Activity of individual neurons with adaptation or synaptic filtering.

A: Firing rate response of two different neurons with adaptation (red curves) and two different neurons with synaptic filtering (grey curves) to the same time-varying input (black curve). B: Normalized linear filters for the neurons shown in A. C: Timescales of the linear filter for neurons with adaptation (red lines) and for neurons with synaptic filtering (grey lines) as a function of the timescale τw or τs, respectively. The dashed lines indicate the effective timescale of the evoked activity obtained by weighing each individual timescale with its amplitude in the linear filter. The effective timescale for neurons with adaptation saturates for large adaptation time constants, while it grows proportionally to the synaptic time constant for neurons with synaptic filtering. Note that for the adaptive neuron, if the two eigenvalues are complex conjugate, there is only one decay timescale. The triangles on the temporal axis indicate the time constants used in A and B. Adaptation coupling gw = 5. D: Variance of the input current as a function of the slow time constant when the adaptive and synaptic neurons are stimulated with Gaussian white noise of unit variance. In the case of neurons with adaptation, two different values of the adaptation coupling gw are shown. Time in units of the membrane time constant τm.