Processing of Color- and Noncolor-Coded Signals in the Gourami Retina. I. Horizontal Cells

1997 ◽  
Vol 78 (4) ◽  
pp. 2002-2017 ◽  
Author(s):  
Hiroko M. Sakai ◽  
Hildred Machuca ◽  
Ken-Ichi Naka

Sakai, Hiroko M., Hildred Machuca, and Ken-Ichi Naka. Processing of color- and noncolor-coded signals in the gourami retina. I. Horizontal cells. J. Neurophysiol. 78: 2002–2017, 1997. There are two types of horizontal cells, the luminosity and the chromaticity cells, in the retina of the kissing gourami, Helostoma rudolfi. Luminosity cells occupy the outermost layer proximal to the receptor terminals, whereas chromaticity cells form a layer proximal to the layer of luminosity cells. Neither type of cell has axons. Responses were evoked by light from red and green light-emitting diodes. The two stimuli were modulated either by a pulsatile or a white-noise signal. The luminosity cell always produced a hyperpolarizing response. The chromaticity cell produced a hyperpolarizing response when stimulated by only one color. However, in the presence of a steady or modulated green input, a red stimulus produced a depolarizing response. Such chromaticity cells were similar to the (spectral) biphasic chromaticity horizontal cells observed in other retinae. The depolarizing phase of the red response was produced by the balance of intensity of the two inputs, red and green. We used white-noise methodology to identify the dynamics of the horizontal cell's modulation response by taking advantage of the fact that a Wiener kernel is a measure of a cell's incremental sensitivity, which includes its response dynamics. Under all conditions, a steady state modulation response by both luminosity and chromaticity cells always was related linearly to the input modulation. The average mean square error (MSE) of the model predicted by the first-order kernel was ∼8% for both luminosity ( n = 116) and chromaticity ( n = 23) cells. In some cases, the MSE was a few percent even when the peak-to-peak response amplitude was nearly 30 mV. The ratio of inputs from red and green cones to both types of horizontal cells was variable; the major input for luminosity cells came from red cones, whereas the major input for chromaticity cells came from green cones. First-order kernels generated by the major input were robust in terms of waveform in the sense that the waveform remained unchanged whether or not there was a steady or modulated illumination by the opposing color. The results reported here do not address the question of the neural circuitry that generates horizontal cell responses, in particular, the depolarizing response. However, whatever that circuitry might be, the high degree of linearity of the modulation response by both types of cell under various stimulus conditions imposes restrictions on the performance of any proposed model as well as on mechanisms that underlie the generation of the horizontal cell response.

1994 ◽  
Vol 103 (6) ◽  
pp. 991-1017 ◽  
Author(s):  
S L Stone

The dynamics of color-coded signal transmission in the light-adapted Xenopus retina were studied by a combination of white noise (Wiener) analysis and simultaneous recordings from two types of horizontal cells: chromatic-type horizontal cells (C-HCs) are hyperpolarized by blue light and depolarized by red light, whereas luminosity-type horizontal cells (L-HCs) are hyperpolarized by all wave-lengths. The retina was stimulated by two superimposed fields of red and blue light modulated by two independent white noise signals, and the resulting intracellular responses were decomposed into red and blue components (first-order kernels). The first-order kernels predict the intracellular responses with a small degree of error (3.5-9.5% in terms of mean square error) under conditions where modulated responses exceeded 30 mV in amplitude peak-to-peak, thus demonstrating that both red and blue modulation responses are linear. Moreover, there is little or no interaction between the red- and blue-evoked responses; i.e., nearly identical first-order kernels were obtained for one color whether the other color was modulated or not. In C-HCs (but not L-HCs), there were consistent differences in the dynamics of the red and blue responses. In the C-HC, the cutoff frequency of the red response was higher than for the blue (approximately 12 vs 5 Hz), and the red kernel was more bandpass than the blue. In the L-HC, kernel waveform and cutoff frequencies were similar for both colors (approximately 12 Hz or greater), and the time-to-peak of the L-HC kernel was always shorter than either the red or blue C-HC kernel. These results have implications for the mechanisms underlying color coding in the distal retina, and they further suggest that nonlinear phenomena, such as voltage-dependent conductances in HCs, do not contribute to the generation of modulation responses under the experimental conditions used here.


