Optogenetic mimicry of the transient activation of dopamine neurons by natural reward is sufficient for operant reinforcement.
Kim KM, Baratta MV, Yang A, Lee D, Boyden ES, Fiorillo CD. Optogenetic mimicry of the transient activation of dopamine neurons by natural reward is sufficient for operant reinforcement. PLoS One. 2012; 7(4):e33612.