Activity deprivation reduces miniature IPSC amplitude by decreasing the number of postsynaptic GABAA receptors clustered at neocortical synapses

Valerie Kilman, Mark C W Van Rossum, Gina G. Turrigiano*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

307 Scopus citations

Abstract

Maintaining the proper balance between excitation and inhibition is necessary to prevent cortical circuits from either falling silent or generating epileptiform activity. One mechanism through which cortical networks maintain this balance is through the activity-dependent regulation of inhibition, but whether this is achieved primarily through changes in synapse number or synaptic strength is not clear. Previously, we found that 2 d of activity deprivation increased the amplitude of miniature EPSCs (mEPSCs) onto cultured visual cortical pyramidal neurons. Here we find that this same manipulation decreases the amplitude of mIPSCs. This occurs with no change in single-channel conductance but is accompanied by a reduction in the average number of channels open during the mIPSC peak and a reduction in the intensity of staining for GABAA receptors (GABAARs) at postsynaptic sites. In addition, the number of synaptic sites that express detectable levels of GABAARs was decreased by ∼50% after activity blockade, although there was no reduction in the total number of presynaptic contacts. These data suggest that activity deprivation reduces cortical inhibition by reducing both the number of GABAARs clustered at synaptic sites and the number of functional inhibitory synapses. Because excitatory and inhibitory synaptic currents are regulated in opposite directions by activity blockade, these data suggest that the balance between excitation and inhibition is dynamically regulated by ongoing activity.

Original languageEnglish (US)
Pages (from-to)1328-1337
Number of pages10
JournalJournal of Neuroscience
Volume22
Issue number4
DOIs
StatePublished - Feb 15 2002

Keywords

  • Activity-dependent
  • GABA receptor
  • Nonstationary fluctuation analysis
  • Synapse elimination
  • Synaptic plasticity
  • mIPSC

ASJC Scopus subject areas

  • Neuroscience(all)

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