## < spike_gen >

Thespike_genobject defines a method of generating spikes. The input to the spike generator differs across models, but includes at least one time varying function that, after appropriate scaling and truncation, is used to drive the spike generation. The examples below demonstrate different spike generation methods. Some models may not allow all types of spike generation.

## poisson

Spikes are generated according to a time-varying mean rate. The rate is determined by taking the output from the previous stage of the model and adding 'offset0', multiplying by 'scale' and adding 'offset'. The resulting rate is half-wave rectified (i.e., values less than zero are set to zero). Spikes are generated randomly according to this rate, and 'toffset' is added to the spike times.<spike_gen> type poisson # Spike generation algorithm offset0 0.0 # Added *before* scaling [0.0] scale 1.0 # Multiplying factor [1.0] offset 0.0 # Added *after* scaling [0.0] toffset 0.040 # (s) Time offset (delay) added to spikes [0.0] # The following parameters allow a refractory period. However, it should # be noted that adding the refractory period will distort the shape of # the actual mean rate. The refractory period is implemented in a constant # rate Poisson process, and this process is then time-warped to create # the inhomogeneous process, but the refractory period is not taken into # account with the time warping. # After each spike, a duration is chosen from a Gaussian distribution for # the refractory period. Negative values are discaarded, and the first # non-negative value is taken. refract_mean 0.006 # (s) Mean of Gaussian duration refractory period refract_sd 0.002 # (s) SD of refractory period </spike_gen>## ifc

Conductance-driven integrate and fire spike generation.<spike_gen> type ifc # Spike generation algorithm v_spike 10.0 # (mV) Spike height v_th_x -52.5 # (mV) Spike threshold v_reset_x -57.8 # (mV) Spike reset voltage tau_r_ad 1.00 # (ms) Adaptation rise time tau_f_ad 80.0 # (ms) Adaptation fall time gbar_ad 0.0 # (nS) Adaptation conductance v_ex 0.0 # (mV) Excitatory reversal potential v_in -70.0 # (mV) Inhibitory reversal potential v_ad -90.0 # (mV) Adaptation reversal potential v_leak_x -81.6 # (mV) Leakage reversal potential g_leak_x 18.0 # (nS) Leakage conductance c_x 214.0 # (pF) Membrane capacitance trefr_x 1.5 # (ms) Refractory period gx_scale 2.0 # ( ) Scale excitatory g, before adding bias gx_bias 0.0 # (nS) Constant added to g, after any scaling# Membrane conductance noise type gfg # gfg = Gaussian filtered Gaussian noise mean 0.0 (nS) # mean sd 4.0 (nS) # standard deviation tsd 2.0 (ms) # temporal SD <> grect 1 # half-wave rectify gx, gi after adding noise </spike_gen>

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