Synaptic mechanisms of forward suppression in rat auditory cortex

Neuron. 2005 Aug 4;47(3):437-45. doi: 10.1016/j.neuron.2005.06.009.


In the auditory cortex, brief sounds elicit a powerful suppression of responsiveness that can persist for hundreds of milliseconds. This forward suppression (sometimes also called forward masking) has usually been attributed to synaptic (GABAergic) inhibition. Here we have used whole-cell recordings in vivo to assess the role of synaptic inhibition in forward suppression in auditory cortex. We measured the excitatory and inhibitory synaptic conductances elicited by pairs of brief sounds presented at intervals from tens to hundreds of milliseconds. We find that inhibitory conductances rarely last longer than 50-100 ms, whereas spike responses and synaptic inputs remain suppressed for hundreds of milliseconds. We conclude that postsynaptic inhibition contributes to forward suppression for only the first 50-100 ms after a stimulus and that intracortical contributions to long-lasting suppression must involve other mechanisms, such as synaptic depression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Auditory Cortex / physiology*
  • Barbiturates / pharmacology
  • Electric Conductivity
  • Electrophysiology
  • Long-Term Synaptic Depression / physiology*
  • Neural Inhibition / physiology
  • Rats
  • Receptors, GABA-B / physiology
  • Synapses / drug effects
  • Synapses / physiology*
  • Time Factors


  • Barbiturates
  • Receptors, GABA-B