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Results for “Retinal Horizontal Cells”

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PubMed2006

NADPH-diaphorase activity in the superficial layers of the superior colliculus of rats during aging.

Neurons in the superficial layers of the superior colliculus are key elements in the visual system of rodents since they receive extensive afferent projections from retinal ganglion cells. The NADPH-diaphorase histochemical technique was used to detect differences in neuronal nitric oxide synthase (nNOS) in the superficial layers of the superior colliculus (sSC) of young adult (3 months) and aged (24 and 26 months) rats. The orientation of the dendritic processes of NADPH-diaphorase-positive neurons, cross-sectional area, and number of neurons per mm2 were analyzed. NADPH-d histochemistry revealed a high number of NADPH-d-positive cells in the stratum zonale and stratum griseum superficiale in adult and aged animals. NADPH-d-positive neurons were classified into the following morphological types: marginal, horizontal, pyriform, narrow-field vertical, wide-field vertical, and stellate. During aging, narrow field vertical and wide field vertical neurons present somatic atrophy and an increase in dendritic processes with dorsoventral orientation, whereas wide field vertical neurons show a decrease in those with lateromedial orientation. Marginal neurons undergo somatic hypertrophy at 26 months when compared with those at 3 months. The remaining types of neurons do not undergo size changes. Finally, the number of NADPH-d-positive neurons per mm2 in the various types of morphology does not significantly change with age. It is suggested to be likely that the aging process in the nitrergic neurons of the sSC does not lead to significant changes in the synthesis of NO from the constitutive NOS isoforms.

Aging↗

PubMed2000

Stimulus pattern related plasticity of synapses between cones and horizontal cells in carp retina.

Stimulus pattern related synaptic plasticity in the luminosity-type horizontal cell (LHC) of isolated carp retina was investigated. The major findings were: (1) repetitive red flashes progressively strengthened the synaptic connection between red-cone and LHC, whereas weakened that between green-cone and LHC; (2) repetitive green flashes remarkably depressed the LHC's red response, but caused little changes in the cell's green response. A competitive depression between different cone signals is suggested.

Animals↗

PubMed2005

Photoreceptors and visual pigments in the retina of the fully anadromous green sturgeon (Acipenser medirostrus) and the potamodromous pallid sturgeon (Scaphirhynchus albus).

Green sturgeon and pallid sturgeon photoreceptors were studied with scanning electron microscopy (SEM), microspectrophotometry and, in the case of the green sturgeon, retinal whole-mounts. The retinas of both species contain both rods and cones: cones comprise between 23% (whole-mount) and 36% (SEM) of the photoreceptors. The cone population of both species is dominated by large single cones, but a rare small single cone is also present. In both species, most rods have long outer segments of large diameter. A rod with a relatively thin outer segment is present in the pallid sturgeon retina. Mean cone packing density for the entire green sturgeon retina is 4,690+/-891 cones/mm2, with the dorsal retina 14% more dense than the ventral. There is evidence for a horizontal visual streak just above and including the optic disc. Mean rod packing density is 16,006+/-1,668 rods/mm2 for the entire retina, and fairly uniform throughout. Both species have rods with peak absorbance near 540 nm, as well as short-wavelength-sensitive cones (green: 464.5+/-0.7 nm; pallid: 439.7+/-3.5 nm); middle-wavelength-sensitive cones (green: 538.0+/-1.4 nm; pallid: 537.0+/-1.7 nm); and long-wavelength-sensitive cones (green: 613.9+/-3.0 nm; pallid: 617.8+/-7.6 nm).

Animals↗

PubMed2006

Presence of glutamate, glycine, and gamma-aminobutyric acid in the retina of the larval sea lamprey: comparative immunohistochemical study of classical neurotransmitters in larval and postmetamorphic retinas.

