Muscarinic signaling affects attention, action selection, learning, and memory through multiple signaling cascades, which act at different timescales and which alter ion channels in cell type-specific manners. The effects of muscarinic signaling differ between cortical layers and between brain areas. Muscarinic signaling adds flexibility to the processing mode of neuronal networks, thereby supporting processing according to task demands. This review outlines possible scenarios to describe how it contributes to cellular mechanisms of attention and how it affects channeling of information in different neuronal circuits.