Palmiter’s mice may just be extremely lazy. So lazy, in fact, that even taking a few steps across the cage to eat and drink aren’t worth the effort. How do we know? Because Salamone’s research shows that dopamine plays a key role in motivation. When he reduces dopamine signaling in the ventral striatum of rodents, they become less willing to work for a reward. They choose easy options over hard options, even if the hard option has a much larger payoff and would normally be the better choice. In other words, reducing their dopamine signaling makes them lazy. Palmiter’s mice have no dopamine,
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laziness equal dopamine deficient equals too high threshold for new action program.
