ABSTRACT
Preferences for different combinations of costs and benefits are a key source of variability in economic decision-making. However, the neurochemical basis of individual differences in these preferences is poorly understood. Studies in both animals and humans have demonstrated that direct manipulation of the neurotransmitter dopamine (DA) significantly impacts cost/benefit decision-making, but less is known about how naturally occurring variation in DA systems may relate to individual differences in economic behavior. In the present study, 25 healthy volunteers completed a dual-scan PET imaging protocol with [(18)F]fallypride and d-amphetamine to measure DA responsivity and separately completed the effort expenditure for rewards task, a behavioral measure of cost/benefit decision-making in humans. We found that individual differences in DA function in the left striatum and ventromedial prefrontal cortex were correlated with a willingness to expend greater effort for larger rewards, particularly when probability of reward receipt was low. Additionally, variability in DA responses in the bilateral insula was negatively correlated with willingness to expend effort for rewards, consistent with evidence implicating this region in the processing of response costs. These findings highlight the role of DA signaling in striatal, prefrontal, and insular regions as key neurochemical mechanisms underlying individual differences in cost/benefit decision-making.
Subject(s)
Brain/physiology , Decision Making/physiology , Dopamine/metabolism , Dopaminergic Neurons/metabolism , Reward , Adult , Cost-Benefit Analysis , Female , Humans , Male , Motivation , Young AdultABSTRACT
Dopamine (DA) has long been implicated in impulsivity, but the precise mechanisms linking human variability in DA signaling to differences in impulsive traits remain largely unknown. By using a dual-scan positron emission tomography approach in healthy human volunteers with amphetamine and the D2/D3 ligand [18F]fallypride, we found that higher levels of trait impulsivity were predicted by diminished midbrain D2/D3 autoreceptor binding and greater amphetamine-induced DA release in the striatum, which was in turn associated with stimulant craving. Path analysis confirmed that the impact of decreased midbrain D2/D3 autoreceptor availability on trait impulsivity is mediated in part through its effect on stimulated striatal DA release.
Subject(s)
Corpus Striatum/metabolism , Dextroamphetamine/administration & dosage , Dopamine/metabolism , Impulsive Behavior/metabolism , Receptors, Dopamine D3/metabolism , Tegmentum Mesencephali/metabolism , Adolescent , Adult , Amphetamine-Related Disorders/etiology , Amphetamine-Related Disorders/metabolism , Autoreceptors/metabolism , Benzamides/metabolism , Female , Humans , Ligands , Male , Positron-Emission Tomography , Pyrrolidines/metabolism , Receptors, Dopamine D2/metabolism , Signal Transduction , Substantia Nigra/metabolism , Ventral Tegmental Area/metabolism , Young AdultABSTRACT
Psychopathy is a personality disorder that is strongly linked to criminal behavior. Using [(18)F]fallypride positron emission tomography and blood oxygen level-dependent functional magnetic resonance imaging, we found that impulsive-antisocial psychopathic traits selectively predicted nucleus accumbens dopamine release and reward anticipation-related neural activity in response to pharmacological and monetary reinforcers, respectively. These findings suggest that neurochemical and neurophysiological hyper-reactivity of the dopaminergic reward system may comprise a neural substrate for impulsive-antisocial behavior and substance abuse in psychopathy.
Subject(s)
Antisocial Personality Disorder/metabolism , Antisocial Personality Disorder/psychology , Dopamine/metabolism , Nucleus Accumbens/metabolism , Receptors, Dopamine/metabolism , Reward , Adolescent , Adult , Brain Mapping/methods , Criminals/psychology , Female , Humans , Impulsive Behavior/metabolism , Impulsive Behavior/psychology , Limbic System/metabolism , Magnetic Resonance Imaging/methods , Male , Personality Assessment , Positron-Emission Tomography/methods , Single-Blind Method , Young AdultABSTRACT
BACKGROUND: Of the putative psychopathological endophenotypes in major depressive disorder (MDD), the anhedonic subtype is particularly well supported. Anhedonia is generally assumed to reflect aberrant motivation and reward responsivity. However, research has been limited by a lack of objective measures of reward motivation. We present the Effort-Expenditure for Rewards Task (EEfRT or "effort"), a novel behavioral paradigm as a means of exploring effort-based decision-making in humans. Using the EEfRT, we test the hypothesis that effort-based decision-making is related to trait anhedonia. METHODS/RESULTS: 61 undergraduate students participated in the experiment. Subjects completed self-report measures of mood and trait anhedonia, and completed the EEfRT. Across multiple analyses, we found a significant inverse relationship between anhedonia and willingness to expend effort for rewards. CONCLUSIONS: These findings suggest that anhedonia is specifically associated with decreased motivation for rewards, and provide initial validation for the EEfRT as a laboratory-based behavioral measure of reward motivation and effort-based decision-making in humans.
