Horizontal Cell Receptive Field Research Articles

The receptive field construction of midget ganglion cells in primate retina.

The midget pathway of the primate retina provides the visual system with the foundations for high spatial resolution and color perception. An essential contributor to these properties is center-surround organization, in which responses from the central area of a cell's receptive field are antagonized by responses from a surrounding area. Two key questions about center-surround organization are unresolved. First, the surround is largely or completely due to negative feedback from horizontal cells to cones: how can this feedback be reconciled with the popular difference of Gaussians (DOG) model, which implies feedforward inhibition? Second, can the spatial extent of center and surround be predicted from the components-optics, horizontal cell receptive field, ganglion cell dendrites-that give rise to them? We address these questions with a computational model of midget pathway signal processing in macaque retina; model parameters are derived from published literature. We show that, contrary to the DOG model, the surround's effect is better treated as divisive. A simplified version of our model-a ratio of Gaussians (ROG) model-has practical advantages over the DOG, such as accounting for spatiotemporal interactions and pulse responses. The ROG model also shows that both center and surround radii can be calculated from a sum of squared radii of their components. Finally, chromatic antagonism between center and surround in the full model predicts cone opponency as a function of eccentricity. We suggest that a signal-processing model gives new insight into retinal function.NEW & NOTEWORTHY We simulated signal processing from cones to midget ganglion cells in the monkey retina and found that: 1) center/surround structure is better described as a ratio of Gaussian functions than as the traditional difference of Gaussians; 2) ganglion cell center and surround radii can be calculated from a sum of squares of radii in upstream stages; 3) the model can predict chromatic dominance in the center and surround mechanisms as a function of eccentricity.

Realistic Mathematical Model of Retinal Outer Plexiform Layer for Edge Detection.

Edge information is essential for object recognition and motion detection. It is reported that photoreceptors, horizontal cells and bipolar cells in the outer retina involved for edge detection. Moreover, it is known that the center and the surround receptive field structure found in the bipolar cell layer is thought to be related to an initial process of edge detection. In the present study, we constructed retinal network models including photoreceptors, horizontal cells, and bipolar cells using single-compartment neurons to investigate those contributions for edge detection. We simulate fixation of a natural image with changing the size of the horizontal cell receptive field and confirmed that the constructed model successfully extracts edges in the image. Furthermore, most of the edge in the scene is extracted when the size of the horizontal cell receptive field matched with that reported in anatomical evidence. To evaluate the performance of edge detection, we compare the result of edge detection with the Canny algorithm. As a result, we conformed that the model well detects fine edges similar to the Canny edge detection.

The light-induced reduction of horizontal cell receptive field size in the goldfish retina involves nitric oxide

Horizontal cells of the vertebrate retina have large receptive fields as a result of extensive gap junction coupling. Increased ambient illumination reduces horizontal cell receptive field size. Using the isolated goldfish retina, we have assessed the contribution of nitric oxide to the light-dependent reduction of horizontal cell receptive field size. Horizontal cell receptive field size was assessed by comparing the responses to centered spot and annulus stimuli and from the responses to translated slit stimuli. A period of steady illumination decreased the receptive field size of horizontal cells, as did treatment with the nitric oxide donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (100 μM). Blocking the endogenous production of nitric oxide with the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester (1 mM), decreased the light-induced reduction of horizontal cell receptive field size. These findings suggest that nitric oxide is involved in light-induced reduction of horizontal cell receptive field size.

Horizontal cell receptive fields are reduced in connexin57‐deficient mice

Horizontal cells are coupled by gap junctions; the extensive coupling of the horizontal cells is reflected in their large receptive fields, which extend far beyond the dendritic arbor of the individual cell. In the mouse retina, horizontal cells express connexin57 (Cx57). Tracer coupling of horizontal cells is impaired in Cx57-deficient mice, which suggests that the receptive fields of Cx57-deficient horizontal cells might be similarly reduced. To test this hypothesis we measured the receptive fields of horizontal cells from wildtype and Cx57-deficient mice. First, we examined the synaptic connections between horizontal cells and photoreceptors: no major morphological alterations were found. Moreover, horizontal cell spacing and dendritic field size were unaffected by Cx57 deletion. We used intracellular recordings to characterize horizontal cell receptive fields. Length constants were computed for each cell using the cell's responses to concentric light spots of increasing diameter. The length constant was dependent on the intensity of the stimulus: increasing stimulus intensity reduced the length constant. Deletion of Cx57 significantly reduced horizontal cell receptive field size. Dark resting potentials were strongly depolarized and response amplitudes reduced in Cx57-deficient horizontal cells compared to the wildtype, suggesting an altered input resistance. This was confirmed by patch-clamp recordings from dissociated horizontal cells; mean input resistance of Cx57-deficient horizontal cells was 27% lower than that of wildtype cells. These data thus provide the first quantification of mouse horizontal cell receptive field size and confirm the unique role of Cx57 in horizontal cell coupling and physiology.

