Endogenous opioid receptor system mediates costly altruism in the human brain
Poster No:
2440
Submission Type:
Abstract Submission
Authors:
Jinglu Chen1, Vesa Putkinen1, Kerttu Seppälä1, Jussi Hirvonen1, Kalliopi Ioumpa2, Valeria Gazzola2, Christian Keysers2, Lauri Nummenmaa1
Institutions:
1Turku PET Centre, Turku, Finland, 2The Netherlands Institute for Neuroscience, KNAW research institute, Amsterdam, The Netherlands
First Author:
Co-Author(s):
Kalliopi Ioumpa
The Netherlands Institute for Neuroscience, KNAW research institute
Amsterdam, The Netherlands
The Netherlands Institute for Neuroscience, KNAW research institute
Amsterdam, The Netherlands
Valeria Gazzola
The Netherlands Institute for Neuroscience, KNAW research institute
Amsterdam, The Netherlands
The Netherlands Institute for Neuroscience, KNAW research institute
Amsterdam, The Netherlands
Christian Keysers
The Netherlands Institute for Neuroscience, KNAW research institute
Amsterdam, The Netherlands
The Netherlands Institute for Neuroscience, KNAW research institute
Amsterdam, The Netherlands
Introduction:
Prosocial behavior is prevalent in humans and animals. It benefits the receiver, but also has a range of positive outcomes for the helper (De Waal & Preston, 2017). The neurocognitive link between empathy and prosociality has been investigated by quantifying responses in brain regions associated with empathy while witnessing the pain of others, and correlating these measures with individual differences in helping. However, the neuromolecular basis of individual differences in vicarious pain and helping remain poorly understood. PET studies showed that mu-opioid receptor (MOR) availability is negatively associated with haemodynamic responses to seeing others in pain (Karjalainen et al., 2017), and positively correlated with prosocial motivation as indexed by social attachment styles (Nummenmaa et al., 2015; Turtonen et al., 2021). Against this background, here we investigated whether individual differences in the MOR availability translate into measurable differences in the willingness to forfeit money to reduce pain to others.
Methods:
30 women particate in the fMRI experiment and 14 of them in the PET scan. MOR density was measured with high-affinity agonist radioligand [11C]carfentanil during resting baseline with PET/CT. The fMRI study was run using the costly helping paradigm (Gallo et al., 2018). Participants met the confederate and were explained that the experiment would be performed in two separate rooms connected by a video camera. During the scan, participants, believing to witness the pain of the victim through a closed-circuit television, actually viewed pre-recorded videos of the confederate receiving the painful simulation. On each trial, subjects first saw a video of the confederate receiving a painful electric shock (1st video). The intensity of expressed pain ranged randomly from 2 (mild pain) to 6 (moderate pain) out of ten. After the video, subjects could decide how much money they were willing to donate on that trial to reduce the intensity of the second shock (2nd video) in that trial (Figure 1).
FMRI data were analyzed in SPM12. First-level general linear models (GLM) were estimated by modeling the 1st video, donation phase, and the 2nd video by using boxcar regressors in the design matrix. Donation size (trial-wise donations for each subject) was entered as parametric modulator for the 1st video. Subject-wise contrast images were then generated for main effects of 1st video, donation phase, 2nd video.
For PET baseline data, radiotracer binding was quantified using non-displaceable binding potential (BPND), calculated as the ratio of specific binding to non-displaceable binding in the tissue.
To characterize the interactions between MOR availability and BOLD responses in pain perception and costly altruism, we first used PCA to reduce the dimensionality in the BPNDs across our ROIs, then used the first PC to predict the voxel-wise BOLD responses to the 1st video with donation size as a parametric modulator.
FMRI data were analyzed in SPM12. First-level general linear models (GLM) were estimated by modeling the 1st video, donation phase, and the 2nd video by using boxcar regressors in the design matrix. Donation size (trial-wise donations for each subject) was entered as parametric modulator for the 1st video. Subject-wise contrast images were then generated for main effects of 1st video, donation phase, 2nd video.
For PET baseline data, radiotracer binding was quantified using non-displaceable binding potential (BPND), calculated as the ratio of specific binding to non-displaceable binding in the tissue.
To characterize the interactions between MOR availability and BOLD responses in pain perception and costly altruism, we first used PCA to reduce the dimensionality in the BPNDs across our ROIs, then used the first PC to predict the voxel-wise BOLD responses to the 1st video with donation size as a parametric modulator.
Results:
People were in general willing to engage in costly helping, and donations increased as a function of the shock intensity shown in the first video, ß = 0.877, SE = 0.023, t = 37.591, p < 0.001. Haemodynamic activity in amydala, anterior insula, anterior cingulate cortex, striatum, primary motor cortex, primary somatosensory cortex, and thalamus increased when participants witnessed the pain of others. Insula, anterior cingulate cortex activated more strongly as the donation increased. These haemodynamic responses were negatively associated with MORs availability in the striatolimbic and cortical emotion circuits (Figure 2). In turn, haemodynamic responses during helping were positively associated with MOR availability in the anterior cingulate cortex and hippocampus.
Conclusions:
Taken together, these results suggest that the opioid system is intimately involved in vicarious pain and neural processing of helping decisions.
Novel Imaging Acquisition Methods:
PET 1
Perception, Attention and Motor Behavior:
Perception: Pain and Visceral 2
Keywords:
FUNCTIONAL MRI
Pain
Positron Emission Tomography (PET)
Other - helping, opioids
1|2Indicates the priority used for review
Provide references using author date format
Karjalainen, T., Karlsson, H. K., Lahnakoski, J. M., Glerean, E., Nuutila, P., Jääskeläinen, I. P., Hari, R., Sams, M., & Nummenmaa, L. (2017). 'Dissociable roles of cerebral μ-opioid and type 2 dopamine receptors in vicarious pain: A combined PET-fMRI study'. Cerebral Cortex, vol. 27, no. 8, pp. 4257–4266
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