bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of monocular enucleation, tetrodotoxin, and lid suture on cytochrome-oxidase reactivity in supragranular puffs of adult macaque striate cortex
Authors: Trusk Thomas C. , Kaboord Wayne S. , Wong-Riley Margaret T.T. 
Published: June 2009

AbstractThe laminar structure and cellular distribution of cytochrome-oxidase (CO) reactivity in supragranular puffs of striate cortex was examined in adult macaque monkeys surviving various periods of monocular enucleation, lid suture, and retinal impulse blockage with tetrodotoxin (TTX). Enucleation and TTX produced a rapid and severe loss in the size of the CO reactive region in puffs dominated by the removed or treated eye compared to slower and less marked reductions obtained in deprived puffs of lid-sutured monkeys. In all deprived animals, the cross-sectional areas of deprived puffs decreased most rapidly in the upper layers (2 and 3A). In long-term enucleated (60 wks) and TTX-treated (4 wks) monkeys, puff area was severely reduced in layer 3B, while reactivity in layer 3B appeared partially spared in lid-sutured monkeys. The density of the CO reaction product was significantly and evenly reduced throughout deprived puffs for all of the monkeys examined; however, this decrease was less severe in adult monkeys lid-sutured for 11 wks. Although no evidence for cell loss was obtained, all three forms of visual deprivation led to lower counts of neuronal perikarya with high levels of CO reaction product in both deprived puff and interpuff areas. This effect was less marked in the deprived puffs of monkeys lid-sutured for 2.5 and 3 yrs, suggesting recovery of CO activity in some neurons. Neurons in deprived puffs and interpuffs were generally similar in size to those in nondeprived regions, although CO-reactive cells were significantly smaller in the deprived puffs of monkeys enucleated for 28.5 or 60 wks. These results indicate that the metabolic response of neuronal elements in supragranular striate cortex depends upon the nature of the visual deficit. The partial sparing of CO reactivity in deprived puffs of lid-sutured monkeys may reflect the continued transmission of certain types of visual stimuli through a closed eyelid.
Immunohistochemical localization of GABAAreceptors in the retina of the new world primateSaimiri sciureus
Authors: Hughes Thomas E. , Carey Russell G. , Vitorica Javier , de Blas Angel L. , Karten Harvey J. 
Published: June 2009

AbstractA large population of amacrine cells in the retina are thought to use GABA as an inhibitory neurotransmitter in their synaptic interactions within the inner plexiform layer. However, little is known about their synaptic targets; the neurons that express the receptors for GABA have not been clearly identified. Recently, the GABAAreceptor has been isolated and antibodies have been raised against it. These antibodies have proven useful for the immunocytochemical localization of the receptor, and two brief reports describing the distribution of GABAAreceptor immunoreactivity in the retina have appeared (Richards et al., 1987; Mariani et al., 1987). We used a monoclonal antibody (62–3G1) against the GABAAreceptor to study the retina of the New World primateSaimiri sciureus.Labeled somata were found in the inner nuclear layer (INL) and ganglion cell layer (GCL). The staining was confined to what appeared to be the cell's plasmalemma and small cytoplasmic granules. Most of the labeled neurons in the INL had small somata (5–7 μm in diameter) located at the vitreal edge of the layer. They arborized in two laminae (approximately 2 and 4) of inner plexiform layer (IPL). Ventral to the optic disc (2.5 mm) they comprised 29% of the cells present. A few of the labeled neurons appeared to be interplexiform cells or flat bipolar cells, with labeled processes that extended into both the IPL and the inner half of the outer plexiform layer. In the GCL, the labeled somata were among the largest present (13–20 μm in diameter), and 2.5 mm ventral to the optic disc they made up 15% of the cells present. Experiments in which immunoreactive somata were retrogradely labeled following the injection of fluorescent tracers into the optic tract provided a conclusive demonstration that some of the immunoreactive somata were ganglion cells. The antibody often labeled their axons in the optic fiber layer. This suggests that the GABAAreceptors are transported anterogradely to the retinal terminal fields. The dendrites of the immunoreactive ganglion cells extended into the 2 laminae of labeled processes in the IPL, and their primary dendritic arbors were, at any given eccentricity, quite similar in appearance. This homogeneity suggests that they comprise a particular subset of the ganglion cells.Sections simultaneously labeled with the monoclonal antibody against the GABAAreceptor and antisera against either L-glutamic acid decarboxylase (GAD) or GABA revealed that the GAD/GABA was distributed much more widely in the IPL than the GABAAreceptor. This variance may reflect either the presence of other, perhaps GABAB, receptors in the IPL or GABA in portions of the IPL where it is ineffective as a neurotransmitter.
Organotypic slice culture of the mammalian retina
Authors: Feigenspan Andreas , Bormann Joachim , Wässle Heinz 
Published: June 2009

