Figure 2.

Model CN afferent input and postsynaptic α-functions. A, PSTH of spike counts for 25 model CN Poisson neurons over 40 trials with a mean firing rate μ₀ of 400 Hz. The stimulus occurs from 0 to 20 ms. Each time bin is 1 ms and there are 25 × 40 = 1000 neuron trials per bin, so the spike count can be interpreted as an averaged, instantaneous firing rate in hertz. The onset burst in the CN neurons is easily seen in the first and second bins. B, The α-function of the model with τ_s = 0.7 ms (EPSP; solid line) and τ_s = 1.1 ms (IPSP; dashed line) plotted as a function of time since the postsynaptic neuron generated an action potential. A 1 ms delay was added to simulate the axonal delays of each neuron in the circuit. Each function is normalized to an area of 1 before being scaled by q to ensure the same total energy for each spike regardless of τ_s. Increased or decreased levels of current can be implemented by multiplying the α-functions by a scaling factor (connection weight).