A new study by researchers at the Max Planck Institute for Brain Research uses computer simulations to explore how patterns of spikes propagate in neuronal networks constrained by experimental data from the turtle visual cortex. The researchers found that rare but strong connections in the network could promote the reliability of propagation, providing a substrate to easily halt or promote propagation, resulting in a highly reliable system to route activity within these networks. The research provides insight into how neurons in the brain communicate with one another and how this communication can be reliably controlled.