Figure 1.

Theta oscillations in a sparsely interconnected network of 250 IB neurons stimulated by a heterogeneous current. (a) Raster plot of spike times of each neuron (bottom-to-top: cell 1 initially most hyperpolarized, cell 250 initially most depolarized) shows the evolution of theta oscillations. (b) Post-stimulus spike histogram (bin size 1 ms) of coupled network in (a) shows rhythmic firing of cells at a steady-state burst frequency of 4.65 Hz (215 ms interval) within the theta-band. (c) Post-stimulus spike histogram of uncoupled (control) network shows that after a stimulus-induced burst artefact there was no rhythmic population spiking. (d) Temporary withdrawal of driving current for 500 ms (600–1100 ms period) of simulation shown in (a) eliminated population bursting but rhythmic firing recovered after the driving current was reapplied.