Retinal bipolar cell input mechanisms in giant danio. III. ON-OFF bipolar cells and their color-opponent mechanisms

J Neurophysiol. 2005 Jul;94(1):265-72. doi: 10.1152/jn.00271.2004. Epub 2005 Mar 9.


Whole cell patch recording was performed from morphologically identified cone-driven on-off bipolar cells (Cabs) in giant danio retinal slices to study their glutamate receptors and light-evoked responses. Specific agonists were puffed in the presence of cobalt, picrotoxin, and strychnine to identify glutamate receptors on these cells. Most Cabs responded to both the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptor agonist kainate and the excitatory amino acid transporter (EAAT) substrate D-aspartate, and both responses were localized to the dendrites. Kainate generated depolarizations whereas D-aspartate had E(rev) close to E(Cl) and generated hyperpolarizations, indicating that the AMPA/kainate receptors are sign-preserving, whereas the EAATs are sign-inverting. In response to white light, some Cabs gave on bipolar cell-like responses whereas others gave off bipolar cell-like ones, but many cells' responses had both on and off bipolar cell components. In response to appropriately colored center-selective stimuli, many Cabs responded to short and long wavelengths with opposite polarities and were thus double color-opponent. The depolarizing components of the responses to white or colored stimuli were suppressed by the EAAT blocker DL-threo-beta-benzyloxyaspartate (TBOA), whereas the hyperpolarizing components were reduced by the AMPA/kainate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX). These results are consistent with the hypothesis that both EAATs and AMPA/kainate receptors are involved in the generation of light-evoked responses in Cabs and that they confer these cells with on and off bipolar cell properties, respectively. Cabs can generate double color-opponent center responses by receiving inputs from certain cones through EAATs and from other cones through AMPA/kainate receptors.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Aspartic Acid / pharmacology
  • Color*
  • D-Aspartic Acid / pharmacology
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • In Vitro Techniques
  • Kainic Acid / pharmacology
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Membrane Potentials / radiation effects
  • Neurons / classification
  • Neurons / drug effects
  • Neurons / physiology*
  • Neurons / radiation effects
  • Patch-Clamp Techniques
  • Photic Stimulation / methods
  • Propionates / pharmacology
  • Quinoxalines / pharmacology
  • Retina / cytology*
  • Visual Pathways / drug effects
  • Visual Pathways / physiology*
  • Visual Pathways / radiation effects
  • Zebrafish / physiology*


  • 2-amino-4-phosphono-propinate
  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • Propionates
  • Quinoxalines
  • benzyloxyaspartate
  • Aspartic Acid
  • D-Aspartic Acid
  • FG 9041
  • Kainic Acid