scholarly journals Interactions leading to horizontal cell responses in the turtle retina

1974 ◽  
Vol 240 (1) ◽  
pp. 177-198 ◽  
Author(s):  
M. G. F. Fuortes ◽  
E. J. Simon
Keyword(s):  
Horizontal Cell ◽  
Cell Responses

Contribution of rod, on-bipolar, and horizontal cell light responses to the ERG of dogfish retina

1999 ◽  
Vol 16 (3) ◽  
pp. 503-511 ◽  
Author(s):  
R.A. SHIELLS ◽  
G. FALK
Keyword(s):  
Bipolar Cell ◽  
Time Course ◽  
Horizontal Cell ◽  
Full Range ◽  
Bipolar Cells ◽  
Horizontal Cells ◽  
Negative Wave ◽  
Low Light ◽  
Cell Responses ◽  
Light Intensities

Simultaneous extracellular ERG and intracellular recordings from horizontal and ON-bipolar cells were obtained from the dark-adapted retina of the dogfish. The light intensity–peak response relation (IR) and time course of on-bipolar cell responses closely resembled that of the ERG b-wave, but only at low light intensities [<10 rhodopsin molecules bleached per rod (Rh*)]. Block of on-bipolar cell responses with 50 μM 2-amino-4-phosphonobutyrate (APB) abolished the b-wave and unmasked a vitreal-negative wave. Subtraction from the control ERG resulted in the isolation of a vitreal-positive ERG with an IR which matched that of on-bipolar cells over the full range of light intensities. The D.C. component of the ERG arises as a result of sustained depolarization of on-bipolar cells in response to long (>0.5 s) dim light stimuli, or following bright light flashes. The IR of horizontal cells and the vitreal-negative wave unmasked by APB could be matched by scaling at low light intensities (<5 Rh*). However, horizontal cell responses saturated at about 30 Rh*, while the vitreal-negative wave continued to increase in amplitude. The time course of horizontal cell membrane current with dim flashes could be matched to the rising phase of the vitreal-negative wave, assuming that the delay in generating the voltage response in horizontal cells is due to their long (100 ms) membrane time constant. Blocking post-photoreceptor activity resulted in a much smaller vitreal-negative wave than that unmasked by APB alone. We conclude that the b-wave arises from on-bipolar cell depolarization, while the leading edge of the a-wave is a composite of the change in extracellular voltage drop across the rod layer and a component (proximal PIII) reflecting a decrease in extracellular K+ as horizontal cell synaptic channels close with light.

scholarly journals Reconstruction of retinal horizontal cell responses by the ionic current model

1996 ◽  
Vol 36 (12) ◽  
pp. 1711-1719 ◽  
Author(s):  
Shiro Usui ◽  
Yoshimi Kamiyama ◽  
Hiroyuki Ishii ◽  
Hidetoshi Ikeno
Keyword(s):  
Current Model ◽  
Horizontal Cell ◽  
Ionic Current ◽  
Cell Responses

scholarly journals Analyses of bipolar cell responses elicited by polarization of horizontal cells.

1982 ◽  
Vol 79 (1) ◽  
pp. 131-145 ◽  
Author(s):  
J Toyoda ◽  
T Kujiraoka
Keyword(s):  
Bipolar Cell ◽  
Horizontal Cell ◽  
Bipolar Cells ◽  
Horizontal Cells ◽  
Na Channels ◽  
Cell Responses ◽  
Ionic Mechanisms ◽  
Cl Channels ◽  
Hyperpolarizing Response ◽  
Conductance Changes

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.

scholarly journals Lateral feedback from monophasic horizontal cells to cones in carp retina. II. A quantitative model.

1989 ◽  
Vol 93 (4) ◽  
pp. 695-714 ◽  
Author(s):  
M Kamermans ◽  
B W van Dijk ◽  
H Spekreijse
Keyword(s):  
Receptive Field ◽  
Horizontal Cell ◽  
Quantitative Model ◽  
Field Amplitude ◽  
Horizontal Cells ◽  
Spatial Coding ◽  
Cell Responses ◽  
Amplitude Profile ◽  
Feedback Pathways ◽  
Distinct Role

About half of the monophasic horizontal cells in carp retina receive input from both red- and green-sensitive cones. Since the horizontal cells feed back to cones, the color and feedback pathways result in wavelength- and intensity-dependent changes of the dynamics and of the receptive field amplitude profile of the horizontal cell responses. In this paper we present a quantitative model that describes adequately the color and spatial coding and the dynamics of the responses from monophasic horizontal cells in carp. Lateral feedback plays a distinct role in this model.