1982 ◽  
Vol 79 (1) ◽  
pp. 131-145 ◽  
Author(s):  
J Toyoda ◽  
T Kujiraoka

Simultaneous intracellular recordings were made from a bipolar cell and a horizontal cell in the carp retina. The properties of the bipolar cell were studied while injecting current into the horizontal cell. Hyperpolarization of horizontal cells, irrespective of their type, elicited a hyperpolarizing response in on-center bipolar cells and a depolarizing response in off-center bipolar cells. Analyses of the ionic mechanisms of bipolar cell responses revealed that depolarization of horizontal cells simulated and hyperpolarization opposed the effect of central illumination. The effect of polarization was exerted in such a manner that each type of horizontal cells modified the transmission from those photoreceptors from which they receive main inputs. In on-center bipolar cells, for example, the L-type horizontal cells receiving inputs mainly from red cones modified the cone-bipolar transmission accompanied by a conductance change of K+ and/or Cl- channels, and the intermediate horizontal cells receiving inputs from rods modified the rod-bipolar transmission accompanied by a conductance change of Na+ channels. In off-center bipolar cells, the effect of polarization of any type of horizontal cells was mediated mainly by conductance changes of Na+ channels. Feedback mechanisms from horizontal cells to photoreceptors could explain these results reasonably well.


1979 ◽  
Vol 42 (2) ◽  
pp. 441-454 ◽  
Author(s):  
K. I. Naka ◽  
R. Y. Chan ◽  
S. Yasui

1. We define absolute sensitivity as (voltage/illuminance) and incremental sensitivity as the peak-to-peak amplitude of the first-order (Wiener) kernels. 2. Incremental sensitivity of the horizontal cells is the local slopes of the Michaelis-Menten equation and that of more proximal neurons is the Fechner slope. In a log-log plot, the former has a slope of -2, whereas the latter a slope of -1, as predicted by Williams and Gale (39). 3. During a moderate to strong steady illumination, absolute sensitivity decreases but incremental sensitivity increases. The reverse occurs during dark adaptation. 4. The presence of a steady illumination did not prevent signal transmission from horizontal to ganglion cells. 5. From these results we conclude that: adaptation in the catfish retina includes two components: a) a lateral shift of the voltage-intensity curve along the intensity axis, and b) changes in the time course of light-evoked response. We argue that the latter phenomenon is related to the presumed horizontal cell-to-receptor cell negative feedback.


1987 ◽  
Vol 58 (6) ◽  
pp. 1329-1350 ◽  
Author(s):  
H. M. Sakai ◽  
K. Naka

1. We analyzed the light-evoked responses of retinal neurons by means of a white-noise technique. Horizontal and bipolar cells produced a modulation response that was linearly related to a modulation of the mean luminance of a large field of light. The first-order kernels were capable of reproducing the cells' modulation response with a fair degree of accuracy. The amplitude as well as the waveform of the kernels changed with the change in the mean luminance. This is a parametric change and is a form of field adaptation. As the time constant of the parametric change was much longer than that of the modulation response (memory), neurons were assumed to be at a dynamic steady state at a given mean luminance. 2. With the presence of a steady annular illumination, the first-order kernel derived from stimulation with a small spot of light became faster in peak response time and larger in amplitude. For horizontal-cell somas and bipolar cells, the surround also linearized their modulation response. This surround enhancement has been seen in all the cone-driven retinal cells except the receptor and horizontal cell axon, in which a steady surround decreased the amplitude of the spot-evoked kernel but shortened the peak response time. 3. A change in the modulation depth did not affect either the amplitude or the wave-form of the first-order kernels from the horizontal and bipolar cells. In the amacrine and ganglion cells, on the other hand, the amplitude of kernels was related inversely to the depth of modulation. These cells were more sensitive to the modulation of a small modulation depth. 4. A static nonlinearity appeared when signals were transmitted to the amacrine cells. The nonlinearity was first produced in the type-C amacrine cells by a process, which could be modeled by squaring the bipolar cell response. A gamut of more complex second-order nonlinearities found in type-N amacrine cells could be modeled by a band-pass filtering of the type-C cell response. Linear components in the bipolar cells and nonlinear components in the amacrine cells are encoded into spike trains in the ganglion cells. Thus, under our simple stimulus regimen, the ganglion cells transformed the results of the preganglionic signal processing into a spike train without much modification. 5. We propose a tentative diagram of the signal flow in the cone-driven catfish retinal neurons based on this and previous studies.(ABSTRACT TRUNCATED AT 400 WORDS)