Retinoic acid has light-adaptive effects on horizontal cells in the retina.

Ambient light conditions affect the morphology of synaptic elements within the cone pedicle and modulate the spatial properties of the horizontal cell receptive field. We describe here that the effects of retinoic acid on these properties are similar to those of light adaptation. Intraorbital injection of retinoic acid into eyes of dark-adapted carp that subsequently were kept in complete darkness results in the formation of numerous spinules at the terminal dendrites of horizontal cells, a typical feature of light-adapted retinae. The formation of these spinules during light adaptation is impaired in the presence of citral, a competitive inhibitor of the dehydrogenase responsible for the generation of retinoic acid in vivo. Intracellularly recorded responses of horizontal cells from dark-adapted eyecup preparations superfused with retinoic acid reveal typical light-adapted spatial properties. Retinoic acid thus appears to act as a light-signaling modulator. Its activity appears not to be at the transcriptional level because its action was not blocked by actinomycin.

Modulation of horizontal cell receptive fields in the light adapted goldfish retina

In the isolated goldfish retina, 700 nm background illumination increases the horizontal cell receptive field size, as measured with 565 nm slits of light, but decreases the receptive field size, when measured with 660 nm slits. These background-induced changes in receptive field size are absent when the depolarizing responses in bi- and triphasic horizontal cells are blocked by lowering the [Ca2+] in the Ringer's solution from 1.0 to 0.1 mM. These results cannot be explained by the linear properties of the horizontal cell layers, nor by slow adaptational processes, but are consistent with the concept that feedback from horizontal cells to cones modifies the horizontal cell receptive field properties.

The Size of the horizontal cell receptive fields adapts to the stimulus in the light adapted goldfish retina

In this study the dynamic properties of goldfish horizontal cell (HC) receptive fields were evaluated. The size of HC receptive fields increases up to about 60 msec after stimulus onset, and then reduces to a smaller end value. They can therefore not adequately be described by the cable equation. Estimates of the length constant of the HC network based on the sustained responses are about 43% smaller than those based on the initial part of the response. This difference can be accounted for by feedback connections from HCs to cones because negative feedback reduces the receptive field size. The implication is that HCs are strongly coupled when the retina is stimulated more or less homogeneously but that they partly uncouple from the rest of the HC network when they are stimulated differently than the rest of the retina. The HCs thus generate a feedback signal based on the "local" stimulus properties. The size of the HC receptive fields depends on the spatial detail of the stimulus.

P-G2-08 Modulating the dynamics of the horizontal cell receptive fields: M. Kamermans, J. Haak, J. Verweij Lab Medical Physics, University of Amsterdam; The Netherlands Ophthalmic Research Institute

P-G2-08 Modulating the dynamics of the horizontal cell receptive fields: M. Kamermans, J. Haak, J. Verweij Lab Medical Physics, University of Amsterdam; The Netherlands Ophthalmic Research Institute

Modulation of synaptic transfer between retinal cones and horizontal cells by spatial contrast.

We studied the influence of steady annular light on the kinetics and sensitivity of horizontal cell (HC) responses to modulation of the intensity of small concentric spots in the turtle retina. As shown by previous investigators, when the intensity of the annulus was equal to the mean spot intensity, spot response kinetics were the same as those for the modulation of spatially uniform light. Turning off the annulus attenuated dramatically high-frequency flicker sensitivity and enhanced somewhat low-frequency sensitivity. This phenomenon reflects a modulation of synaptic transfer between cones and second-order neurons that is mediated by cones, and it will be referred to as cone-mediated surround enhancement (CMSE). Our main results are as follows: (a) The change in test-spot response sensitivity and kinetics upon dimming a steady surrounding annulus is a consequence of the change in spatial contrast rather than change in overall light level. (b) Introduction of moderate contrast between the mean spot intensity and steady surrounding light intensity causes a marked change in spot response kinetics. (c) The dependence of spot response kinetics on surrounding light can be described by a phenomenological model in which the steady state gain and the time constant of one or two single-stage, low-pass filters increase with decreasing annular light intensity (d) The effect of surrounding light on spot responses of a given HC is not determined by change in the steady component of the membrane potential of that cell. (e) Light outside the receptive field of an HC can affect that cell's spot response kinetics. (f) In an expanding annulus experiment, the distance over which steady annular light affects spot response kinetics varies among HCs and can be quite different even between two cells with closely matched receptive field sizes. (g) The degree of CMSE is correlated with HC receptive field size. This correlation suggests that part of the enhancement mechanism is located in the HC. Taken together, our results suggest the involvement of the inner retina in CMSE.

