Light-Evoked Oscillatory Discharges in Retinal Ganglion Cells Are Generated by Rhythmic Synaptic Inputs

DOI Web Site 被引用文献3件
  • Itaru Arai
    Department of Psychology, Graduate School of Humanities and Sociology, The University of Tokyo, Tokyo 113-0033, Japan
  • Yoshiyuki Yamada
    Department of Psychology, Graduate School of Humanities and Sociology, The University of Tokyo, Tokyo 113-0033, Japan
  • Tomomitsu Asaka
    Department of Psychology, Graduate School of Humanities and Sociology, The University of Tokyo, Tokyo 113-0033, Japan
  • Masao Tachibana
    Department of Psychology, Graduate School of Humanities and Sociology, The University of Tokyo, Tokyo 113-0033, Japan

抄録

<jats:p> 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<jats:sup>+</jats:sup> 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 GABA<jats:sub>A</jats:sub> receptor antagonist but potentiated by a GABA<jats:sub>C</jats:sub> 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. </jats:p>

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