2006 ◽  
Vol 23 (3-4) ◽  
pp. 437-440 ◽  
Author(s):  
MARLISON JOSÉ L. DE AGUIAR ◽  
DORA FIX VENTURA ◽  
MANOEL DA SILVA FILHO ◽  
JOHN MANUEL DE SOUZA ◽  
ROGÉRIO MACIEL ◽  
...  

The objective of the present work was to determine the interaction of cone inputs in the response of horizontal cells using heterochromatic flicker photometry (HFP). Intracellular electrophysiological recordings were made in horizontal cells of isolated retinae of carp maintained in physiological solution, with the receptor side up. Sharp glass microelectrodes filled with 3 M KCl solution with resistances between 100 and 120 MΩ were used. Stimuli comprised six cycles of two 6-Hz sinusoidal light waves in counterphase adjusted for the same number of quanta: a green light (550 nm) from a monochromator with a Xenon lamp and an LED red light (628 nm). The stimulation program consisted of 10 steps with the 550-nm wave at constant amplitude, while the 628-nm wave varied in increments of 10% up to 100%, followed by another 10 steps with the 628-nm wave at constant amplitude while the 550-nm wave varied in increments of 10% up to 100%. We recorded responses from four different horizontal cell classes: H1 (monophasic, broadband, n = 37), H2 (biphasic, red-green color-opponent, n = 13), and H3 (biphasic, blue-yellow color-opponent, n = 2) cone horizontal cells; and RH (monophasic, broadband, n = 3) rod horizontal cells. H1 and RH horizontal cells showed a similar cancellation point at a heterochromatic mixture consistent with mixed inputs from 630- and 550-nm cones. No cancellation point was found for the H2 cell class. Fish H1 cells add cone inputs and signal “luminance” in light levels appropriate for cone stimulation. The same occurs with RH cells, which also signal “luminance,” but in light levels appropriate for rod work. For both cell classes there is an HFP cancellation point occurring at a combination of 628-nm and 550-nm lights in opposing phase that leads to the cancellation of the cell's response. No cancellation was found for H2 and H3 cells, which are the chromatically opponent horizontal cells in lower vertebrates.


1987 ◽  
Vol 89 (2) ◽  
pp. 321-337 ◽  
Author(s):  
K I Naka ◽  
M A Itoh ◽  
R L Chappell

The response dynamics of turtle photoreceptors (cones) were studied by the cross-correlation method using a white-noise-modulated light stimulus. Incremental responses were characterized by the kernels. White-noise-evoked responses with a peak-to-peak excursion of greater than 5 mV were linear, with mean square errors of approximately 8%, a degree of linearity comparable to the horizontal cell responses. Both a spot (0.17 mm diam) and a large field of light produced almost identical kernels. The amplitudes of receptor kernels obtained at various mean irradiances fitted approximately the Weber-Fechner relationship and the mean levels controlled both the amplitude and the response dynamics; kernels were slow and monophasic at low mean irradiance and were fast and biphasic at high mean irradiance. This is a parametric change and is a piecewise linearization. Horizontal cell kernels evoked by the small spot of light were monophasic and slower than the receptor kernels produced by the same stimulus. Larger spots of light or a steady annular illumination transformed the slow horizontal cell kernel into a fast kernel similar to those of the receptors. The slowing down of the kernel waveform was modeled by a simple low-pass circuit and the presumed feedback from horizontal cells onto cones did not appear to play a major role.


