Waves in a simple inhibitorily coupled network of PIR neurons

A network of neurons is coupled via GABA_A synapses. Each "cell" has only three currents: (i) a passive leak current; (ii) a low threshold inactivating calcium (T) current and (iii) the synaptic current.

• Figure 1A In this figure, the coupling between cells is localized with a maximum at zero distance and the waves show a characteristic lurching appearance. A brief localized stimulus is given to initiate the wave. This leaves clustered activity in the wake of the wave.
• Figure 2A This is identical to the previous figure except that there is a gap in the coupling so that cells that are within a small distance of the presynaptic cell do not receive any input from that cell. The result is smooth propagation to the left and lurching to the right. Periodic wave trains are left in the wave of the wave.
• Figure 3B This is identical to Figure 2, except the recovery is slower and the synaptic kinetics are faster so that re-excitation of the medium is prevented.
• Figure 4 Here the reversal potential of the synsapse is slowly changed in order to switch the medium from a slow rebound wave to a fast excitation front. The sign of the near shunting synapse changes from inhibition to excitation with only a few millivolts difference. A localized stimulus is given intermittently to excite the middle of the medium.