Fig. 9.

Information transmission through a two-site MWC molecule. The case of nACh receptors is illustrated for concreteness. (a) ACh (input) binds to ligand-gated ion channels (communication channel), thereby influencing the number of open ion channels (output). (b) The probability distribution of ACh concentration that maximizes the mutual information between input ([ACh]) and output (N_open) from Eq. (21). (c) The MWC ligand–receptor binding probabilities determine the conditional distribution of the total number of nACh receptors open as a function of ACh concentration, p(N_open|[ACh]) from Eq. (17), shown here as a heat map. (d) The probability distribution of N_open that maximizes the mutual information between input ([ACh]) and output (N_open). (b–d) Plots assume a total of 100 nACh receptors on the synaptic cleft for visualization purposes, although this underestimates the number of nACh receptors on a typical synaptic cleft and all plots use MWC parameters characteristic of nACh receptors.⁶⁸