1988 ◽  
Vol 92 (6) ◽  
pp. 811-831 ◽  
Author(s):  
K Naka ◽  
R L Chappell ◽  
M Sakuranaga ◽  
H Ripps

The all-rod retina of the skate (Raja erinacea or R. oscellata) is known to have the remarkable capability of responding to incremental flashes superimposed on background intensities that initially block all light-evoked responses and are well above the level at which rods saturate in mixed rod/cone retinas. To examine further the unusual properties of the skate visual system, we have analyzed responses of their horizontal cells to intensity-modulated step, sinusoidal, and white-noise stimuli. We found that during exposures to mean intensities bright enough to block responses to incremental stimuli, decremental stimuli were also initially blocked. Thereafter, the horizontal cells underwent a slow recovery phase during which there was marked nonlinearity in their response properties. The cell first (within 2-3 min) responded to decrements in intensity and later (after greater than 10 min) became responsive to incremental stimuli. After adaptation to a steady state, however, the responses to intensity modulation were nearly linear over a broad range of modulation depths even at the brightest mean levels of illumination. Indeed, examination of the steady-state responses over a 5-log-unit range of mean intensities revealed that the amplitude of the white noise-evoked responses depended solely on contrast, and was independent of the retinal irradiance as the latter was increased from 0.02 to 20 muW/cm2; i.e., contrast sensitivity remained unchanged over this 1,000-fold increase in mean irradiance. A decrement from the mean as brief as 2 s, however, disturbed the steady state. Another unexpected finding in this all-rod retina concerns surround-enhancement, a phenomenon observed previously for cone-mediated responses of horizontal cells in the retinas of turtle and catfish. While exposure to annular illumination induced response compression and a pronounced sensitivity loss in response to incremental light flashes delivered to the dark central region, the cell's sensitivity showed a significant increase when tested with a white noise or sinusoidally modulated central spot. Unlike horizontal cells in other retinas studied thus far, however, response dynamics remained unchanged. Responses evoked either by a small spot (0.25-mm diam) or by a large field light covering the entire retina were almost identical in time course. This is in contrast with past findings from cone-driven horizontal cells whose response waveform (dynamics) was dependent upon the size of the retinal area stimulated.


1997 ◽  
Vol 78 (4) ◽  
pp. 2034-2047 ◽  
Author(s):  
Hiroko M. Sakai ◽  
Hildred Machuca ◽  
Michael J. Korenberg ◽  
Ken-Ichi Naka

Sakai, Hiroko M., Hildred Machuca, Michael J. Korenberg, and Ken-Ichi Naka. Processing of color- and noncolor-coded signals in the gourami retina. III. Ganglion cells. J. Neurophysiol. 78: 2034–2047, 1997. The dynamics of intracellular responses from ganglion cells, as well as that of spike discharges, were studied with the stimulus regimens and analytic procedures identical to those used to study the dynamics of the responses from horizontal and amacrine cells ( Sakai et al. 1997a , b ). The stimuli used were large fields of red and green light given as a pulsatile input or modulation about a mean luminance by a white-noise signal. Spike discharges evoked by a white-noise stimulus were analyzed in exactly the same manner as that used for analysis of analog responses. The canonical nature of kernels allowed us to correlate the first- and second-order components in a spike train with those of the intracellular responses from horizontal, amacrine, and ganglion cells. Both red and green stimuli given alone in darkness produced noncolor-coded responses from all ganglion cells. In the case of some cells, steady red illumination changed the polarity or waveform of the response to green light. Color-coded ganglions responded only to simultaneous color contrast. Nonlinearities recovered from intracellular responses, and spike discharges were similar to those found in responses from amacrine cells and were of two types, one characteristic of the C amacrine cells and the other characteristic of the N amacrine cells. The first-order kernels of most ganglion cells could be divided into two basic types, biphasic and triphasic. The combination of kernels of these two basic types with different polarities can produce a wide range of responses. Addition of two types of second-order nonlinearity could render color coding in this relatively simple retina as an extremely complex process. Color information appeared to be represented by the polarity, as well as the waveform, of the first-order kernel. The response dynamics is a means of transmission of color-coded information. Second-order components carry information about changes around a mean luminance regardless of the color of an input. Some spike discharges produced a well-defined cross-kernel between red and green inputs to show that a particular time sequence of red and green stimuli was detected by the retinal neuron network. The similarity between signatures of second-order kernels for both amacrine and ganglion cells indicates that signals undergo a minimal transformation in the temporal domain when they are transmitted from amacrine to ganglion cells and then transformed into a spike train. Under our experimental conditions, a single spike train carried simultaneously information about red and green inputs, as well as about linear and nonlinear components. In addition, the spike train also carries a cross-talk component. A spike train is a carrier of multiple signals. Conversely, many types of information in a stimulus are independently encoded into a spike train.


