Figure 4.

Mutual information rate (lower bound) between the F signal (A,C, red) or D signal (B,D, green), and the output spike train when the modulation amplitude of the respective other signal (ϵ_D or ϵ_F) is varied. In the supra-threshold regime (I_i = −2.25 nA; A,B), a second signal always impedes the transmission of the first. In contrast, in the sub-threshold regime (I_i = −9.5625 nA; C,D), increasing the modulation amplitude of the D signal can be beneficial to the transmission of the F signal and vice versa. For both regimes, r_F = r_D = 20 Hz; ϵ_F = 0.05 in A,C; ϵ_D = 0.05 in B,D.