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Horizontal cells feed back to cones by shifting the cone calcium-current activation range
J Verweij1, M Kamermans, H Spekreijse
1Graduate School Neurosciences, Amsterdam, The Netherlands.
Vision Research
|December 1, 1996
Summary
Horizontal cells in goldfish retinas provide feedback to cones, modulating their calcium currents and synaptic output. This feedback mechanism, triggered by surround stimuli, influences cone light sensitivity and visual processing.
Area of Science:
- Neuroscience
- Retinal Physiology
- Visual System Research
Background:
- Horizontal cells play a crucial role in retinal processing.
- Feedback mechanisms in the retina are essential for visual adaptation.
Purpose of the Study:
- To investigate the nature of feedback from horizontal cells to cones in goldfish retina.
- To elucidate the ionic mechanisms and functional consequences of this feedback.
Main Methods:
- Electrophysiological recordings from isolated goldfish retina.
- Application of glutamate antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX).
- Modulation of extracellular GABA concentration.
Main Results:
- Surround stimuli evoked inward and outward currents in cones, mediated by horizontal cell feedback.
- The inward current was calcium-dependent and triggered a chloride current.
- Feedback shifted cone calcium-current activation to more negative potentials.
Conclusions:
- Horizontal cell feedback directly targets cone calcium currents.
- This feedback modulates cone synaptic output without significantly altering membrane potential.
- The findings offer insights into retinal circuit function and visual adaptation.