Spatial organization of the bipolar cell's receptive field in the retina of the tiger salamander.

1. The spatial properties of rods, horizontal cells and bipolar cells were studied by intracellular recording in the isolated, perfused retina of the tiger salamander, Ambystoma tigrinum. Low stimulus intensities were used in order to keep cell responses close to, or within, their linear intensity/response range. 2. Spatial properties of bipolar cell receptive fields, measured while perfusing with normal Ringer solution, were compared with those measured during exposure to agents that eliminated the bipolar cells' receptive field surround (RFS). In this way, the spatial properties of the receptive field centre (RFC) and those of the RFS could be characterized independently. 3. To a good approximation, the contribution to the horizontal cell's response of unit area of its receptive field declined exponentially with distance from the centre of the receptive field. The (apparent) length constant describing this decay was 200 microns. The one-dimensional length constant of the horizontal cell syncytium was thus 248 microns. The variation of response amplitude with the radius of a centred circular stimulus was consistent with this finding. 4. This was true also of the RFCs of bipolar cells. The one-dimensional length constant of the RFC of off-centre bipolar cells averaged 124 microns. That of the RFC of on-centre cells averaged 62 microns though values were more variable, the RFCs of some on-centre cells being comparable to those of off-centre cells. These values were independent of the class of photoreceptor driving the bipolar cell. 5. The large size of the RFCs of off-centre cells and many on-centre cells cannot by explained by light scatter within the retina or by voltage spread within the rod syncytium. We proposed that off-centre cells are tightly coupled in a syncytium. On-centre cells, on average, are less tightly coupled. 6. The spatial properties of the bipolar cell's RFS were consistent with the notion that the RFS represents a convolution of the horizontal cell's receptive field and the bipolar cell's RFC. 7. The spatial properties of bipolar cell receptive fields were reconstructed from the measured properties of their RFCs and the measured properties of horizontal cell receptive fields. Under the conditions of our experiments, the bipolar cell's response could be described by a linear difference between a component generated by the RFC and a component generated by the RFS. 8. The spatial filtering characteristics of the bipolar cells were calculated from our data.(ABSTRACT TRUNCATED AT 400 WORDS)

The actions of gamma-aminobutyric acid, glycine and their antagonists upon horizontal cells of the Xenopus retina.

We examined the effects of gamma-aminobutyric acid (GABA) and glycine and their respective antagonists, picrotoxin and strychnine, upon the membrane potential and light-evoked responses of the type H1 horizontal cell of the Xenopus retina. This horizontal cell receives mixed input from rod and cone receptors. Under control conditions the mean membrane potential was -37.8 +/- 9.7 mV. Addition of 5 mM-GABA to the superfusate hyperpolarized the cell by 4.0 +/- 2.6 mV within 3-5 min; addition of 0.5 mM-picrotoxin depolarized the cell by 4.3 +/- 2.1 mV. Prolonged (greater than 15 min) exposures to the drugs elicited more pronounced changes in membrane potential. GABA and picrotoxin affected primarily the cone-dependent input to the H1 horizontal cell. Under dark-adapted conditions, response wave forms were essentially unaltered by the drugs, but when the horizontal cell was moderately or fully light adapted, GABA reduced and picrotoxin enhanced the cone-dependent component of its response to light. Long-term (greater than 15 min) exposures to GABA and picrotoxin elicited changes in response kinetics usually associated with dark and light adaptation, respectively. Glycine, at bath concentrations of 0.6 mM or greater, depolarized horizontal cells by 21 mV on average and reduced or abolished their light response. This action did not occur in the presence of 0.1 mM-strychnine. When all light-evoked activity was blocked by 20-40 mM-magnesium, the depolarizing action of glycine still occurred. Thus, glycine appears to act directly upon the horizontal cell membrane. Neither GABA nor glycine, nor their respective antagonists, affected the spatial extent of the horizontal cell receptive field.

Spatiotemporal Nonlinear Analysis of Frog Horizontal Cells

Abstract The shapes of horizontal cell receptive fields in the frog retina were determined using a retinotopic mapping technique based on a 16 X 16 spatial array of stimuli. Fields derived from first order kernel magnitude were sometimes circular but more often elliptical. Morphologic studies of Golgi stained horizontal cells showed most to be elliptical with a non random orientation tending to orthogonality. It is suggested that this feature makes unlikely an explanation of field eccentricity based on cell alignment. It is noted that cell axons tend to cross the retina in a line and may function as an extended dendrite to provide the eccentric and elliptical receptive fields.