Science posts

See science posts on page 25 below.

    • 1998
    • Alan Breier et al.
    • Dopamine D2 Receptor Density and Personal Detachment in Healthy Subjects
    • Objective:The purpose of this study was to examine the relationship between the personality trait involving personal detachment and dopamine D2 receptor specific binding in healthy subjects.Method:Eighteen adult subjects completed the Karolinska Scales of Personality and the Tridimensional Personality Questionnaire and participated in a study that used [11C]raclopride positron emission tomography (PET) to quantify striatal D2 receptor binding. Results:A significant relationship was found between D2 receptor specific binding and detachment scores on the Karolinska Scales of Personality but not between D2 receptor specific binding and attachment scores on the Tridimensional Personality Questionnaire. In an exploratory analysis, the authors found a significant relationship between binding and the sentimentality cluster on the Tridimensional Personality Questionnaire but on no other personality clusters scores on the Tridimensional Personality Questionnaire or Karolinska Scales of Person..
    • 2011
    • Tim Hahn et al.
    • Association between reward-related activation in the ventral striatum and trait reward sensitivity is moderated by dopamine transporter genotype
    • The impact of individual differences on human reward processing has been a focus of research in recent years, particularly, as they are associated with a variety of neuropsychiatric diseases including addiction and attention-deficit/hyperactivity disorder. Studies exploring the neural basis of individual differences in reward sensitivity have consistently implicated the ventral striatum (VS) as a core component of the human reward system. However, the mechanisms of dopaminergic neurotransmission underlying ventral striatal activation as well as trait reward sensitivity remain speculative. We addressed this issue by investigating the triadic interplay between VS reactivity during reward anticipation using functional magnetic resonance imaging, trait reward sensitivity, and dopamine (DA) transporter genotype (40-bp 3′VNTR of DAT, SLC6A3) affecting synaptic DA neurotransmission. Our results show that DAT variation moderates the association between VS-reactivity and trait reward se..
    • 2011
    • Yuliya S Nikolova et al.
    • Multilocus Genetic Profile for Dopamine Signaling Predicts Ventral Striatum Reactivity
    • Research integrating neuroimaging and molecular genetics has yielded important insights into how variability in brain chemistry predicts individual differences in brain function, behavior and related risk for psychopathology. However, existing studies have been limited by their focus on the independent effects of single polymorphisms with modest impact on brain chemistry. Here, we explored the effects of five functional polymorphisms affecting dopamine (DA) signaling on reward-related ventral striatum (VS) reactivity, measured with BOLD fMRI, in a sample of 69 Caucasians. We also compiled individual multilocus genetic profile scores reflecting the additive effects of alleles conferring relatively increased DA signaling across the five polymorphic loci: DAT1 9-repeat, DRD4 7-repeat, DRD2 -141C Del, DRD2 Taq1A C (A2), and COMT 158Met. These multilocus DA profile scores accounted for 10.9% of the inter-individual variability in reward-related VS reactivity. In contrast, none of the indi..
    • 2006
    • Ahmad R. Hariri et al.
    • Preference for Immediate over Delayed Rewards Is Associated with Magnitude of Ventral Striatal Activity
    • Discounting future outcomes as a function of their deferred availability underlies much of human decision making. Discounting, or preference for immediate over delayed rewards of larger value, is often associated with impulsivity and is a risk factor for addictive disorders such as pathological gambling, cigarette smoking, and drug and alcohol abuse. The ventral striatum (VS) is involved in mediating behavioral responses and physiological states associated with reward, and dysregulation of the VS contributes to addiction, perhaps by affecting impulsive decision-making. Behavioral tests of delay discounting (DD), which index preference for smaller immediate over larger delayed rewards, covary with impulsive tendencies in humans. In the current study, we examined the relationship between individual differences in DD, measured in a behavioral assessment, and VS activity measured with blood oxygenation level-dependent functional magnetic resonance imaging, in 45 adult volunteers. VS acti..
    • 2008
    • Bj√∂rn H. Schott et al.
    • Mesolimbic Functional Magnetic Resonance Imaging Activations during Reward Anticipation Correlate with Reward-Related Ventral Striatal Dopamine Release
    • The dopaminergic mechanisms that control reward-motivated behavior are the subject of intense study, but it is yet unclear how, in humans, neural activity in mesolimbic reward-circuitry and its functional neuroimaging correlates are related to dopamine release. To address this question, we obtained functional magnetic resonance imaging (fMRI) measures of reward-related neural activity and [11C]raclopride positron emission tomography measures of dopamine release in the same human participants, while they performed a delayed monetary incentive task. Across the cohort, a positive correlation emerged between neural activity of the substantia nigra/ventral tegmental area (SN/VTA), the main origin of dopaminergic neurotransmission, during reward anticipation and reward-related [11C]raclopride displacement as an index of dopamine release in the ventral striatum, major target of SN/VTA dopamine neurons. Neural activity in the ventral striatum/nucleus accumbens itself also correlated with ven..
