1. Mechanism of High-Frequency Signaling at a Depressing Ribbon Synapse.
- Author
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Grabner CP, Ratliff CP, Light AC, and DeVries SH
- Subjects
- Animals, Calcium metabolism, Electric Stimulation methods, Exocytosis physiology, Synaptic Transmission physiology, Excitatory Postsynaptic Potentials physiology, Retina physiology, Retinal Bipolar Cells metabolism, Retinal Cone Photoreceptor Cells metabolism, Signal Transduction physiology, Synapses physiology
- Abstract
Ribbon synapses mediate continuous release in neurons that have graded voltage responses. While mammalian retinas can signal visual flicker at 80-100 Hz, the time constant, τ, for the refilling of a depleted vesicle release pool at cone photoreceptor ribbons is 0.7-1.1 s. Due to this prolonged depression, the mechanism for encoding high temporal frequencies is unclear. To determine the mechanism of high-frequency signaling, we focused on an "Off" cone bipolar cell type in the ground squirrel, the cb2, whose transient postsynaptic responses recovered following presynaptic depletion with a τ of ∼0.1 s, or 7- to 10-fold faster than the τ for presynaptic pool refilling. The difference in recovery time course is caused by AMPA receptor saturation, where partial refilling of the presynaptic pool is sufficient for a full postsynaptic response. By limiting the dynamic range of the synapse, receptor saturation counteracts ribbon depression to produce rapid recovery and facilitate high-frequency signaling., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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