Synchronization of electrically coupled pairs of inhibitory interneurons in neocortex

Jaime G. Mancilla, Timothy J. Lewis, David J. Pinto, John Rinzel, Barry W. Connors

Research output: Contribution to journalArticlepeer-review


We performed a systematic analysis of phase locking in pairs of electrically coupled neocortical fast-spiking (FS) and low-threshold-spiking (LTS) interneurons and in a conductance-based model of a pair of FS cells. Phase-response curves (PRCs) were obtained for real interneurons and the model cells. We used PRCs and the theory of weakly coupled oscillators to make predictions about phase-locking characteristics of cell pairs. Phase locking and the robustness of phase-locked states to differences in intrinsic frequencies of cells were directly examined by driving interneuron pairs through a wide range of firing frequencies. Calculations using PRCs accurately predicted that electrical coupling robustly synchronized the firing of interneurons over all frequencies studied (FS, ∼25-80 Hz; LTS, ∼10-30 Hz). The synchronizing ability of electrical coupling and the robustness of the phase-locked states were directly dependent on the strength of coupling but not on firing frequency. The FS cell model also predicted the existence of stable antiphase firing at frequencies below ∼30 Hz, but no evidence for stable antiphase firing was found using the experimentally determined PRCs or in direct measures of phase locking in pairs of interneurons. Despite significant differences in biophysical properties of FS and LTS cells, their phase-locking behavior was remarkably similar. The wide spikes and shallow action potential afterhyperpolarizations of interneurons, compared with the model, prohibited antiphase behavior. Electrical coupling between cortical interneurons of the same type maintained robust synchronous firing of cell pairs for up to ∼10% heterogeneity in their intrinsic frequencies.

Original languageEnglish (US)
Pages (from-to)2058-2073
Number of pages16
JournalJournal of Neuroscience
Issue number8
StatePublished - Feb 21 2007


  • FS cell
  • Gap junctions
  • LTS cell
  • Oscillations
  • Phase-response curves
  • Synchrony
  • Whisker barrel

ASJC Scopus subject areas

  • General Neuroscience


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