The neurochemistry of the retina of the larval and postmetamorphic sea lamprey was studied via immunocytochemistry using antibodies directed against the major candidate neurotransmitters [glutamate, glycine, gamma-aminobutyric acid (GABA), aspartate, dopamine, serotonin] and the neurotransmitter-synthesizing enzyme tyrosine hydroxylase. Immunoreactivity to rod opsin and calretinin was also used to distinguish some retinal cells. Two retinal regions are present in larvae: the central retina, with opsin-immunoreactive photoreceptors, and the lateral retina, which lacks photoreceptors and is mainly neuroblastic. We observed calretinin-immunostained ganglion cells in both retinal regions; immunolabeled bipolar cells were detected in the central retina only. Glutamate immunoreactivity was present in photoreceptors, ganglion cells, and bipolar cells. Faint to moderate glycine immunostaining was observed in photoreceptors and some cells of the ganglion cell/inner plexiform layer. No GABA-immunolabeled perikarya were observed. GABA-immunoreactive centrifugal fibers were present in the central and lateral retina. These centrifugal fibers contacted glutamate-immunostained ganglion cells. No aspartate, serotonin, dopamine, or TH immunoreactivity was observed in larvae, whereas these molecules, as well as GABA, glycine, and glutamate, were detected in neurons of the retina of recently transformed lamprey. Immunoreactivity to GABA was observed in outer horizontal cells, some bipolar cells, and numerous amacrine cells, whereas immunoreactivity to glycine was found in amacrine cells and interplexiform cells. Dopamine and serotonin immunoreactivity was found in scattered amacrine cells. Amacrine and horizontal cells did not express classical neurotransmitters (with the possible exception of glycine) during larval life, so transmitter-expressing cells of the larval retina appear to participate only in the vertical processing pathway.

Animals↗

PubMed2004

Comparative study of cholinergic cells in retinas of various mouse strains.

We examined cholinergic cells in the retinas of BALB/C albino, C57BL/6J black, and 129/SvJ light chinchilla mice by using immunocytochemistry with specific antisera against choline acetyltransferase (ChAT). Two types of ChAT-immunoreactive amacrine cell bodies were found in the inner nuclear layer (INL) and ganglion cell layer in the retinas of all three mouse strains. They were distributed with mirror-image symmetry and their processes ramified in strata 2 and 4 of the inner plexiform layer. A distinct type of ChAT-immunoreactive cell was found only in C57BL/6J mouse retina. The somata of this third type of ChAT-immunoreactive cell were located in the outermost part of the INL, with their processes extending toward the outer plexiform layer. Double-labeling experiments demonstrated that these were not horizontal cells and that they were GABA-immunoreactive. The results suggested that these cells were probably "misplaced" cholinergic amacrine cells showing GABA immunoreactivity. This feature of the C57BL/6J mouse retina should be taken into account in studies of mutant mice having a mixed genetic background with a C57BL/6J contribution.

Amacrine Cells↗

PubMed1986

The optic tectum of gymnotiform teleosts Eigenmannia virescens and Apteronotus leptorhynchus: a Golgi study.

Golgi, Nissl, Bielschowsky and cholinesterase techniques have been used to analyze the optic tectum of the weakly electric teleost fish Eigenmannia virescens and Apteronotus leptorhynchus. Six layers are readily distinguished: a fairly thick stratum marginale, a narrow stratum opticum and stratum fibrosum et griseum superficiale, a well-developed stratum griseum centrale, a stratum album centrale and a compact stratum periventriculare. Fifty-six neuronal types are present. In regard to comparative aspects of tectal organization, it became apparent that although most neuronal types are similar to those reported in other teleostean fish, there are certain obvious differences such as: pyramidal cell somata not confined to stratum fibrosum et griseum superficiale, but also clustered in the adjacent stratum opticum, presenting stratified or diffuse basilar dendritic arbors; and a change from vertical to oblique and almost horizontal neuronal orientation in the ventral and caudal tectum. The presence of pyramidal cells with aligned and misaligned apical and basal dendritic fields. A cell of stratum griseum centrale with an ascending axon to stratum opticum. A special projection type of fusiform cell of stratum griseum centrale, with an efferent axon of somatic origin. A cell rich stratum griseum centrale, with a wider variety of multipolar and bipolar cell population than reported in other teleosts. Fourteen types of pyriform cells are present, four of which are efferent. Our observations are suggestive of regional differences in regard to the caudalmost tectum in Apteronotus: presumably this is related to the extremely sparse retinal input to this part of the tectum. A close functional correlation has been found between some multipolar and pyriform cells identified in our material with similar cells reported by Rose and Heiligenberg as multisensory cells, following recordings and horseradish peroxidase fillings of these cells. Based on the observation of patchy torus semicircularis input to stratum fibrosum et griseum superficiale, disjunct from the retinal input to this layer, it is proposed that perhaps this arrangement is the result of competition for synaptic targets during development.

