Fig. 4.

Dynamics of intermittent oscillations represented in three continuous model variables. A fluctuation in external inputs (data not shown) increases the RS and FS population-averaged instantaneous firing rates (dark green). The recurrent interaction between RS and FS neurons mediates oscillations. The coordinated activity of RS neurons activates LTS neurons. Because of the long decay of LTS synaptic conductances in other neurons, the population-averaged conductance accumulates. This accumulation causes a decline in RS and FS activity, which in turn terminates the oscillatory RS and FS activity. The vanishing coordinated activity in RS neurons causes a decline in LTS activity (light green). In this parametric plot the state of the network at a certain time is represented by a dot within 3-dimensional space spanned by the 150-Hz low-pass-filtered RS and FS instantaneous firing rates and the population-averaged LTS conductance in all neurons. Dots are plotted for 500 ms with time increments of Δt = 0.5 ms. Time increases from dark green to light green.