Light evokes Ca2+ spikes in the axon terminal of a retinal bipolar cell

Dario A. Protti, Nicolas Flores-Herr, Henrique Von Gersdorff

Research output: Contribution to journalArticle

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Abstract

Bipolar cells in the vertebrate retina have been characterized as nonspiking interneurons. Using patch-clamp recordings from goldfish retinal slices, we find, however, that the morphologically well-defined Mb1 bipolar cell is capable of generating spikes. Surprisingly, in dark-adapted retina, spikes were reliably evoked by light flashes and had a long (1-2 s) refractory period. In light-adapted retina, most Mb1 cells did not spike. However, an L-type Ca2+ channel agonist could induce periodic spiking in these cells. Spikes were determined to be Ca2+ action potentials triggered at the axon terminal and were abolished by 2-amino-4-phosphonobutyric acid (APB), an agonist that mimics glutamate. Signaling via spikes in a specific class of bipolar cells may serve to accelerate and amplify small photoreceptor signals, thereby securing the synaptic transmission of dim and rapidly changing visual input.

Original languageEnglish (US)
Pages (from-to)215-227
Number of pages13
JournalNeuron
Volume25
Issue number1
DOIs
StatePublished - Jan 2000

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ASJC Scopus subject areas

  • Neuroscience(all)

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