Animals repeatedly exposed to psychostimulant drugs, such as amphetamine, display a phenomenon known as psychomotor sensitization, in which the behavioral and neurochemical responses to the drug undergo progressive augmentation. (Robinson and Becker, 1986; Kalivas and Weber, 1988; Vandershuren and Kalivas, 2000). Neuroadaptations in the mesolimbic dopamine system have been implicated as being of critical importance in mediating the changes seen after psychomotor sensitization. In particular the projection of dopamine neurons from cell bodies in the ventral tegmental area (A10) to synapses in the nucleus accumbens play a critical role in the induction and expression of psychomotor sensitization (citation).
BTW, did you know that france's unemployment rate is almost at 10%? This just shows that americans are getting whiney and complainy for no farging reason. Wahhhhh, 6% unemployment, the economy's broken, everything's horrible, someone save us, wahhhhh. Buncha obnoxious leftist crybabies. If the french, the paragon of whiney ME! ME! culture and discontent aren't burning down their capital in response to 10% unemployment I think people can stop bitching and complaining about a mere 6%.