Inhibitory network properties shaping the light evoked responses of cat alpha retinal ganglion cells

Vis Neurosci. Jul-Aug 2003;20(4):351-61. doi: 10.1017/s0952523803204016.

Abstract

Cat retinal ganglion cells of the Y (or alpha) type respond to luminance changes opposite those preferred by their receptive-field centers with a transient hyperpolarization. Here, we examine the spatial organization and synaptic basis of this light response by means of whole-cell current-clamp recordings made in vitro. The hyperpolarization was largest when stimulus spots approximated the size of the receptive-field center, and diminished substantially for larger spots. The hyperpolarization was largely abolished by bath application of strychnine, a blocker of glycinergic inhibition. Picrotoxin, an antagonist of ionotropic GABA receptors, greatly reduced the attenuation of the hyperpolarizing response for large spots. The data are consistent with a model in which (1) the hyperpolarization reflects inhibition by glycinergic amacrine cells of bipolar terminals presynaptic to the alpha cells, and perhaps direct inhibition of the alpha cell as well; and (2) the attenuation of the hyperpolarization by large spots reflects surround inhibition of the glycinergic amacrine by GABAergic amacrine cells. This circuitry may moderate nonlinearities in the alpha-cell light response and could account for some excitatory and inhibitory influences on alpha cells known to arise from outside the classical receptive field.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amacrine Cells / physiology
  • Animals
  • Cats
  • Electrophysiology
  • Glycine / physiology
  • In Vitro Techniques
  • Light*
  • Nerve Net / physiology*
  • Neural Inhibition / physiology*
  • Photic Stimulation / methods
  • Retinal Ganglion Cells / physiology*
  • Retinal Ganglion Cells / radiation effects*
  • Synaptic Transmission
  • gamma-Aminobutyric Acid / physiology

Substances

  • gamma-Aminobutyric Acid
  • Glycine