In most cases you will want to give some external input. Auryn has multiple classes which allow you to give spiking or current input to your neurons in a network. The most simple form of external input comes in the form of a homogeneous population of Poisson neurons which fire at constant rate PoissonGroup. If you want the input population to have a spatial firing rate profile instead use ProfilePoissonGroup. To give Poisson input with temporally varying firing rates use FileModulatedPoissonGroup. The latter will read the firing rates from a time series file (tiser) which you supply in text format. Finally if you want to stimulate your network with time varying Poisson input from multiple sub-populations within the external Poisson neuron population StimulusGroup might be right pick for you. If you want more control just create a ras file in your favourite programming language (e.g. Python) and simply load it into the Auryn simulation from an external file using FileInputGroup. If that's not enough you can write highly specific input groups for different purposes; see for instance AuditoryBeepGroup for an example.