    • 2000
    • Kestler, Lisa Picken et al.
    • The Relation Between Dopamine D2 Receptor Density and Personality: Preliminary Evidence From the NEO Personality Inventory-Revised.
    • Objective: To examine the relation between dopamine (DA) D2 receptor-specific binding and personality, we assessed the relation between DA D2 binding and the NEO Personality Inventory-Revised (NEO PI-R). Background: Previous studies have demonstrated a relation between DA D2 receptor-specific binding and a personality trait involving personal detachment as defined by the Karolinska Scales of Personality. A subsequent study using a different measure of personal detachment failed to replicate this finding, suggesting that metric properties of the personality scale may be important. To further examine this issue, we assessed the relation between DA D2 binding and a third personality measure, the NEO PI-R. Methods: Eighteen adult subjects completed the NEO PI-R and participated in an 11C-raclopride positron emission tomography study to quantify striatal DA D2 receptor binding. Results: We did not find a significant relation between binding and detachment-like traits on the NEO P..
    • 2001
    • Tetsuya Suhara et al.
    • Dopamine D2 Receptors in the Insular Cortex and the Personality Trait of Novelty Seeking
    • Human personality has been considered to have a neurochemical background. We examined the relation between extrastriatal dopamine D2 receptor binding in living human brain and the personality trait of novelty seeking that has been proposed to be related to dopaminergic function in the brain. We measured extrastriatal dopamine D2 receptors of 24 healthy young male subjects using [11C]FLB 457 positron emission tomography. The personality trait of each subject was assessed by the Temperament and Character Inventory (TCI). Correlation of dopamine D2 receptor binding with novelty seeking was calculated using region-of-interest analysis and statistical parametric mapping based on the binding potential images generated using a reference tissue model. A significant negative correlation was observed between binding potential values and the novelty seeking scores on TCI in the right insular cortex. No significant correlation was observed in any other region. Our result indicates that there is ..
    • 2014
    • Sylvia M.L. Cox et al.
    • Striatal D1 and D2 signaling differentially predict learning from positive and negative outcomes
    • The extent to which we learn from positive and negative outcomes of decisions is modulated by the neurotransmitter dopamine. Dopamine neurons burst fire in response to unexpected rewards and pause following negative outcomes. This dual signaling mechanism is hypothesized to drive both approach and avoidance behavior. Here we test a prediction deriving from a computational reinforcement learning model, in which approach is mediated via activation of the direct cortico-striatal pathway due to striatal D1 receptor stimulation, while avoidance occurs via disinhibition of indirect pathway striatal neurons secondary to a reduction of D2 receptor stimulation. Using positron emission tomography with two separate radioligands, we demonstrate that individual differences in human approach and avoidance learning are predicted by variability in striatal D1 and D2 receptor binding, respectively. Moreover, transient dopamine precursor depletion improved learning from negative outcomes. These findin..
    • 2010
    • Albert Gjedde et al.
    • Inverted-U-shaped correlation between dopamine receptor availability in striatum and sensation seeking
    • Sensation seeking is a core personality trait that declines with age in both men and women, as do also both density and availability of the dopamine D2/3 receptors in striatum and cortical regions. In contrast, novelty seeking at a given age relates inversely to dopamine receptor availability. The simplest explanation of these findings is an inverted-U-shaped correlation between ratings of sensation seeking on the Zuckerman scale and dopamine D2/3 receptor availability. To test the claim of an inverted-U-shaped relation between ratings of the sensation-seeking personality and measures of dopamine receptor availability, we used PET to record [11C]raclopride binding in striatum of 18 healthy men. Here we report that an inverted-U shape significantly matched the receptor availability as a function of the Zuckerman score, with maximum binding potentials observed in the midrange of the scale. The inverted-U shape is consistent with a negative correlation between sensation seeking and the ..
    • 2005
    • Frank, M
    • Dynamic Dopamine Modulation in the Basal Ganglia: A Neurocomputational Account of Cognitive Deficits in Medicated and Nonmedicated Parkinsonism
    • Dopamine (DA) depletion in the basal ganglia (BG) of Parkinson's patients gives rise to both frontal-like and implicit learning impairments. Dopaminergic medication alleviates some cognitive deficits but impairs those that depend on intact areas of the BG, apparently due to DA “overdose.” These findings are difficult to accommodate with verbal theories of BG/DA function, owing to complexity of system dynamics: DA dynamically modulates function in the BG, which is itself a modulatory system. This article presents a neural network model that instantiates key biological properties and provides insight into the underlying role of DA in the BG during learning and execution of cognitive tasks. Specifically, the BG modulates the execution of “actions” (e.g., motor responses and working memory updating) being considered in different parts of the frontal cortex. Phasic changes in DA, which occur during error feedback, dynamically modulate the BG threshold for facilitat..