Figure 8. Synchronization to oscillating inhibition is controlled by g_Kt.

(a) Naturalistic stimulus protocol. The cell was stimulated with a constant step of AMPA conductance (g_AMPA, reversing at 0 mV) with added conductance Ornstein-Uhlenbeck noise (standard deviation 2% of the step amplitude, τ = 5 ms), combined with a sinusoidal GABA_A conductance (g_GABA, reversing at −60 mV) and introduction of positive, zero or negative g_Kt. g_AMPA was adjusted so that the cell fired close to the frequency of the g_GABA inhibitory oscillation. (b) Effect of adding g_Kt on a slightly irregular-firing cell at 10 Hz g_GABA. (i) Step current response (black), response to oscillatory conductance stimulus with (green) or without (blue) addition of 3.57 nS g_Kt. (ii) Spike entrainment synchrony (see Materials and methods, Spike Analysis) to the 10 Hz g_GABA oscillation as a function of the oscillation amplitude. Synchrony rises progressively with oscillation amplitude in control (blue), and is depressed by the addition of 3.57 nS g_Kt (green). (iii) Spike phase histogram for pooled responses to lower amplitude g_GABA oscillations (up to 1 nS), showing a reduction in the sharpness of synchrony. (c) Example of subtracting g_Kt in another irregular-firing cell at 10 Hz g_GABA. (i) example responses. (ii) Subtraction of g_Kt (red) increased synchrony to g_GABA oscillation over a wide range of amplitudes, when compared to control (blue). (iii) spike phase histograms for pooled responses up to 1 nS g_GABA oscillations. Subtraction of g_Kt enhances the phase preference. (d) Lack of effect of g_Kt on synchronization to 40 Hz (gamma) oscillation. (e) Summary of effects of g_Kt perturbation on synchrony in different cells. Each symbol denotes an experiment on an individual cell, showing the ratio of synchrony, evaluated at ≈1/3 of the maximum g_GABA amplitude applied in each case, during g_Kt injection, normalized to its control value with no injection. 10 Hz: g_Kt addition (n = 10, green) and subtraction, (n = 10, red); 40 Hz: g_Kt addition (n = 6, green) or subtraction (n = 7, red). At 10 Hz, but not 40 Hz, g_Kt perturbation has a significant effect. Wilcoxon nonparametric rank sum test, p=6.5 × 10^–5 for both positive and negative g_Kt, and p=0.36 and 0.69 at 40 Hz for positive and negative g_Kt respectively.

DOI: http://dx.doi.org/10.7554/eLife.16475.023