L-dihydroxyphenylalanine that was restored under the influence of endogenous dopamine in DD mice changed mice behavior. They became hypoactive and hypophagic and could carry out complicated tasks that are impossible to implement without both activation and plasticity. "Additional goal of this study was to separate performance factors from cognitive processes as described by Denenberg, Kim and Palmiter (2004)2
It was rather difficult to design the experiments in a proper way because of some things. First, learning, liking and wanting are not alternative behaviors. Second, animals tend to be hypoactive and hyperphagic under the influence of dopamine.
Some hypotheses were posited. The one concerning hedonia assumes that "dopamine mediates the sensory pleasure of rewards, such as food"3 (Wise, 2004). The evidence was caused by the observation that dopamine leads to the growing reward consumption. The hypothesis about learning presumes that if we want to make animals associate rewards with special clues we must intake them dopamine. The last hypothesis in respect to wanting supposes that dopamine does not influence the interconnection liking-reward and learning- reward. ...Show more