Behavioural activation system sensitivity is associated with cerebral μ-opioid receptor availability

Area of Science:

• Neuroscience
• Psychology
• Neuroimaging

Background:

• Reinforcement-sensitivity theory posits that behavioral activation (BAS) and inhibition (BIS) systems drive approach and avoidance.
• Individual differences in BAS/BIS activity are thought to underlie variations in behavioral responses to rewards and punishments.
• The neurochemical underpinnings of BAS and BIS remain largely unclear.

Purpose of the Study:

• To investigate the neurochemical basis of the behavioral activation system (BAS) and behavioral inhibition system (BIS).
• To examine the association between mu-opioid receptor (MOR) availability and individual differences in BAS and BIS sensitivities.

Main Methods:

• Utilized in vivo positron emission tomography (PET) with [(11)C]carfentanil, a specific mu-opioid receptor (MOR) ligand.
• Scanned 49 healthy participants to measure MOR availability in the brain.
• Assessed individual BAS and BIS sensitivities using the BIS/BAS scales questionnaire.

Main Results:

• A positive association was found between BAS sensitivity and MOR availability in several brain regions, including the frontal cortex, amygdala, ventral striatum, brainstem, cingulate cortex, and insula.
• No significant association was observed between BIS sensitivity and MOR availability.
• The BAS subscale 'Fun Seeking' showed the strongest positive correlation with MOR availability.

Conclusions:

• The endogenous opioid system, specifically mu-opioid receptors, appears to underlie the behavioral activation system (BAS).
• Inter-individual differences in MOR availability may explain variations in reward-seeking behavior.
• This study provides novel neurochemical insights into the biological basis of personality traits related to reward sensitivity.