The Open- and Closed-Loop Gain-Characteristics of the Cone/Horizontal Cell Synapse in Goldfish Retina

Kraaij, D.A.; Spekreijse, H.; Kamermans, Maarten

doi:10.1152/jn.2000.84.3.1256

Cited by 22 publications

(13 citation statements)

References 51 publications

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“…The parameters for this simulation are given in Table 1. These values were in the same range as the values determined and used by Verweij et al (1996), Fahrenfort et al (1999) and Kraaij et al (2000b). Figure 5A gives the simulated Ca 2+ currents without (continuous line) and with maximal feedback (dashed line).…”

Section: Figurementioning

confidence: 67%

The dynamic characteristics of the feedback signal from horizontal cells to cones in the goldfish retina

Kamermans¹,

Kraaij²,

Spekreijse

2001

The Journal of Physiology

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The dynamic properties of the microcircuitry formed by cones and horizontal cells in the isolated goldfish retina were studied. Cones project to horizontal cells and horizontal cells feed back to cones via a relatively slow negative feedback pathway. The time constant of the feedback signal in cones and of the effect this feedback signal had on the responses of second‐order neurons was determined using whole‐cell patch clamp and intracellular recording techniques. It was found that the feedback signal in cones had a time constant of around 80 ms, whereas the time constant of the effect this feedback signal had on the second‐order neurons ranged from 36 to 116 ms. This range of time constants can be accounted for by the non‐linearity of the Ca2+ current in the cones. In depolarized cones, the feedback‐mediated response in second‐order neurons had a similar time constant to that of the direct light response of the cone, whereas in hyperpolarized cones, the time constant of the feedback‐mediated response in second‐order neurons was considerably larger. Further, it was shown that there was no delay in the feedback pathway. This is in contrast to what has been deduced from the response properties of second‐order neurons. In one type of horizontal cell, the responses to red light were delayed relative to the responses to green light. This delay in the second‐order neurons can be accounted for by the interaction of the direct light response of the medium‐wavelength‐sensitive cones (M‐cones) with the feedback response of the M‐cones received from the horizontal cells.

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Section: Figurementioning

confidence: 67%

The dynamic characteristics of the feedback signal from horizontal cells to cones in the goldfish retina

Kamermans¹,

Kraaij²,

Spekreijse

2001

The Journal of Physiology

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“…in the range of physiological membrane potentials, depends linearly on horizontal cell membrane potential () [48]. The solid line in Fig.…”

Section: Resultsmentioning

confidence: 94%

Hemichannel-Mediated and pH-Based Feedback from Horizontal Cells to Cones in the Vertebrate Retina

et al. 2009

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BackgroundRecent studies designed to identify the mechanism by which retinal horizontal cells communicate with cones have implicated two processes. According to one account, horizontal cell hyperpolarization induces an increase in pH within the synaptic cleft that activates the calcium current (Ca2+-current) in cones, enhancing transmitter release. An alternative account suggests that horizontal cell hyperpolarization increases the Ca2+-current to promote transmitter release through a hemichannel-mediated ephaptic mechanism.Methodology/Principal FindingsTo distinguish between these mechanisms, we interfered with the pH regulating systems in the retina and studied the effects on the feedback responses of cones and horizontal cells. We found that the pH buffers HEPES and Tris partially inhibit feedback responses in cones and horizontal cells and lead to intracellular acidification of neurons. Application of 25 mM acetate, which does not change the extracellular pH buffer capacity, does lead to both intracellular acidification and inhibition of feedback. Because intracellular acidification is known to inhibit hemichannels, the key experiment used to test the pH hypothesis, i.e. increasing the extracellular pH buffer capacity, does not discriminate between a pH-based feedback system and a hemichannel-mediated feedback system. To test the pH hypothesis in a manner independent of artificial pH-buffer systems, we studied the effect of interfering with the endogenous pH buffer, the bicarbonate/carbonic anhydrase system. Inhibition of carbonic anhydrase allowed for large changes in pH in the synaptic cleft of bipolar cell terminals and cone terminals, but the predicted enhancement of the cone feedback responses, according to the pH-hypothesis, was not observed. These experiments thus failed to support a proton mediated feedback mechanism. The alternative hypothesis, the hemichannel-mediated ephaptic feedback mechanism, was therefore studied experimentally, and its feasibility was buttressed by means of a quantitative computer model of the cone/horizontal cell synapse.ConclusionWe conclude that the data presented in this paper offers further support for physiologically relevant ephaptic interactions in the retina.

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“…Investigators of the goldfish retina and of the catfish retina have found evidence for the idea that horizontal--cone feedback modulates synaptic transmission at the ribbon synapse, and this modulation makes synaptic transmission more linear (Verweij et al 1996; Kraaij et al, 2000; Sakai and Naka 1987). Kraaij et al (2000) hypothesized that the early response of horizontal cells to a step increment of illumination was driven “open-loop” by the cones, while the later part of the step response was “closed-loop”, that is, influenced by horizontal--cone feedback. When they studied open-loop and closed-loop responses to different light intensities, they found that the ratio of horizontal/cone responses (what they called the gain of the cone synapse) was fairly linear--that is, proportional to light intensity--for the closed-loop response (Figure 5B), but quite nonlinear for the open-loop condition (Figure 5A).…”

Section: Mechanisms Of Retinal Linearity--ribbon Synapsesmentioning

confidence: 99%

“…Cone--horizontal transmission in goldfish retina (Kraaij et al 2000). The “open loop” early response ( A ) and “closed loop” from the later response ( B ) are gain-characteristic functions from cone to horizontal cells (HC) (solid lines).…”

Section: Figuresmentioning

confidence: 99%

Linear and nonlinear systems analysis of the visual system: Why does it seem so linear?

Shapley

2009

Vision Research

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Linear and nonlinear systems analysis are tools that can be used to study communication systems like the visual system. The first step of systems analysis often is to test whether or not the system is linear. Retinal pathways are surprisingly linear, and some neurons in the visual cortex also emulate linear sensory transducers. We conclude that the retinal linearity depends on specialized ribbon synapses while cortical linearity is the result of balanced excitatory and inhibitory synaptic interactions.

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The Open- and Closed-Loop Gain-Characteristics of the Cone/Horizontal Cell Synapse in Goldfish Retina

Cited by 22 publications

References 51 publications

The dynamic characteristics of the feedback signal from horizontal cells to cones in the goldfish retina

The dynamic characteristics of the feedback signal from horizontal cells to cones in the goldfish retina

Hemichannel-Mediated and pH-Based Feedback from Horizontal Cells to Cones in the Vertebrate Retina

Linear and nonlinear systems analysis of the visual system: Why does it seem so linear?

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