TY - JOUR T1 - Synchronization of Electrically Coupled Pairs of Inhibitory Interneurons in Neocortex JF - The Journal of Neuroscience JO - J. Neurosci. SP - 2058 LP - 2073 DO - 10.1523/JNEUROSCI.2715-06.2007 VL - 27 IS - 8 AU - Jaime G. Mancilla AU - Timothy J. Lewis AU - David J. Pinto AU - John Rinzel AU - Barry W. Connors Y1 - 2007/02/21 UR - http://www.jneurosci.org/content/27/8/2058.abstract N2 - 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. ER -