Fig. 2.

The effect of the mean and SD of the background current on the distribution of membrane potentials and on the accuracy of transmission. a, The probability distribution of membrane potentials of a neuron for the different propagation modes. Membrane potentials of a single neuron are collected for 2 sec while just the background current is applied; no stimulus is present. i, The probability distribution for synfire mode of Figure 1b. The narrow distribution favors synchronous firing. ii, The distribution for the rate mode (Fig. 1c). The distribution is wide, favoring asynchronous firing and a rapid response. iii, The distribution for the synchronized propagation mode of Figure 1d. iv, The distribution for the propagation mode of Figure 1e. For clarity, the distributions are scaled vertically. b, The dissimilarity between stimulus and the fifth layer response for varying background currents. A random stimulus current is injected into the first layer. The dissimilarity is measured by comparing the injected current with the network output (see Materials and Methods). In the rate mode, the response is most similar to the input. (The contour lines on the bottom plane denote 0.1 intervals starting at 0.2). c, The background firing rates for the different conditions. The background firing rate increases with increasing mean and increasing noise current. The threshold current is just above 100 pA. Contour lines denote 5 Hz intervals.