Animals↗

PubMed2003

Spatial summation of S-cone ON and OFF signals: effects of retinal eccentricity.

We studied spatial summation for S-cone ON and OFF signals as a function of retinal eccentricity in human subjects. S-cone isolation was obtained by the two-colour threshold method of Stiles, modified by adding blue light to the yellow background. Test stimuli were blue light increments or decrements within a circular area of variable size. These were presented for 100 ms at 0 to 20 deg along the horizontal temporal retinal meridian. Ricco's area of complete spatial summation was measured from the threshold vs. area curves. This was nearly constant and approximately the same for both types of stimuli within the 0-5 deg range and increased beyond this range. The decremental area increased faster, suggesting that separate mechanisms, presumably ON and OFF, integrate S-cone increments and decrements. The results appear to provide new evidence for the existence of separate S-cone ON and OFF pathways. We compare the data with known morphology of primate retina and assume that, if S-cone decrements are detected via separate OFF cells, these should differ in density and dendritic field size from the S-cone ON cells, but only in the retinal periphery.

Adult↗

PubMed1980

Central and peripheral retinal photoreceptor orientation in amblyopic eyes as assessed by the psychophysical Stiles-Crawford function.

Retinal photoreceptor orientational tendencies were assessed within both eyes of samples of control and selected functional amblyopic observers, with the psychophysical Stiles-Crawford (S-C) function used as an indicator. S-C function determinations were made at testing locations spanning 30 degrees of the horizontal meridian of the visual field and including the forced region. Normal-appearing S-C functions with peak locations which clustered within a subregion of the pupil were found for all but one of the eyes tested. The single exception was a non-amblyopic eye of one of the amblyopic observers. Thus, within this sample of amblyopic eyes, visual acuity deficits are apparently not related to retinal photoreceptor alignment anomalies.

Amblyopia↗

PubMed1986

Laminar organization of ON and OFF regions and ocular dominance in the striate cortex of the tree shrew (Tupaia belangeri).

The organization of ON and OFF responses and ocular dominance in the striate cortex of the tree shrew was electrophysiologically investigated by using flashed, stationary visual stimuli presented monocularly to either the ipsilateral or contralateral eye. We measured cortical multi-unit activity at 25-micron intervals with glass-insulated platinum-plated tungsten microelectrodes. Penetrations were made perpendicular to the cortical layers and the responses were quantitatively analyzed in layers IIIc to V. In sublayers IIIb, IIIc, and upper V, phasic responses of approximately equal magnitude occurred to both light ON and light OFF (ON-OFF regions). In layer IV, tonic as well as phasic responses were often evoked by the flashed spot of light. In sublayer IVa stronger responses occurred to light ON than to light OFF (ON region) while in sublayer IVb stronger responses occurred to light OFF than to light ON (OFF region). In an ON region, the increased neural activity that occurred at light ON was often accompanied by a decrease in activity below baseline level at light OFF. A similar decrease often occurred in an OFF region at light ON. Recordings from the region of the cell-sparse cleft in layer IV were characterized by ON-OFF responses, signalling a transition zone between sublayers IVa and IVb. In addition, the responses to stimulation of the ipsilateral eye typically were very weak in the cleft region. In the other regions examined, the multi-unit activity generally was driven binocularly with slightly greater responses being elicited by the contralateral eye. We conclude that the ON-center and OFF-center afferent pathways that are organized at the retinal level remain generally segregated in the tree shrew through the first synapse in the striate cortex. In addition, our recordings confirm that a horizontal organization of ocular dominance occurs in layer IV of the striate cortex in tree shrews.

Animals↗

PubMed1989

Glutamatergic separation of ON and OFF retinal channels: possible modulation by glycine and acetylcholine.

When intravitreally injected into the frog in vivo, 2-amino-4-phosphonobutyrate (APB) and cis-2,3-piperidine dicarboxylic acid (PDA) showed opposite effects on ON and OFF retinal channels: APB abolished the ON responses in the electroretinogram and in ganglion cell activity, and increased OFF responses. At the same time the receptive field area was enlarged, and the inhibition exerted by the surround was suppressed. A cholinergic/glycinergic loop involving amacrine cells was suggested to be the pathway of the inhibitory ON input upon the OFF channel. PDA abolished the OFF responses in the ERG and in ganglion cell activity, while increasing the ON response in the ERG and decreasing the ganglion cell sensitivity at ON. The receptive field area was not modified, but the inhibition exerted by the surround was suppressed, probably by a blockade of horizontal cell glutamate receptors.

