Network stability during ongoing synaptic plasticity depends crucially on the homeostatic time constant.

<p>(<b>A</b>) Temporal evolution of the average firing rate in the excitatory population for different homeostatic time constants . Explosion of firing rate indicated by dashed lines. Curves for (dark blue), (light blue), and (turquoise) overlap on the interval from 2 h to 24 h indicating stability. With (black) we show one of the cases with very short where the activity spontaneously dies. (<b>B</b>) Spike raster of 200 randomly selected excitatory neurons. The last two seconds are shown before the network activity destabilizes (). (<b>C</b>) For , the activity stays asynchronous and irregular even after 24 h hours of simulated time. (<b>D</b>) Firing statistics in a stable network () measured after 24 h of simulated time. Histogram of single neuron firing rates (blue) and coefficient of variation (CV ISI, red) across neurons and the ISI distribution of all neurons (yellow). Arrowheads indicate mean values. Black lines represent the corresponding statistics prior to any synaptic modifications (copied from <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003330#pcbi-1003330-g001" target="_blank">Figure 1</a>). (<b>E</b>) Population firing rate for stable simulation runs at as a function of the homeostatic time constant. The dashed line indicates the target firing rate . (<b>F</b>) Evolution of the synaptic weight distribution during the first 8 hours of synaptic plasticity ().