Figure 1.

(Color online) Major discoveries mainly due to forward genetics. Major mutants and cloned genes related to behaviors are indicated for fruit fly, nematode, zebrafish, and mouse in chronological order. Several technical advances are also indicated. # indicates transcription factors. & indicates channels or transporters. Before 1990, however, the function of the gene was usually unknown at the time of gene identification. TTFL: transcription–translation feedback loop.