Acetylcholine↗

PubMed1997

A quantitative study of ganglion cells in the goat retina.

As in a number of mammals, the most prominent feature of the ganglion-cell layer in the retina of the murciano-granadina goat is an increase in the density of ganglion cells in the central area, as well as a concentration along a ridge extending horizontally across the retina, below the optic disc, and in the upper temporal retina. Thus, there is an area of maximum density and two streaks that are known as the 'horizontal' and 'vertical' streak. The isodensity lines of ganglion-cell distribution is toughly concentric, with their values varying from 304 cells/mm2 in the periphery to 3592 cells/mm2 in the central area, with the cells densely packed. There were some individual differences amongst the animal studied, although all of them were purebred animals.

Animals↗

PubMed2000

Binocular summation in the fovea and peripheral field of anisometropic amblyopes.

PURPOSE: Binocular performance in the central and peripheral visual fields was compared for normal and anisometropic amblyopes. METHODS: Binocular and monocular thresholds to a light detection task were measured along the four principal meridia in 10 young normal subjects and 10 anisometropic amblyopes using the Humphrey's Visual Field Analyser. Thresholds were obtained at the fovea and at retinal eccentricities of 5 masculine, 10 masculine, 15 masculine, 25 masculine, 40 masculine and 55 masculine on the horizontal, vertical and oblique meridia of 45 masculine and 135 masculine. RESULTS: Binocular summation ratios (binocular sensitivity/ 'best' monocular sensitivity) were calculated for all the eccentricities. In the normal group, the mean binocular summation ratio for the fovea and the peripheral field was not significantly different. In the amblyopic group, subjects showed no or minimal binocular summation in the foveal region but reached normal ratios in the periphery. DISCUSSION: Results are discussed in terms of tolerance to interocular sensitivity differences in the periphery and selective losses in cortical cells.

Adolescent↗

PubMed2001

An analysis of the dependence of saccadic latency on target position and target characteristics in human subjects.

BACKGROUND: Predictions from conduction velocity data for primate retinal ganglion cell axons indicate that the conduction time to the lateral geniculate nucleus for stimulation of peripheral retina should be no longer than for stimulation of central retina. On this basis, the latency of saccadic eye movements should not increase for more peripherally located targets. However, previous studies have reported relatively very large increases, which has the implication of a very considerable increase in central processing time for the saccade-generating system. RESULTS: In order to resolve this paradox, we have undertaken an extended series of experiments in which saccadic eye movements were recorded by electro-oculography in response to targets presented in the horizontal meridian in normal young subjects. For stationary or moving targets of either normal beam intensity or reduced red intensity, with the direction of gaze either straight ahead with respect to the head or directed eccentrically, the saccadic latency was shown to remain invariant with respect to a wide range of target angular displacements. CONCLUSIONS: These results indicate that, irrespective of the angular displacement of the target, the direction of gaze or the target intensity, the saccade-generating system operates with a constant generation time.

Adult↗

PubMed1979

[Dendroarchitectonic study of the neurons of the corpus quadrigeminum superius in man].

Two different functional zones may be described in the superior colliculus. The superficial layers receive retinal and cortical fibers, the deep layers are a multimodal center and are implied in the oculo-motor control mechanisms. The aim of the present study has been to use network analysis in order to quantify the cell types of the deep layers of the superior colliculus in Man. 50 Golgi impregnated cell have been drawn in the three plans of space. Topological analysis permits to emphasize the existence of two different cell types: collaterally-branched cells or CB cells, and dichotomously-branched cells or DR cells. Quantitative analysis of the dendritic arcs has shown the spatial orientation of the dendritic tree. The proximal dendrites of DR cells are in the horizontal plane, the terminal dendrites are in the vertico-frontal plane. This difference seems to be due to different functional afferences.

Aged↗

PubMed2006

Effects of follistatin overexpression on cell differentiation in the chick embryo retina.

