Neural basis of prosocial behavior

Abstract

The ability to behave in ways that benefit other individuals' well-being is among the most celebrated human characteristics crucial for social cohesiveness. Across mammalian species, animals display various forms of prosocial behaviors - comforting, helping, and resource sharing - to support others' emotions, goals, and/or material needs. In this review, we provide a cross-species view of the behavioral manifestations, proximate and ultimate drives, and neural mechanisms of prosocial behaviors. We summarize key findings from recent studies in humans and rodents that have shed light on the neural mechanisms underlying different processes essential for prosocial interactions, from perception and empathic sharing of others' states to prosocial decisions and actions.

Keywords: amygdala; anterior cingulate cortex; comforting; empathy; helping; neural circuit.

Figure 1.

Categorization of prosocial behaviors. (A) Diverse forms of social behaviors are distributed along two spectrums: whether they are affiliative or agonistic and whether they primarily serve to benefit the self or others (axis scales are arbitrary). Prosocial behavior represents a specific category of social behavior—it is not only affiliative but is also driven by the motivation of benefitting another and/or results in improvement of another’s welfare. (B) Prosocial behaviors can be broadly categorized based on the type of negative state or need that elicits them: (i) comforting – induced by others’ emotional distress; targeted helping – induced by others’ difficulty to complete a goal-related action; and (iii) sharing – induced by others’ material needs or desires.

Figure 2.

Different processes involved in prosocial interactions. Prosocial interaction is a multi-stage process that starts with the communication of others’ negative states or unmet needs through external cues (step 1). Perception of others’ states (step 2) can elicit empathic experience (step 3). Perception and sharing of others’ states motivate the observer to make prosocial decisions and issue prosocial interventions (step 4). This process involves evaluation and integration of self-, other-, and context-related information as well as self-regulation of emotions. Failure to regulate one’s own emotional response to others’ negative states may lead to excessive self-stress, which promotes self-protective behavior and reduces prosocial response (step 5). Helper’s prosocial interventions can lead to alleviation of the target’s negative state (step 6), which may then be signaled back to the helper (step 7). Prosocial behavior per se or the perceived improvement in others’ well-being is often associated with a rewarding experience to the helper (step 8).

Figure 3.

Main brain areas involved in prosocial decisions and actions in humans and rodents. (A) Prosocial decision making in humans has been shown to recruit brain areas involved in attribution of others’ emotional and mental states, evaluation of subjective values, norm representation and compliance, and reward processing. ACC, anterior cingulate cortex. MCC, midcingulate cortex. PCC, posterior cingulate cortex. AI, anterior insula. vmPFC, ventromedial prefrontal cortex. dmPFC, dorsomedial prefrontal cortex. dlPFC, dorsolateral prefrontal cortex, IPL, inferior parietal lobule. TPJ, temporoparietal junction. pSTS, posterior superior temporal sulcus. VTA, ventral tegmental area. (B) Brain areas shown to regulate prosocial behaviors in rodents. MeA, medial amygdala. MPOA, medial preoptic area. PVT, paraventricular nucleus of the thalamus. DRN, dorsal raphe nucleus. (C) Regulation of comforting behavior by the MeA-MPOA circuit in mice. In mice, olfactory cues play an important role in communicating emotional distress. Conspecific stress leads to activation of MeA neurons and MeA tachykinin (Tac1)-expressing GABAergic neurons (Tac1⁺/Vgat⁺ neurons), which promotes allogrooming behavior towards distressed partners through their projections to the MPOA, leading to a reduction of stress in the target [15].