The causal role of the somatosensory cortex in prosocial behaviour

Abstract

Witnessing another person’s suffering elicits vicarious brain activity in areas that are active when we ourselves are in pain. Whether this activity influences prosocial behavior remains the subject of debate. Here participants witnessed a confederate express pain through a reaction of the swatted hand or through a facial expression, and could decide to reduce that pain by donating money. Participants donate more money on trials in which the confederate expressed more pain. Electroencephalography shows that activity of the somatosensory cortex I (SI) hand region explains variance in donation. Transcranial magnetic stimulation (TMS) shows that altering this activity interferes with the pain–donation coupling only when pain is expressed by the hand. High-definition transcranial direct current stimulation (HD-tDCS) shows that altering SI activity also interferes with pain perception. These experiments show that vicarious somatosensory activations contribute to prosocial decision-making and suggest that they do so by helping to transform observed reactions of affected body-parts into accurate perceptions of pain that are necessary for decision-making.

Predicting Empathy from Resting Brain Connectivity

“…As for (II), empathic concern was predicted by the within-network connectivity of the somatomotor network. This result further supports an embodied, somatomotor foundation for our concern for others' welfare, in line with numerous findings relating vicarious somatosensory activation to multiple forms of prosocial behavior ((nonstrategic generosity in economic games: Christov-Moore and Iacoboni, 2016;harm aversion in moral dilemmas: Christov-Moore et al, 2017b; donations to reduce pain in another: Gallo et al, 2018;helping behavior: Hein et al, 2011;Morelli et al, 2014;charitable donations: Ma et al, 2011). This also agrees with our recent finding that inferior premotor activation during observation of pain in others was predictive of participants' later tendency to avoid inflicting harm in hypothetical moral dilemmas (Christov-Moore et al, 2017b).…”

“…The most likely neural substrate for resonance appears to be "neural resonance" (Zaki and Ochsner, 2012), the phenomenon of shared neural representations for the perception and experience of disgust (Jabbi et al, 2011;Wicker et al, 2003), somatosensation (Bufalari et al, 2007;Masten et al, 2011;Singer et al, 2006), emotion (Carr et al, 2003;Pfeifer et al, 2008) and motor behavior (Iacoboni, 2009;Keysers and Fadiga, 2008). Not surprisingly, neural resonance has been repeatedly associated with self-reported measures of trait empathy (Avenanti et al, 2009;Jabbi et al, 2011;Pfeifer et al, 2008) and is predictive of pro-social behavior (non-strategic generosity in economic games: Christov-Moore and Iacoboni, 2016; harm aversion in moral dilemmas: Christov-Moore et al, 2017b; donations to reduce pain in another: Gallo et al, 2018;helping behavior: Hein et al, 2011;Morelli et al, 2014;charitable donations: Ma et al, 2011), suggesting that our resonance with others may underlie our empathic concern (and hence prosocial inclinations) for others.…”

“…Following work on restingstate and empathy (e.g. Cox et al, 2012), in a more exploratory fashion, we hypothesized that resting connectivity patterns within and between other cortical networks could also predict levels of trait empathy, with particular attention to the somatomotor network, which has been linked to many forms of prosociality (nonstrategic generosity in economic games: Christov-Moore and Iacoboni, 2016; harm aversion in moral dilemmas: Christov-Moore et al, 2017b; donations to reduce pain in another: Gallo et al, 2018;helping behavior: Hein et al, 2011;Morelli et al, 2014;charitable donations: Ma et al, 2011).…”

Neuro-computational mechanisms of action-outcome learning under moral conflict

“…We often have to learn that certain actions lead to favorable outcomes for us, but harm others, while alternative actions are less favorable for us but avoid or mitigate harms to others 1 . Much is already known about the brain structures involved in making moral choices when the relevant action-outcome contingencies are well known [2][3][4][5][6][7][8][9] , but how we learn these contingencies remains poorly understood, especially in situations pitting gains to self against losses for others.…”

“…Or do we typically track separate expectations for benefits to the self and harms to others? In addition, people differ in how they represent benefits and harms to self 14 , and in whether they prefer to maximize benefits for the self vs. minimizing harms to others 3,4,6 . How can such differences be computationally represented using RLT?…”