Light-evoked oscillatory discharges in retinal ganglion cells are generated by rhythmic synaptic inputs

Itaru Arai, Yoshiyuki Yamada, Tomomitsu Asaka, Masao Tachibana

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

In the visual system, optimal light stimulation sometimes generates γ-range (ca. 20 ∼ 80 Hz) synchronous oscillatory spike discharges. This phenomenon is assumed to be related to perceptual integration. Applying a planar multi-electrode array to the isolated frog retina, Ishikane et al. demonstrated that dimming detectors, off-sustained type ganglion cells, generate synchronous oscillatory spike discharges in response to diffuse dimming illumination. In the present study, applying the whole cell current-clamp technique to the isolated frog retina, we examined how light-evoked oscillatory spike discharges were generated in dimming detectors. Light-evoked oscillatory (∼30 Hz) spike discharges were triggered by rhythmic (∼30 Hz) fluctuations superimposed on a depolarizing plateau potential. When a suprathreshold steady depolarizing current was injected into a dimming detector, only a few spikes were evoked at the stimulus onset. However, repetitive spikes were triggered by a γ-range sinusoidal current superimposed on the steady depolarizing current. Thus the light-evoked rhythmic fluctuations are likely to be generated presynaptically. The light-evoked rhythmic fluctuations were suppressed not by intracellular application of N-(2,6-dimethyl- phenylcarbamoylmethyl)triethylammonium bromide (QX-314), a Na+ channel blocker, to the whole cell clamped dimming detector but by bath-application of tetrodotoxin to the retina. The light-evoked rhythmic fluctuations were suppressed by a GABAA receptor antagonist but potentiated by a GABAC receptor antagonist, whereas these fluctuations were little affected by a glycine receptor antagonist. Because amacrine cells are spiking neurons and because GABA is one of the main transmitters released from amacrine cells, amacrine cells may participate in generating rhythmically fluctuated synaptic input to dimming detectors.

Original languageEnglish
Pages (from-to)715-725
Number of pages11
JournalJournal of Neurophysiology
Volume92
Issue number2
DOIs
Publication statusPublished - 2004 Aug 1
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

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