  Many natural and artificial two-states signaling devices are connected
forming networks. The information-processing potential of these systems is
usually related to the response to weak external signals. Here, using a network
of overdamped bistable elements, we study the effect of a heterogeneous complex
topology on the signal response. The analysis of the problem in random
scale-free networks, reveals that heterogeneity plays a crucial role in
amplifying external signals. We have contrasted numerical simulations with
analytical calculations in simplified topologies.
