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Updated: Aug 7, 2026

Simultaneous Whole-cell Recordings from Photoreceptors and Second-order Neurons in an Amphibian Retinal Slice Preparation
Published on: June 1, 2013
Light evokes Ca2+ spikes in the axon terminal of a retinal bipolar cell
D A Protti1, N Flores-Herr, H von Gersdorff
1Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany. protti@mpih-frankfurt.mpg.de
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 photo-receptor signals, thereby securing the synaptic transmission of dim and rapidly changing visual input.
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