Modern medical diagnostics and brain research would be unthinkable without magnetic resonance imaging (MRI). In addition to traditional imaging, which reveals anatomical structures, functional MRI (fMRI) has become a valuable tool. It comes close to allowing us to watch the brain at work and has contributed considerably to the advances in human cognitive neuroscience. However, fMRI is an indirect method, as it measures a surrogate signal, based on hemodynamics. Smart contrast agents (SCAs) shall overcome this limitation and allow a direct access to neuronal activity.