Modulating the activity of specific brain structures to understand function, but also to manage dysfunction, seems to be a timeless mission of neuroscientists. Classical tools are lesioning, electrical and chemical stimulation.

Although effective at the level of the brain structure, these tools lack a high degree of selectivity and specificity. In the search for more advanced neuromodulation techniques, for instance enabling one to influence only a specific subpopulation of neurons, optogenetic and Designer Receptors Exclusively Activated by Designer Drugs (DREADD) approaches have been introduced.