Opioidergic regulation of emotional arousal: A combined PET–fMRI study

Tomi Karjalainen, Kerttu Seppälä, Enrico Glerean, Henry K. Karlsson, Juha Lahnakoski, Pirjo Nuutila, Iiro Jääskeläinen, Riitta Hari, Mikko Sams, Lauri Nummenmaa

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Emotions can be characterized by dimensions of arousal and valence (pleasantness). While the functional brain bases of emotional arousal and valence have been actively investigated, the neuromolecular underpinnings remain poorly understood. We tested whether the opioid and dopamine systems involved in reward and motivational processes would be associated with emotional arousal and valence. We used in vivo positron emission tomography to quantify μ-opioid receptor and type 2 dopamine receptor (MOR and D2R, respectively) availability in brains of 35 healthy adult females. During subsequent functional magnetic resonance imaging carried out to monitor hemodynamic activity, the subjects viewed movie scenes of varying emotional content. Arousal and valence were associated with hemodynamic activity in brain regions involved in emotional processing, including amygdala, thalamus, and superior temporal sulcus. Cerebral MOR availability correlated negatively with the hemodynamic responses to arousing scenes in amygdala, hippocampus,thalamus, and hypothalamus, whereas no positive correlations were observed in any brain region. D2R availability—here reliably quantified only in striatum—was not associated with either arousal or valence. These results suggest that emotional arousal is regulated by the MOR system, and that cerebral MOR availability influences brain activity elicited by arousing stimuli.
Original languageEnglish
Pages (from-to)4006–4016
Number of pages11
JournalCerebral Cortex
Issue number9
Early online date22 Nov 2018
Publication statusPublished - Sept 2019
MoE publication typeA1 Journal article-refereed


  • dopamine
  • fMRI
  • PET
  • neurotransmitters
  • receptor


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