AbstractVertical slices of 6-day postnatal (P6) rat retina were cut at a thickness of 100 μm and cultured using the roller-tube technique. After 14–21 daysin vitrothere was significant distortion of normal retinal architecture, but localized areas of the slices showed the typical pattern of layering of mature retina. The following immunocytochemical markers were used to characterize the different retinal cell types: antibodies against protein kinase C (PKC), calcium binding protein (CabP 28kD), neurofilaments (NF), glia-specific antibodies (GFAP, vimentin), and transmitter-specific antibodies (GABA, TH). The expression of these markers was compared in P6 retina, adult retina, and slice culture. To further characterize the cultured cells, patch-clamp recordings were performed in combination with intracellular injection of Lucifer Yellow (LY). Transmitter-and voltage-gated membrane currents were recorded from morphologically identified neurons. The experiments show that a mammalian slice culture can be used to study differentiation and function of retinal cell types.
The histaminergic innervation of the lateral geniculate complex in the cat
Authors: Uhlrich Daniel J. , Manning Karen A. , Pienkowski Thomas P. 
Published: June 2009

AbstractThe histaminergic innervation of the thalamic dorsal and ventral lateral geniculate nuclei and the perigeniculate nucleus of the cat was examined immunohistochemically by means of an antibody to histamine.We find histamine-immunoreactive neurons in the cat brain are concentrated in the ventrolateral portion of the posterior hypothalamus, confirming a previous report. However, this cell group also spreads into medial, dorsal, and extreme lateral regions of the posterior hypothalamus and extends as far rostral as the optic chiasm.Histamine-labeled fibers cover all regions of the lateral geniculate complex, but the density of labeling varies. The ventral lateral geniculate nucleus (vLGN) is most densely labeled, the A laminae of the dorsal lateral geniculate are sparsely labeled, and the geniculate C laminae and the perigeniculate nucleus show intermediate amounts of label. Thus, histaminergic fibers demonstrate a predilection for zones innervated by the W-cell system. Labeled fibers exhibit few branchings and numerousen passantswellings, lending a beaded appearance. The vLGN showed more instances of fibers with larger-sized swellings (up to 2 μm).Following injections of biotinylated tracers into the hypothalamus, we find labeled fibers throughout the lateral geniculate complex. The anterogradely labeled fibers resemblethe histaminergic fibers in morphology, distribution, and relative bouton size. Thus, the hypothalamus appears to be the source of the histaminergic fibers in the lateral geniculate complex.Histamine-labeled fibers in the dorsal lateral geniculate nucleus (dLGN) exhibit uncommon ultrastructural morphology. Many extremely large, round, or elliptical vesicles fill the fiber swellings. Swellings are directly apposed to a variety of other dendritic and axonal profiles, but thus far no convincing synaptic contacts have been seen. The distribution and appearance of these histaminergic fibers resembles those reported for serotonergic fibers.Our results support the idea that histamine works nonsynaptically as a neuromodulator in the lateral geniculate complex, affecting the level of visual arousal.
Selective depletion of beta cells affects the development of alpha cells in cat retina
Authors: Ault Steven J. , Thompson Kirk G. , Zhou Yifeng , Leventhal Audie G. 
Published: June 2009

