Fig. 6.

Orientation tuning curves for a ring model containing excitatory and inhibitory neurons of both simple (dashed) and complex (solid) type, computed from numerical simulations of an I&F network. (a) A mean-driven state with negligible fluctuations. Note the characteristics of a mean-driven, high-conductance state: abnormally high firing rates in the complex cell, together with the very low firing rates of the simple cell; the sharp transition in the firing rate of the complex cell as a function of θ; and the strong synchrony in the firing patterns of the complex cells (as shown in the raster plot inset). (b) A fluctuation-driven state. Note the more reasonable firing rates, their more gradual behavior as a function of θ, and the absence of synchrony in the firing patterns of the complex cells (again shown in the raster plot inset).