary nuclei. The lateral olivocochlear and medial olivocochlear fibers had similar courses but differed in their branching patterns. Branches from lateral olivocochlear fibers terminated near their somata of origin in the lateral superior olive or in the lateral vestibular nucleus. Branches from medial olivocochlear fibers terminated in the inferior vestibular nucleus or in the cochlear nuclear complex. A few branches from medial olivocochlear fibers projected to the contralateral side. Although they project primarily to the cochlea, olivocochlear neurons also give off branches to a variety of nuclei in the brainstem, thus involving auditory and non‐auditory nuclei in the olivocochlear reflex system. © 1993 Wiley‐Liss,Inc.
Transient cortical pathways in the pyramidal tract of the neonatal ferret
Authors: Meissirel Claire , Dehay Colette , Kennedy Henry
Published: January 2005

Anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) was used to study transient axons from the visual cortex in the pyramidal tract. Injections at birth restricted to the visual cortex labeled axons in the vicinity of the pontine nuclei. Two to eight days after birth, axons from the occipital cortex were found posterior to the pontine nucleus, their caudalmost stable target. Transient corticospinal axons from the presumptive primary visual cortex did not grow caudal to the pyramidal decussation. Innervation of more distal targets preceded innervation of proximal targets. Innervation of the pontine nucleus is initiated around 68 hours after birth, when the transient extension in the medullary pyramidal tract has attained its maximum caudal extent. Innervation of the superior colliculus begins 9 days after birth.

Retrograde tracers were used to follow the developmental changes in the cortical distribution of the parent neurons giving rise to axons in the pyramidal tract. In the adult, labeled neurons following injection of retrograde tracer in the pyramidal tract occupied less than a third of the neocortex and were centred on the anterior part of the coronal and spleniocruciate gyri. In the immature brain, labeled neurons covered more than two‐thirds of the neocortex. Areal density measurements in the neonate showed that peak labeling was centred in the anterior coronal and spleniocruciate gyri, where corticospinal cells in the adult are located. There was a marked rostral‐caudal gradient so that labeled neurons were very scarce towards the occipital pole.

These results, showing transient neocortical axons in the pyramidal tract in a carnivore, suggest that this may be a common feature of mammalian development. The finding that the adult pattern of corticospinal projections does not emerge from a uniform distribution is discussed with respect to the areal specification of cortical connectivity. © 1993 Wiley‐Liss, Inc.
Recovery of original nerve supply after hypoglossal–facial anastomosis causes permanent motor hyperinnervation of the whisker‐pad muscles in the rat
Authors: Angelov Doychin N. , Gunkel Andreas , Stennert Eberhard , Neiss Wolfram F.
Published: January 2005

Hypoglossal–facial anastomosis (HFA), used in humans for the treatment of facial palsy, was experimentally performed in adult female Wistar rats. The time course of facial reinnervation and the extent of the new motor nerve supply of the vibrissal muscles that develops after HFA were estimated by counting all motoneurons in the brainstem labeled by injection of horseradish peroxidase (HRP) into the whisker pad; muscle innervation by motor endplates was not studied. In untreated animals, HRP injection labels 1,254 ± 54 (mean ± S.D.; n = 6) motoneurons, localized exclusively in the lateral subdivision of the facial nucleus. Immediately following HFA, this number drops to zero. The first HRP‐labeled motoneurons appear in the hypoglossal nucleus at 28 days postoperation (dpo) and at 56 dpo their number reaches 1,096 ± 48. Unexpectedly, the facial nerve, whose proximal stump has been left as blind end during surgery, additionally sends axons to the facial periphery. This resprouting is first detected at 42 dpo with HRP‐marked neurons throughout the facial nucleus lacking somatotopic organiza‐tion. The number of these labeled neurons also rises with time, and at 56 dpo, a total of 1,797 ± 142 facial and hypoglossal motoneurons, that is, 43% more motoneurons than in normal animals, supplies the whisker pad. This hyperinnervation, that is, the projection of more moto‐neurons into the target muscle than under normal conditions‐further increases to 1,978 ± 92 motoneurons at 224 dpo and may provide a new animal model for studying the competitive relationships between motoneurons in their search for peripheral targets. © 1993 Wiley‐Liss, Inc.
Retinal ganglion cells within the foveola of new world (Saimiri sciureus) and old world (Macaca fascicularis) monkeys
Authors: Leventhal Audie G. , Thompson Kirk G. , Liu Dan
Published: January 2005

The morphology and distribution of retinal ganglion cells within the foveola of New World (Saimiri sciureus) and Old World (Macaca fascicularis) monkeys labeled as a result of horseradish peroxidase injections into the dorsal lateral geniculate nucleus were studied. The results indicate that monkey's foveola normally contains significant numbers of retinal ganglion cells. Most of these project ipsilaterally. Cells within the foveola are larger than other cells in monkey central retina; their dendritic fields are up to 50 times larger in area than those of cells in the foveal slope. The dendritic fields of the ganglion cells within the foveola cover at least 70–100% of its area.

