Opioid Receptor PET Reveals the Psychobiologic Correlates of Reward Processing

Abstract

Little is known about the neurobiologic correlates of human personality. On the basis of the key role of the central opioidergic system in addiction and substance abuse, we investigated the relationship between certain personality traits that are supposed to be relevant in addiction and the opioid receptor status in healthy subjects. Methods: We investigated 23 healthy male volunteers who were extensively clinically tested to exclude substance abuse. All of the subjects underwent 1 PET scan with the subtype-nonselective opioidergic radioligand 18 F-fluoroethyldiprenorphine under resting conditions without sensory or cognitive stimulation. Subsequently, the subjects were psychologically tested for the personality traits novelty seeking, harm avoidance, reward dependence, and persistence, according to Cloninger's biosocial model of personality. The binding potential (BP) as a parameter of regional cerebral opioid receptor availability was computed by means of the modified Logan plot using the occipital cortex as a reference region. Further imaging data analysis was performed using statistical parametric mapping; after stereotactic normalization, the correlations were calculated between the regional BP and the psychologic scores on a voxel-by-voxel basis.Results: The correlation analysis between personality dimensions and opioid receptor availability showed a significant (P , 0.001) positive correlation between the scores of reward dependence and the BP of the bilateral ventral striatum with nucleus accumbens (z scores, 4.52 and 4.33, respectively). The additionally performed region-of-interest-based correlation analysis yielded correlation coefficients of r 5 0.84 and r 5 0.81 for the left and right ventral striata, respectively. No further significant correlations were detectable between the other personality dimensions and cerebral opioid receptor binding. Conclusion: In healthy subjects, personality traits, which might be predisposing for addictive behavior, are correlated to the opioidergic neurotransmission in core structures of the human reward system. Thebi ologic basis of human personality continues to be one of the most interesting and challenging issues of psychobiologic research. Different approaches have shown that certain personality traits are related to neurobiologic parameters (1,2). The development of dimensional models of personality enables a more appropriate description of the complexity and heterogeneity of personality; these models of personality might also be more closely related to the underlying neurobiologic substrate.One of the most popular models to describe human personality on a dimensional level is Cloninger's biosocial model of personality (3,4). This model comprises the 4 temperament dimensions novelty seeking, harm avoidance, reward dependence, and persistence and involves automatic, preconceptual responses to perceptual stimuli, most probably reflecting heritable biases in information processing. These dimensions are considered to be stable across time, except for novelty seeking...

The Anatomy of the Mesolimbic Reward System: A Link between Personality and the Placebo Analgesic Response

“…For example, the ventral striatum is also an important site of opioidergic neurotransmission, and conse- quently, the link between placebo analgesia and ventral striatum might be accounted for partly by interindividual differences in opioidergic function. Schreckenberger et al (2008) showed that opioid receptor binding potentials in the ventral striatum correlate with the trait of reward dependence. In contrast, they did not find a relationship between opioids and novelty seeking.…”

Positive Association Between Limbic Metabotropic Glutamate Receptor 5 Availability and Novelty-Seeking Temperament in Humans: An 18F-FPEB PET Study

“…In parallel, dysregulation or disequilibrium of brain neurotransmitters have repeatedly been linked to mental diseases. Therefore, a better understanding of neurotransmitter systems and their involvement in personality and behavior may subsequently pave the way for improved treatment strategies for a multitude of neuropsychiatric disorders.Though temperament research has mainly implicated central monoaminergic systems, mounting evidence points toward a more complex neurotransmitter interplay to account for the variation in human personality (5,6,8). Glutamate is the main excitatory neurotransmitter in the brain and is involved in numerous aspects of behavior and cognition.…”

“…Though temperament research has mainly implicated central monoaminergic systems, mounting evidence points toward a more complex neurotransmitter interplay to account for the variation in human personality (5,6,8). Glutamate is the main excitatory neurotransmitter in the brain and is involved in numerous aspects of behavior and cognition.…”

“…Subsequently, genetic determinants of receptor expression and neuronal function in the normal variation of human behavior have been validated (2). Several temperament and personality traits, including novelty seeking (NS), harm avoidance, and impulsivity, have been associated with the vulnerability to mental illnesses (3,4) and have been directly related to receptors and neurotransmission using functional imaging (5)(6)(7). In parallel, dysregulation or disequilibrium of brain neurotransmitters have repeatedly been linked to mental diseases.…”

Molecular imaging and neural networks in impulse control disorders in Parkinson's disease

“…As well, another important line of research is the opioid system and its relation to reward behaviour. Schreckenberger et al [34], using the opioidergic radioligand 18 F-fluoroethyl-diprenorphine, found a correlation between scores of reward dependence and binding potential in the ventral striatum and nucleus accumbens.…”