Dopaminergic correlates of unexpected gains or losses in reward value
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چکیده
Successive negative and positive contrast occurs when the incentive value of a rewarding stimulus is devalued or increased unexpectedly and has been observed in many species ranging from bumble bee to man [1]. In two separate studies, we employed brain dialysis to monitor changes in dopamine (DA) efflux in the Nucleus Accumbens (NAc) of the rat during both negative and positive contrast as evidenced by significant reductions in lick rate when rats were switched unexpectedly from a 32% to 4% sucrose solution, or conversely a significant increase in lick rate following a switch from 4% to 32% relative to controls maintained on a 32% sucrose solution. During successive negative contrast we observed a significant reduction in the magnitude of DA efflux in the NAc [2], whereas positive contrast was accompanied by a significant increase in DA efflux [3].
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