Mechanism of High-Frequency Signaling at a Depressing Ribbon Synapse

Chad P. Grabner, Charles P. Ratliff, Adam C. Light, Steven H. DeVries*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)133-145
Number of pages13
JournalNeuron
Volume91
Issue number1
DOIs
StatePublished - Jul 6 2016

ASJC Scopus subject areas

  • Neuroscience(all)

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