Novel approaches to understanding the social brain

In a symposium on elucidating social dysfunction, the social brain was approached from different disciplines. Findings were presented on the neural basis of helping behaviour under threat, and a novel model of social anxiety disorder (SAD) was proposed [1,2].

SAD is primarily characterised by intense fear and avoidance of various benign/common social situations. SAD is the third most common psychiatric disorder, with a lifetime prevalence of 12%. While highly common, there are few experimental models or specific treatments for the disorder.

Dr David Slattery (Goethe University, Germany) described a novel animal model that specifically induces social anxiety without potentially confounding alterations in other behavioural measures. In this Pavlovian social fear conditioning (SFC) model, mice were given an electric foot shock each time they investigated the social stimulus in front of them, an unfamiliar male mouse. SFC was found to be a useful model to study social fear. It induced both short-term and long-term specific fear of social stimuli, and this fear sensitised over time. The researchers then wanted to see whether oxytocin is a viable target for anxiety disorders. Neuropeptides, with discrete synthesis and receptor sites, emerge as viable candidates with a growing research focus on oxytocin. The results showed that oxytocin receptor expression increased but oxytocin release decreased in socially fearful mice. Administering oxytocin abolished social fear.

Dr Slattery explained that people with SAD have an altered microbiome. To explore causality in SAD, faecal microbiota transplantation (FMT) was used: human faecal microbiota were transplanted into mice. FMT did not affect baseline behaviour but potentiated the effect of SFC.

Helping behaviour has been observed in different species, especially mammals. This type of behaviour is especially puzzling when it occurs under threatening circumstances, according to Dr Joana Vieira (Karolinska Institute, Sweden). Helping under threat occurs in the presence of 2 salient cues: the distress of another individual and the threat. Little is known about the role of the observer’s own threat responses on helping behaviour: do they help or hinder other-oriented care? Dr Vieira and colleagues examined the impact of threat imminence on helping, both at a behavioural and a neural level. Healthy adults (n=98) made trial-by-trial decisions about whether to help a co-participant avoid an aversive shock at the risk of receiving a shock themselves. Helping decisions were prompted under imminent or distal threat. Regardless of how likely participants were to receive a shock themselves, they helped the co-participant more under imminent than under distal threat. Responses were faster and heart rate increased during imminent compared with distal threats.

Dr Vieira concluded that there are striking parallel responses to imminence of threats directed at oneself and others. Own responses to threatening events influence our decisions to help others under threat. Specifically, neural representation of the threat –and not the other’s distress– in key defensive regions like the amygdala guide helping. These findings may imply that defensive and altruistic tendencies may be convergent rather than conflicting. This has important implications for the way we regard interpersonal consequences of disorders of fear and anxiety and their treatment.

1. Slattery DA. Novel insights into social fear. S.14.02, ECNP 2021 Congress, 2–5 October.
2. Vieira JB. Neural basis of helping behaviour under threat. S.14.04, ECNP 2021 Congress, 2–5 October.

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Posted on 26 November, 2021