1989 ◽  
Vol 93 (4) ◽  
pp. 681-694 ◽  
Author(s):  
M Kamermans ◽  
B W van Dijk ◽  
H Spekreijse ◽  
R C Zweypfenning

The spatial and color coding of the monophasic horizontal cells were studied in light- and dark-adapted retinae. Slit displacement experiments revealed differences in integration area for the different cone inputs of the monophasic horizontal cells. The integration area measured with a 670-nm stimulus was larger than that measured with a 570-nm stimulus. Experiments in which the diameter of the test spot was varied, however, revealed at high stimulus intensities a larger summation area for 520-nm stimuli than for 670-nm stimuli. The reverse was found for low stimulus intensities. To investigate whether these differences were due to interaction between the various cone inputs to the monophasic horizontal cell, adaptation experiments were performed. It was found that the various cone inputs were not independent. Finally, some mechanisms for the spatial and color coding will be discussed.


1996 ◽  
Vol 76 (3) ◽  
pp. 2005-2019 ◽  
Author(s):  
W. A. Hare ◽  
W. G. Owen

1. It is widely believed that signals contributing to the receptive field surrounds of retinal bipolar cells pass from horizontal cells to bipolar cells via GABAergic synapses. To test this notion, we applied gamma-aminobutyric acid (GABA) agonists and antagonists to isolated, perfused retinas of the salamander Ambystoma tigrinum while recording intracellularly from bipolar cells, horizontal cells, and photoreceptors. 2. As we previously reported, administration of the GABA analogue D-aminovaleric acid in concert with picrotoxin did not block horizontal cell responses or the center responses of bipolar cells but blocked the surround responses of both on-center and off-center bipolar cells. 3. Surround responses were not blocked by the GABA, antagonists picrotoxin or bicuculline, the GABAB agonist baclofen or the GABAB antagonist phaclofen, and the GABAC antagonists picrotoxin or cis-4-aminocrotonic acid. Combinations of these drugs were similarly ineffective. 4. GABA itself activated a powerful GABA uptake mechanism in horizontal cells for which nipecotic acid is a competitive agonist. It also activated, both in horizontal cells and bipolar cells, large GABAA conductances that shunted light responses but that could be blocked by picrotoxin or bicuculline. 5. GABA, administered together with picrotoxin to block the shunting effect of GABAA activation, did not eliminate bipolar cell surround responses at concentrations sufficient to saturate the known types of GABA receptors. 6. Surround responses were not blocked by glycine or its antagonist strychnine, or by combinations of drugs designed to eliminate GABAergic and glycinergic pathways simultaneously. 7. Although we cannot fully discount the involvement of a novel GABAergic synapse, the simplest explanation of our findings is that the primary pathway mediating the bipolar cell's surround is neither GABAergic nor glycinergic.


Sign in / Sign up

Export Citation Format

Share Document