Effects of synaptic blocking agents on the depolarizing responses of turtle cones evoked by surround illumination

1990 ◽  
Vol 5 (6) ◽  
pp. 571-583 ◽  
Author(s):  
Wallace B. Thoreson ◽  
Dwight A. Burkhardt
Keyword(s):  
Receptive Field ◽  
Excitatory Amino Acid ◽  
Horizontal Cell ◽  
Current Injection ◽  
Horizontal Cells ◽  
Light Responses ◽  
Calcium Dependent ◽  
Cell Responses ◽  
Blocking Agents ◽  
Amino Acid Antagonists

AbstractThe effects of synaptic blocking agents on the antagonistic surround of the receptive field of cone photoreceptors were studied intracellular recording in the retina of hte turtle (Pseudemys scripta elegans) Illumination of a cone's receptive-field surround typically evoked a hybriid depolarizing response composed of two componests: (1) the graded synaptic feedback depolarization and (2) the prolonged depolarization a distinctive, intrinsic response of the cone. The locus of action of synaptic blocking agents was analyzed by comparing their effects on the light-evoked response of horizontal cells, the hybrid cone depolarization evoked by surround illumination, and the pure prolonged depolarization evoked by intracellular current injection.The excitatory amino-acid antagonists, d-O-phosphoserine (DOS) and kynurenic acid (KynA), suppressed the light responses of horizontal cells and eliminated the surround-evoked, hybrid cone depolarization without affecting the prolonged depolarization evoked by current injection. Cobalt at 5–10 mM suppressed horizontal cell responses and thereby eliminated surround-evoked cone depolarizations. Cobalt (5–10 mM) also blocked the current-evoked prolonged depolarization, suggesting that the intrinsic cone mechanisms responsible for the prolonged depolarization are likely to be calcium-dependent.Various GABA agonists and antagonists were found to have no effect on the surround-evoked depolarizations of cones. In contrast, a very low concentration of cobalt (0.5 mM) selectively suppressed the light-evoked feedback depolarization of cones without affecting horizontal cell responses or the current-evoked prolonged depolarization. Cobalt at 0.5 mM thus blocks the light-evoked action of the cone feedback synapse while sparing feedforward synaptic transmission from cones to horizontal cells. The implications of the present work for the possible neurotransmitters used at these synapses is discussed.

Dark-suppression and light-sensitization of horizontal cell responses in the hybrid bass retina

1995 ◽  
Vol 12 (4) ◽  
pp. 611-620 ◽  
Author(s):  
William H. Baldridge ◽  
Reto Weiler ◽  
John E. Dowling
Keyword(s):  
Response Time ◽  
Horizontal Cell ◽  
Time Of Day ◽  
Horizontal Cells ◽  
Continuous Illumination ◽  
Constant Darkness ◽  
Peak Response ◽  
Cell Responses ◽  
Significant Difference ◽  
Short Time

AbstractThe responsiveness of luminosity-type horizontal cells, recorded intracellularly from isolated hybrid bass retinas, decreased after superfusion for 2 h in constant darkness. Responsiveness was subsequently increased (light-sensitized) up to 10-fold after exposure to several short (~0.5 min) periods of continuous illumination. The increase in horizontal cell responsiveness following light-sensitization was due to an increase of peak response amplitude rather than a reduction of peak response time. The increased responsiveness after light-sensitization was intensity-dependent with brighter sensitizing stimuli causing a greater increase than dimmer stimuli. The extent of LHC dark-suppression was affected by the time of day, being greater when induced during the night than during the day. However, there was no significant difference in horizontal cell responsiveness after light-sensitization in retinas studied during the night compared to those studied during the day The responsiveness of light-sensitized horizontal cells from isolated hybrid bass retinas was found to be suppressed by relatively brief periods of darkness. The responsiveness of horizontal cells, that were first light-sensitized, decreased by more than 50% following only 5 min of darkness. Suppression of light-sensitized horizontal cell responsiveness after such a short time in the dark has not been described in other teleost retinas. The suppression of light-sensitized horizontal cell responsiveness in hybrid bass retinas may be rapid in comparison to other teleosts.

Asymmetrical dynamics of voltage spread in retinal horizontal cell networks

2001 ◽  
Vol 18 (5) ◽  
pp. 835-848 ◽  
Author(s):  
J. BENDA ◽  
R. BOCK ◽  
P. RUJAN ◽  
J. AMMERMÜLLER
Keyword(s):  
Linear Model ◽  
Continuum Model ◽  
Temporal Dynamics ◽  
Light Stimulus ◽  
Horizontal Cell ◽  
Diffusion Term ◽  
Cell Network ◽  
Cell Responses ◽  
The Impact ◽  
Cell Networks

Lateral voltage spread in electrically coupled retinal horizontal cell networks is the substrate of center-surround antagonism in bipolar and ganglion cells. We studied its spatial and temporal properties in more detail in turtle L1 horizontal cells by using a contrast border as light stimulus. Experimental data were contrasted with expectations from a linear continuum model to specify the impact of nonlinearities. The assumptions for the diffusion term of the continuum model were justified by neurobiotin labeling. Measured voltage spread revealed two different length constants Λ+ and Λ0, under illuminated and nonilluminated regions of the retina, respectively, as predicted by the linear model. Length constants in the illuminated region showed strong temporal dynamics. For the initial phase of the horizontal cell responses Λ+ was larger than Λo. This was also in accordance with the model. Right at the peak of the response, however, Λ+ dropped below Λo and did not change any more. It is this temporal reversal of asymmetry in voltage spread and not the decrease of Λ+ itself that is lacked by the linear model. The observed independence of the mean ratio Λ+/Λo from light intensity in both the peak and the plateau phases of horizontal cell responses contradicts the linear assumption, too. These two effects have to be addressed to local nonlinearities in the horizontal cell network like a negative feedback loop from photoreceptors and/or voltage-dependent conductances. Due to the failure of the linear model, firm conclusions about the membrane resistance and the coupling resistance of the horizontal cell network cannot be drawn from length constant measurements.

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