AbstractThe results of previous studies suggest that class-specific interactions contribute to the development of the different classes of retinal ganglion cells. We tested this hypothesis by examining the morphologies and distributions of alpha (α) cells in regions of mature cat retina selectively depleted of beta (β) cells as a result of visual cortex lesions at birth. We find that α cells in regions of central retina depleted of β cells are abnormally large while α cells in regions of peripheral retina depleted of β cells are abnormally small. The normal central-to-peripheral α cell soma-size gradient is absent in hemiretinae depleted of β cells. The dendritic fields of α cells in the border of β-cell-depleted hemiretina extend preferentially into the β-cell-poor hemiretina. In spite of this, α cell bodies retain their normal retinal distribution and remain distributed in a nonrandom mosaic-like pattern. Thus, it appears that the development of α retinal ganglion cells is influenced by interactions both with other α cells (class-specific interactions) and with surrounding β cells (nonclass-specific interactions).
Brain stem and cortical contributions to the generation of horizontal optokinetic eye movements in humans
Authors: Harris Laurence R. , Lewis Terri L. , Maurer Daphne 
Published: June 2009

AbstractWe evaluated the subcortical pathways’ contribution to human adults’ horizontal OKN by using a method similar to that used previously with cats (Harris & Smith, 1990; Smith & Harris, 1991). Five normal adults viewed plaids composed of two drifting sinusoidal gratings arranged such that their individual directions of drift were 60 deg or more from the direction of coherent motion of the overall pattern. Physiological evidence indicates that under monocular viewing, nasalward coherent motion gives advantage to any crossed subcortical contribution while temporalward coherent motion minimizes it. We recorded horizontal eye movement by infrared reflection and asked subjects to report the perceived direction of motion.During both binocular and monocular viewing, the direction of the slow phase of OKN fell closer to the direction of coherent movement than to that of the oriented components. Monocular viewing produced no nasal-temporal asymmetries in the influence of coherent motion on the direction of OKN. This suggests that in humans the influence of coherent motion is mediated primarily by cortical mechanisms and, unlike in cats, with little or no involvement of subcortical mechanisms in the generation of horizontal OKN.
A second episode of ganglion cell death takes place when an optic nerve regenerates for a second time in the frog
Authors: Beazley L. D. , Darby J.E. 
Published: June 2009

AbstractWe have previously reported that during optic nerve regeneration in the frog, 30–40% of retinal ganglion cells die, the loss being complete within 10 weeks. In the present study, we crushed the optic nerve, waited 10 weeks, and then recrushed the nerve at the same site. Retinae were examined 10 weeks later. We estimated ganglion cell numbers from cresyl-violet-stained wholemounts and found a fall of 53% compared to normals. The loss was significantly greater than the losses of 36% and 35%, respectively, in frogs which received a single optic nerve crush and were examined 10 or 20–24 weeks later. The results indicate that a second episode of ganglion cell death took place when the optic nerve regenerated a second time. We conclude that ganglion cells in the frog are not comprised of two subpopulations, only one of which intrinsically possesses the ability to regenerate.
The segregation of ON- and OFF-center responses in the lateral geniculate nucleus of normal and monocularly enucleated ferrets
Authors: Morgan James , Thompson Ian D. 
Published: June 2009

AbstractWe have investigated the distribution of ON- and OFF-center responses in the lateral geniculate nucleus of ferrets with normal and abnormal retinal projections. Electrophysiological recordings in normal pigmented animals confirm previous studies on mustelids showing that ON-center responses are found in the anterior, inner parts of laminaeAandAIand OFF-center responses in posterior, outer leaflets. In albino animals, laminaAdisplays normal patterns of ON/OFF segregation but in laminaAI, which receives an abnormal crossed retinal projection, no consistent patterns of segregation are found. Following monocular enucleation on the day of birth, the uncrossed projection in pigmented ferrets remains expanded across the LGN. Anatomically and physiologically, this projection is segregated into two leaflets: an anterior, inner ON-center leaflet and a posterior outer OFF-center leaflet. We conclude that the persistence of ON/OFF segregation, independent of geniculate location, suggests that self-sorting of retinal input is an important factor in generating the segregation.
Dendritic competition in the developing retina: Ganglion cell density gradients and laterally displaced dendrites
Authors: Linden Rafael 
Published: June 2009

