The interaction between gaze and facial expression in the amygdala and extended amygdala is modulated by anxiety

The intranasal application of oxytocin (OT) has been shown to influence behavioral and neural correlates of social processing. These effects are probably mediated by genetic variations within the OT system. One potential candidate could be the CD38 gene, which codes for a transmembrane protein engaged in OT secretion processes. A common variation in this gene (rs3796863) was recently found to be associated with autism spectrum disorders (ASD). Using an imaging genetics approach, we studied differential effects of an intranasal OT application on neural processing of social stimuli in 55 healthy young men depending on their CD38 gene variant in a double-blind placebo-controlled crossover design. Genotype had a significant influence on both behavioral and neuronal measures of social processing. Homozygotic risk allele carriers showed slower reaction times (RT) and higher activation of left fusiform gyrus during visual processing of social stimuli. Under OT activation differences between genotypes were more evident (though not statistically significantly increased) and RT were accelerated in homozygotic risk allele carriers. According to our data, rs3796863 mainly influences fusiform gyrus activation, an area which has been widely discussed in ASD research. OT seems to modulate this effect by enhancing activation differences between allele groups, which suggests an interaction between genetic makeup and OT availability on fusiform gyrus activation. These results support recent approaches to apply OT as a pharmacological treatment of ASD symptoms.

Background: The judgment of the approachability of others based on their facial appearance often precedes social interaction. Whether we ultimately approach or avoid others may depend on such judgments. Method: We used functional magnetic resonance imaging to determine the neural basis for such approachability judgments and the relationship between these judgments and trait anxiety. Participants viewed ambiguous (i.e. neutral) or relatively unambiguous (i.e. angry, happy) faces, assessing either the approachability or the sex of the person depicted. Results: Neutral faces elicited more inconsistent responses within participants only during approachability judgment, suggesting ambiguous property as signals. The contrast pertaining to the interaction between task and face valence demonstrated activation in several areas, such that the left amygdala and medial, middle and inferior frontal gyri were responsive to angry faces when subjects were asked to recognize the sex (implicit task) and to neutral faces when required to discern the approachability (explicit task). Moreover, the blood oxygenation level-dependent change within the left amygdala in response to neutral faces during the judgment of approachability was positively correlated with participant trait anxiety. Conclusions: These findings extend a proposed model of social cognition by highlighting the functional engagement of the amygdala in approachability judgments, which underlie an individual's sensitivity to ambiguous sources of probable threat.

Sleep and emotion are closely linked, however the effects of sleep on socio-emotional task performance have only recently been investigated. Sleep loss and insomnia have been found to affect emotional reactivity and social functioning, although results, taken together, are somewhat contradictory. Here we review this advancing literature, aiming to 1) systematically review the relevant literature on sleep and socio-emotional functioning, with reference to the extant literature on emotion and social interactions, 2) summarize results and outline ways in which emotion, social interactions, and sleep may interact, and 3) suggest key limitations and future directions for this field. From the reviewed literature, sleep deprivation is associated with diminished emotional expressivity and impaired emotion recognition, and this has particular relevance for social interactions. Sleep deprivation also increases emotional reactivity; results which are most apparent with neuro-imaging studies investigating amygdala activity and its prefrontal regulation. Evidence of emotional dysregulation in insomnia and poor sleep has also been reported. In general, limitations of this literature include how performance measures are linked to self-reports, and how results are linked to socio-emotional functioning. We conclude by suggesting some possible future directions for this field.