We examined the contribution of the nigrostriatal DA system to instrumental learning and behavior using optogenetics in awake. behaving mice. Using Cre-inducible channelrhodopsin-2 (ChR2) in mice expressing Cre recombinase driven by the tyrosine hydroxylase promoter (Th-Cre). we tested whether selective stimulation of DA neurons in the substantia nigra pars compacta (SNC). https://herbsdailyes.shop/product-category/vitamin-c/