Among ganglion cells within the foveola (as in most ganglion cells), there was a strong tendency for the axon and dendritic tree to arise from opposite poles of the soma. The axon‐dendrite axes of ganglion cells within the foveola did not show a consistent pattern. In contrast, the axes of ganglion cells in the transition zone between the foveola and the foveal slope were directed tangentially to the circumference of the fovea. The dendritic coverage of the foveola by retinal ganglion cells suggests functional significance and provides a possible neural basis for 2–3° of bilateral representation of the fovea within the central visual pathways. Alternatively or in addition, these cells may be “remnants of foveation” and provide insight into the developmental processes that mediate the development of the fovea. © 1993 Wiley‐Liss, Inc.
Development of corticotectal synaptic terminals in the cat: A quantitative electron microscopic analysis
Authors: Plummer Kim Lord , Behan Mary
Published: January 2005

We studied the development of corticotectal synaptic terminal boutons and synapses by making injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) into area 17 of visual cortex in kittens ranging from newborn to 12 weeks of age and in adults. The location and extent of the injection site, and labeled corticotectal axon terminals in the superficial layers of the superior colliculus were demonstrated histochemically with the cobalt‐glucose oxidase diaminobenzidine reaction.

During the first 2 weeks after birth, the majority of labeled profiles resembled axonal growth cones, or structures intermediate in morphology between growth cones and synaptic terminals, while very few corticotectal axon terminals forming well‐defined synaptic contacts were observed. Labeled synaptic terminals in kittens at 1 and 2 weeks of age were small, contained very few synaptic vesicles, which were usually restricted to the contact zone, and exhibited few mitochondria. By 4 and 6 weeks after birth, a well‐developed population of synaptic terminals was established; however, growth cones and intermediate profiles were still numerous. At 8 weeks of age synaptic terminals were morphologically mature, and growth cone‐like profiles were no longer observed.

To study quantitative changes in synapse development we used the disector method to obtain unbiased estimates of the density and number of corticotectal synaptic terminals and synapses; both the density and number of terminals and synapses increased steadily throughout postnatal development. These results suggest that the corticotectal projection develops by the progressive elaboration of synapses, as opposed to synapse overproduction and subsequent elimination. © 1993 Wiley‐Liss, Inc.
Topological analysis of the brainstem of the bowfin, Amia calva
Authors: Heijdra Yvonne F. , Nieuwenhuys Rudolf
Published: January 2005

This paper presents a survey of the cell masses in the brainstem of the generalized actinopterygian fish Amia calva, based on transversely cut Nissl‐, Klüver‐Barrera‐, and Bodian‐stained serial sections. This study is intended to serve a double purpose. First it forms part of a now almost complete series of publications on the structure of the brainstem in representative species of all groups of vertebrates. Within the framework of this comparative program the cell masses in the brainstem and their positional relations are analyzed in the light of the Herrick–Johnston concept; according to this the brainstem nuclei are arranged in four longitudinal, functional zones or columns, the boundaries of which are marked by ventricular sulci. The procedure employed in this analysis essentially involves two steps: first, the cell masses and large individual cells are projected upon the ventricular surface, and next, the ventricular surface is flattened out, that is, subjected to a one‐to‐one continuous topological transformation (Nieuwenhuys [1974] J. Comp. Neurol. 156:255‐267). The second purpose of the present paper is to provide a cytoarchitectonic basis for experimental analysis of the fiber connectivity in the brainstem of Amia.

Five longitudinal sulci–the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, and the sulcus lateralis mesencephali–could be distinguished. Some shorter grooves, present in the isthmal region, clearly deviate from the overall longitudinal pattern of the other sulci. Although in Amia most neuronal perikarya are contained within a diffuse periventricular gray, 40 cell masses could be delineated: Eight of these are primary efferent or motor nuclei, 10 are primary afferent or sensory centers, seven are considered to be components of the reticular formation, and the remaining 15 may be interpreted as “relay” nuclei.

The topological analysis yielded the following results. In the rhombencephalon the gray matter is arranged in four longitudinal columns or areas, termed area ventralis, area intermedioventralis, are intermediodorsalis, and area dorsalis. The sulcus intermedius ventralis, the sulcus limitans, and the sulcus intermedius dorsalis mark the bounderies between these morphological entities. These longitudinal areas coincide largely, but not entirely, with the functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the viscerosensory nucleus of the solitary tract, several general somatosensory and special somatosensory nuclei. The four longitudinal zones cannot be distinguished in the mesencephalon nor can the sulcus limitans be recognized here. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extremity of the somatomotor column, whereas the remainder of the midbrain contains a number of somatosensory centers. © 1994 Wiley‐Liss, Inc.
Origin and function of spiral fibers projecting to the goldfish mauthner cell
Authors: Scott John W. , Zottoli Steven J. , Beatty Nicholas P. , Korn Henri
Published: January 2005

Two neuron types contact the Mauthner cell (M cell) in the axon cap, a specialized region of high electrical resistance surrounding the initial segment of the M cell axon. One type produces a mixed electrical and chemical inhibition of the M cell. The second sends axons into the central core of the axon cap, where they spiral around the initial segment making both conventional synapses and gap junction contacts. The origin and synaptic effects of these spiral fibers have not been studied previously.

