text: Chemogenetics is the process by which macromolecules can be engineered to interact with previously unrecognized small molecules. Chemogenetics as a term was originally coined to describe the observed effects of mutations on chalcone isomerase activity on substrate specificities in the flowers of Dianthus caryophyllus. This method is very similar to optogenetics; however, it uses chemically engineered molecules and ligands instead of light and light-sensitive channels known as opsins.
  In recent research projects, chemogenetics has been widely used to understand the relationship between brain activity and behavior. Prior to chemogenetics, researchers used methods such as transcranial magnetic stimulation and deep brain stimulation to study the relationship between neuronal activity and behavior.