Although activin is expressed in the embryonic central nervous system (CNS), its possible functions in the regulation of CNS neuronal differentiation remain largely unknown. We have investigated this question in the retina, a well-characterized CNS structure previously shown to respond to activin in vitro, and to express activin subunits and receptors in vivo. RCAS retroviruses were used to overexpress in the chick retina in ovo either follistatin (FS), an activin-binding protein and inhibitor, or alkaline phosphatase (AP), as control. FS-treated retinas appeared normal until ED 8, when they showed a reduction of the inner plexiform layer, accompanied by a marked decrease in the frequency of amacrine cells. The territory lacking amacrine cells showed downregulation of transcription factors necessary for amacrine cell differentiation, such as Pax6 and AP2alpha, accompanied by ectopic expression of transcription factors associated with the development of horizontal or bipolar neurons, such as Prox1, Chx10 and NeuroM. Increases in cell death were also observed in FS-treated retinas. Taken together with previous in vitro studies, our results suggest that activin is a powerful regulator of neuronal differentiation in the central nervous system.

Activins↗

PubMed1994

'Unilateral cone dystrophy': ERG changes implicate abnormal signaling by hyperpolarizing bipolar and/or horizontal cells.

The two cases described here appear to represent the infrequently reported entity of "unilateral cone (cone-rod) dystrophy." Both cases give the suggestion that daylight vision can be affected by abnormalities in visual signals in the proximal retina, after they leave the cone photoreceptors themselves. The ERG waveform changes in these two cases are consistent with a deficit in signaling by the hyperpolarizing bipolar cells, and the complaint of abnormal color perception in both cases presented here raises the possibility that the OFF-pathway through hyperpolarizing bipolar cells may be important for color processing.

Aged↗

PubMedDate not supplied

GABA and GAD immunoreactivity of photoreceptor terminals in primate retina.

Within the vertebrate retina, two types of photoreceptor cells--the rods and cones--transduce visual signals and convey this information through synapses with bipolar and horizontal cells. Although the neurotransmitter at these first-order synapses has not been identified, electrophysiological studies suggest that it might be excitatory. In the present study, however, we have found photoreceptor terminals in the rhesus monkey retina which are immunoreactive with antibodies to either gamma-aminobutyric acid (GABA) or L-glutamic acid decarboxylase (GAD, an enzyme involved in the synthesis of GABA). In the perifoveal region of the retina, approximately 25% of presynaptic profiles having ultrastructural characteristics of either rod or cone terminals are immunoreactive with one or the other antibody. This evidence for a putatively inhibitory neurotransmitter in photoreceptor terminals challenges present understanding of retinal synaptic function.

Animals↗

PubMedDate not supplied

Changes in pattern electroretinograms to equiluminant red-green and blue-yellow gratings in patients with early Parkinson's disease.

In Parkinson's disease (PD), the luminance pattern electroretinogram (PERG) is reported to be abnormal, indicating dysfunction of retinal ganglion cells (RGCs). To determine the vulnerability of different subpopulations of RGCs in PD patients, the authors recorded the PERG to stimuli of chromatic (red-green [R-G] and blue-yellow [B-Y]) and achromatic (yellow-black [Y-Bk]) contrast, known to emphasize the contribution of parvocellular, koniocellular, and magnocellular RGCs, respectively. Subjects were early PD patients (n = 12; mean age, 60.1 +/- 8.3 years; range, 46 to 74 years) not undergoing treatment with levodopa and age-sex-matched controls (n = 12). Pattern electroretinograms were recorded monocularly in response to equiluminant R-G, B-Y, and Y-Bk horizontal gratings of 0.3 c/deg and 90% contrast, reversed at 1Hz, and presented at a viewing distance of 24 cm (59.2 x 59 degree field). In PD patients, the PERG amplitude was significantly reduced (by 40 to 50% on average) for both chromatic and luminance stimuli. Pattern electroretinogram latency was significantly delayed (by about 15 ms) for B-Y stimuli only. Data indicate that, in addition to achromatic PERGs, chromatic PERGs are altered in PD before levodopa therapy. Overall, chromatic PERGs to B-Y equiluminant stimuli exhibited the largest changes. Data are consistent with previous findings in PD, showing that visual evoked potentials (VEP) to B-Y chromatic stimuli are more delayed than VEPs to R-G and achromatic stimuli. The results suggest that the koniocellular subpopulation of RGCs may be particularly vulnerable in early stages of Parkinson's disease.

Aged↗