When goldfish M cells were filled with Lucifer yellow, presynaptic spiral fibers were seen in the axon cap. These fibers could be traced back through the medial longitudinal fasciculus to their somata, near the contralateral fifth nerve motor nucleus. The same somata were labeled by horseradish peroxidase injected extracellularly into the axon cap.

Recordings were made in the axon cap and the M cell after stimulation of hindbrain areas near the spiral fiber somata and axons. Extracellularly, a negative potential was observed close to the termination of the spiral fibers and termed the spiral fiber potential (SFP). Intracellularly, a graded, short latency depolarization of the M cell corresponded to the SFP and could cause the M cell to spike. This depolarization did not shunt the membrane, indicating that it may be produced through gap junctions. Intracellular responses to hindbrain stimulation also had a chloride‐dependent, second component that shunted the membrane during paired‐pulse testing. This inhibitory second component was probably evoked by cells other than the spiral fiber cells themselves. © 1994 Wiley‐Liss, Inc.
Grafts of fetal central nervous system tissue rescue axotomized clarke's nucleus neurons in adult and neonatal operates
Authors: Himes B. Timothy , Goldberger Michael E. , Tessler Alan
Published: January 2005

Many conditions are thought to contribute to neuron death after axotomy, including immaturity of the cell at the time of injury, inability to reestablish or maintain target contact, and dependence on trophic factors produced by targets. Exogenous application of neurotrophic factors and transplants of peripheral nerve and embryonic central nervous system (CNS) tissue temporarily rescue axotomized CNS neurons, but permanent rescue may require transplants that are normal targets of the injured neurons. We examined the requirements for survival of axotomized Clarke's nucleus (CN) neurons. Two months after hemisection of the spinal cord at the T8 segment, there was an ipsilateral 30% loss of neurons at the L1 segment in adult operates and a 40% loss in neonates. Transplants of embryonic spinal cord, cerebellum, and neocortex inserted into the T8 segment at the time of hemisection prevented virtually all of the cell death in both adults and neonates, but transplants of embryonic striatum were ineffective. None of the grafts prevented the somal atrophy of CN neurons caused by axotomy. Retrograde transport of fluoro‐gold from the cerebellum demonstrated that 33% of all CN neurons at L1 project to the cerebellum, 50% of these died following a T8 hemisection, but all these projection neurons were rescued by a transplant of embryonic spinal cord. These results suggest that the rescue of axotomized CN neurons is relatively specific for the normal target areas of these neurons, but this specificity is not absolute and may depend on the distribution and synthesis of particular neurotrophic agents. © 1994 Wiley‐Liss, Inc.
Light and electron microscopic analysis of synaptic development in Macaca monkey retina as detected by immunocytochemical labeling for the synaptic vesicle protein, SV2
Authors: Okada M. , Erickson A. , Hendrickson A.
Published: January 2005

The development of synapses has been followed in Macaca monkey fetal and infant retina using immunocytochemical labeling for the transmembrane synaptic vesicle glycoprotein, SV2. Electron microscopy (EM) was used to verify the presence of morphological synapses at selected ages. EM immunocytochemical labeling in adult retina showed that all synaptic types contained SV2 in inner (IPL) and outer (OPL) plexiform layers. In fetal retina, SV2 expression and the appearance of morphological synapses were closely related in time, demonstrating that SV2 is a reliable marker for synaptogenesis.

SV2 expression appears along a foveal to peripheral gradient. Both SV2 and synapses appear in the foveal IPL at Fd50–55, and reach the retinal edge by Fd90–103. Cone ribbon synapses and SV2 labeling are not present in the foveal OPL until Fd60. Photoreceptors in the far periphery contain SV2 by Fd119–125. This pattern demonstrates an “inner to outer” direction of synaptogenesis. Cones show SV2 labeling before rods at the same retinal eccentricity. In the cone‐dominated fovea, SV2 labeling and bipolar cell ribbon‐containing terminals are present at Fd55 when amacrine cell conventional terminals are very scarce, indicating that bipolar synapses precede amacrine synapses in monkey foveal IPL. SV2 labeling and bipolar terminals appear first in the outer IPL which contains “OFF” ganglion and bipolar processes in the adult, suggesting that “OFF” midget bipolar cells may form the first synapses.

Both SV2 immunocytochemical labeling and EM morphology find that monkey retina follows a generalized inner before outer, and cone before rod synaptic developmental pattern, similar to that in other mammals. The cone‐dominated fovea initiates synaptogenesis, and shows a different synaptic sequence from rod‐dominated peripheral retina. © 1994 Wiley‐Liss, Inc.