AbstractDendrites of retinal ganglion cells (RGCs) tend to be distributed preferentially toward areas of reduced RGC density. This, however, does not occur in the retina of normal pigmented rats, in which it has been suggested that the centro-peripheral gradient of RGC density is too shallow to provide directional guidance to growing dendrites. In this study, laterally displaced dendrites of RGCs retrogradely labeled with horseradish peroxidase were related to cell density gradients induced experimentally in the rat retina. Neonatal unilateral lesions of the optic tract produced retrograde degeneration of contralaterally projecting RGCs, but spared ipsilaterally projecting neurons in the same retina. These lesions created an anomalous temporal to nasal gradient of cell density across the decussation line, opposite to the nasal to temporal gradient found along the same axis in either normal rats or rats that had the contralateral eye removed at birth. RGCs in rats that received optic tract lesions had their dendrites displaced laterally toward the depleted nasal retina, while in either normal or enucleated rats there was no naso-temporal asymmetry. The lateral displacement affected both primary dendrites and higher-order branches. However, the gradient of cell density after optic tract lesions was less steep than the gradient in either normal or enucleated rats. To test for the presence of steeper gradients at early stages of development, RGC density gradients were also examined at postnatal day 5 (P5). In normal rats, the RGCs were homogeneously distributed throughout the retina, while rats given optic tract lesions at birth already showed a temporo-nasal density gradient at P5. Still, this anomalous gradient was less steep than that found in normal adults. It is concluded that the time course, rather than the steepness of the RGC density gradient, is the major determinant of the lateral displacement of dendritic arbors with respect to the soma in developing RGCs. The data are consistent with the idea that the overall shape of dendritic arbors depends in part on dendritic competition during retinal development.
Whole-cell currents activated at nicotinic acetylcholine receptors on ganglion cells isolated from goldfish retina
Authors: Yazejian Bruce , Fain Gordon L. 
Published: June 2009

AbstractWe have recorded whole-cell membrane currents in response to exogenously applied acetylcholine (ACh), nicotine, and 1,1 dimethyl-4-phenyl piperazinium iodide on retinal ganglion cells enzymatically dissociated from goldfish retina. Agonist applications induced nicotinic-type responses in a majority of cells when cells were isolated under optimal conditions. Currents were reminiscent of nicotinic-type ganglionic responses. Dose-response measurements of ACh-induced currents indicated an EC50 of 52 μM and a Hill coefficient of 0.6. Currents were selective for Na+ over Cl− and were highly inwardly rectifying. Responses were blocked reversibly by d-tubocurarine, hexamethonium chloride, and N-methyl-D-glucamine. In 50% of the cases, α-bungarotoxin reversibly blocked the current induced by ACh application. The blocking action of mecamylamine was irreversible and independent of the presence of agonist but was more effective in the presence of ACh. We conclude that functional nicotinic ACh receptors exist on most goldfish retinal ganglion cells.
Topography of supplementary eye field afferents to frontal eye field in macaque: Implications for mapping between saccade coordinate systems
Authors: Schall Jeffrey D. , Morel Anne , Kaas Jon H. 
Published: June 2009

AbstractTwo discrete areas in frontal cortex are involved in generating saccadic eye movements—the frontal eye field (FEF) and the supplementary eye field (SEF). Whereas FEF represents saccades in a topographic retinotopic map, recent evidence indicates that saccades may be represented craniotopically in SEF. To further investigate the relationship between these areas, the topographic organization of afferents to FEF from SEF in Macaco mulatto was examined by placing injections of distinct retrograde tracers into different parts of FEF that represented saccades of different amplitudes. Central FEF (lateral area 8A), which represents saccades of intermediate amplitudes, received afferents from a larger portion of SEF than did lateral FEF (area 45), which represents shorter saccades, or medial FEF (medial area 8A), which represents the longest saccades in addition to pinna movements. Moreover, in every case the zone in SEF that innervated lateral FEF (area 45) also projected to medial FEF (area 8A). In one case, a zone in rostral SEF projected to both lateral area 8A from which eye movements were evoked by microstimulation as well as medial area 8A from which pinna movements were elicited by microstimulation. This pattern of afferent convergence and divergence from SEF onto the retinotopic saccade map in FEF is indicative of some sort of map transformation between SEF and FEF. Such a transformation would be necessary to interconnect a topographic craniotopic saccade representation in SEF with a topographic retinotopic saccade representation in FEF.
Characterization of a calcium/calmodulin-dependent protein phosphatase in theLimulusnervous tissue and its light regulation in the lateral eye
Authors: Ellis D. Z. , Edwards S. C. 
Published: June 2009

