Brief dark exposure reduces tonic inhibition in visual cortex

Shiyong Huang, Kristen Hokenson, Sabita Bandyopadhyay, Shelley J. Russek, Alfredo Kirkwood

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Tonic inhibition mediated by extrasynaptic GABAA receptors (GABARs) sensing ambient levels of GABA can profoundly alter the membrane input resistance to affect cellular excitability. Therefore, regulation of tonic inhibition is an attractive mechanism to control the levels of cortical firing. In cortical pyramidal cells, tonic inhibition is regulated by age and several neurotransmitters and is affected by stroke and epilepsy. However, the possible role of sensory experience has not been examined. Here, we report that a brief 2-day exposure to dark reduces by 1/3 the inhibitory tonic conductance recorded in layer II/III pyramidal cells of the mouse juvenile (postnatal day 12-27) visual cortex. In these cells, tonic inhibition is carried primarily by GABARs containing the δ subunit. Consistently, the dark exposure reduction in conductance was associated with a reduction in δ subunit levels, which were not affected in control frontal cortex. We propose that a deprivation-induced reduction in tonic inhibition might serve a homeostatic function by increasing the firing levels of cells in deprived cortical circuits.

Original languageEnglish (US)
Pages (from-to)15916-15920
Number of pages5
JournalJournal of Neuroscience
Issue number48
StatePublished - Dec 2 2015


  • Extrasynaptic receptors
  • Layer 2/3
  • Pyramidal cells
  • δ-GABA receptor

ASJC Scopus subject areas

  • General Neuroscience


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