The visuo-motor pathway in the local circuit of the rat superior colliculus

J Neurosci. 1998 Oct 15;18(20):8496-504. doi: 10.1523/JNEUROSCI.18-20-08496.1998.


Intrinsic circuit of the superior colliculus (SC), in particular the pathway from the optic tract (OT) to neurons in the intermediate layer (SGI), was investigated by whole-cell patch-clamp recording in slice preparations obtained from 17- to 24-d-old rats. Stimulation of the OT induced monosynaptic EPSPs in neurons in the superficial gray layer (SGS) and the optic layer (SO), and disynaptic or polysynaptic EPSPs in a majority of SGI neurons. Stimulation of the SGS induced monosynaptic or oligosynaptic EPSPs in the SGI neurons. Both the monosynaptic EPSPs induced in the SGS/SO neurons by stimulation of the OT and those induced in the SGI neurons by stimulation of the SGS were mediated by AMPA- and NMDA-type glutamate receptors. Thus, we have clarified the existence of the glutamatergic excitatory pathway from the OT to the SGI neurons via SGS and SO neurons. The EPSPs in the SGI neurons induced by stimulation of the OT or SGS were remarkably enhanced by bicuculline, suggesting that the signal transmission in this pathway is under strong suppression by the GABAergic system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2-Amino-5-phosphonovalerate / pharmacology
  • 6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Bicuculline / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Postsynaptic Potentials / drug effects
  • Excitatory Postsynaptic Potentials / physiology
  • GABA Antagonists / pharmacology
  • Motor Neurons / physiology*
  • Neural Inhibition / physiology
  • Organ Culture Techniques
  • Patch-Clamp Techniques
  • Rats
  • Rats, Wistar
  • Superior Colliculi / cytology*
  • Superior Colliculi / physiology*
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology
  • Visual Pathways / physiology*
  • gamma-Aminobutyric Acid / physiology


  • Excitatory Amino Acid Antagonists
  • GABA Antagonists
  • gamma-Aminobutyric Acid
  • 6-Cyano-7-nitroquinoxaline-2,3-dione
  • 2-Amino-5-phosphonovalerate
  • Bicuculline