AbstractCalcium (Ca2+) plays an integral role in the light response of the photoreceptors in both vertebrate and invertebrate organisms. In the ventral eye of the horseshoe crab,Limulus polyphemus, a flash of light delivered to a dark-adapted photoreceptor stimulates a rapid rise in intracellular free calcium concentration ([Ca2+]i), which in turn mediates light adaptation. It has previously been demonstrated that inLimulusphotoreceptors light,viaCa2+, activate s a calcium/calmodulin (Ca2+/CaM)-dependent protein kinase which increases the phosphorylation of arrestin. We now have identifie d biochemically, a calcium/calmodulin-dependent protein phosphatase (Ca2+/CaM PP ) in homogenates of theLimuluslateral and ventral eye, brain, and lateral optic nerve using as a substrate, a32P-labeled peptide fragment of the regulatory subunit of cAMP-dependent protein kinase (RII). This protein phosphatase shares biochemical properties with calcineurin, a Ca2+/CaM-dependent protein phosphatase (type-2B). Its activity is enhanced by Ca2+, calmodulin and Mn2+; and is inhibited by mastoparan, a calmodulin antagonist, and a synthetic peptide corresponding to the autoinhibitory domain of mammalian calcineurin. Most importantly, light regulates the Ca2+/CaM PP activity in the lateral eye. While there is no difference in basal activity in long-term dark- or light-adapted preparations, Ca2+enhances Ca2+/CaM PP activity only in long-term light-adapted eyes.
Vasoactive intestinal polypeptide modulates GABAAreceptor function through activation of cyclic AMP
Authors: Veruki Margaret L. , Yeh Hermes H. 
Published: June 2009

AbstractVasoactive intestinal polypeptide (VIP) has been shown to potentiate current responses elicited by activation of the GABAAreceptor (IGABA) in freshly dissociated ganglion cells of the rat retina. Here we tested the hypothesis that this heteroreceptor cross talk is mediated by an intracellular cascade of events that includes the sequential activation of a stimulatory guanine nucleotide binding (Gs) protein and adenylate cyclase, the subsequent increase in levels of cyclic AMP and, finally, the action of the cyclic AMP-dependent protein kinase (PKA). Intracellular dialysis of freshly dissociated ganglion cells with GTPγsirreversibly potentiatedIGABA, while GDPßseither decreased or had no effect onIGABA. Additionally, GDPßsblocked the potentiation ofIGABAby VIP. Cholera toxin rendered VIP ineffective in potentiatingIGABA, while pertussis toxin had no effect on the VIP-induced potentiation ofIGABA. Extracellular application of either forskolin or 8-bromo-cyclic AMP potentiatedIGABA, as did the introduction of cyclic AMP directly into the intracellular compartment through the recording pipet. Intracellular application of cyclic AMP-dependent protein kinase (PKA) potentiatedIGABA, while a PKA inhibitor blocked the potentiating effect of VIP. These results lead us to conclude that activation of a cyclic AMP-dependent second-messenger system mediates the modulation of GABAAreceptor function by VIP in retinal ganglion cells.
Regulation of endogenous dopamine release in amphibian retina by melatonin: The role of GABA
Authors: Boatright Jeffrey H. , Rubim Nara M. , Iuvone P. Michael 
Published: June 2009

AbstractIn the retina of the African clawed frog (Xenopus laevis), endogenous dopamine release increases in light and decreases in darkness. Exogenous melatonin and several chemical analogs of melatonin suppressed light-evoked dopamine release from frog retina in a concentration-dependent manner. The rank order of potency for inhibition of light-evoked dopamine release was melatonin » 5-methoxytryptamine ≥N-acetylserotonin > 5-methoxytryptophol ⋙ serotonin. Melatonin did not suppress dopamine release below levels seen in darkness. The putative melatonin receptor antagonist luzindole inhibited the effect of melatonin. Luzindole enhanced dopamine release in darkness but had little effect in light. These data suggest a role for endogenous melatonin in dark-induced suppression of retinal dopamine.Picrotoxin and bicuculline, GABA-A receptor antagonists, blocked melatonin-induced suppression of dopamine release. In the presence of melatonin, bicuculline was significantly less potent in stimulating dopamine release. These results suggest that melatonin enhances GABAergic inhibition of light-evoked dopamine release. This mechanism may underlie the light/dark difference in dopamine release in vertebrate retina.