Serotonin 5-HTTLPR Genotype Modulates Reactive Visual Scanning of Social and Non-social Affective Stimuli in Young Children

Abstract

Previous studies have documented the 5-HTTLPR polymorphisms as genetic variants that are involved in serotonin availability and also associated with emotion regulation and facial emotion processing. In particular, neuroimaging and behavioral studies of healthy populations have produced evidence to suggest that carriers of the Short allele exhibit heightened neurophysiological and behavioral reactivity when processing aversive stimuli, particularly in brain regions involved in fear. However, an additional distinction has emerged in the field, which highlights particular types of fearful information, i.e., aversive information which involves a social component versus non-social aversive stimuli. Although processing of each of these stimulus types (social and non-social) is believed to involve a subcortical neural system which includes the amygdala, evidence also suggests that the amygdala itself may be particularly responsive to socially significant environmental information, potentially due to the critical relevance of social information for humans. Examining individual differences in neurotransmitter systems which operate within this subcortical network, and in particular the serotonin system, may be critically informative for furthering our understanding of the neurobiological mechanisms underlying responses to emotional and affective stimuli. In the present study we examine visual scanning patterns in response to both aversive and positive images of a social or non-social nature in relation to 5-HTTLPR genotypes, in 49 children aged 4-7 years. Results indicate that children with at least one Short 5-HTTLPR allele spent less time fixating the threat-related non-social stimuli, compared with participants with two copies of the Long allele. Interestingly, a separate set of analyses suggests that carriers of two copies of the short 5-HTTLPR allele also spent less time fixating both the negative and positive non-social stimuli. Together, these findings support the hypothesis that genetically mediated differences in serotonin availability mediate behavioral responses to different types of emotional stimuli in young children.

The 5-HTTLPR polymorphism impacts moral permissibility of impersonal harmful behaviors

“…The previous study indicated that the Caucasians with the SS genotype of 5-HTTLPR polymorphism rate impersonal harms as more impermissible (Marsh et al ., 2011), while we found that the Asians with the SS genotype rate impersonal harms as more permissible. For Caucasians, the enhancement of the S allele on permissibility rating may attribute to the allele’s roles in heightening the amygdala activation (Dannlowski et al ., 2010; Lonsdorf et al ., 2014; Cheon et al ., 2015; Kilpatrick et al ., 2015; Christou et al ., 2017). However, ethnic differences in the functions of S allele in amygdala activation should be noticed.…”

“…However, ethnic differences in the functions of S allele in amygdala activation should be noticed. For example, the S allele heightens the reactivity of the amygdala in Caucasians (Dannlowski et al ., 2010; Lonsdorf et al ., 2014; Cheon et al ., 2015; Kilpatrick et al ., 2015; Christou et al ., 2017), while this allele decreases the reactivity of the amygdala in Asians (Lee & Ham, 2008; Li et al ., 2012; Long et al ., 2014). These findings may suggest that Asians with the S allele may show lower emotional aversion to harms than Caucasians with this allele.…”

Interparental hostility and children’s externalizing symptoms: Attention to anger as a mediator.

“…Given the developmental constraints on coping efficacy, restricting attention to threatening stimuli is proposed to be one of the few viable strategies for managing heightened insecurity in early childhood (Bowlby, 1980; Bretherton & Munholland, 1999). For example, in a sample of 4- to 7-year-old children, Christou et al (2017) found that younger children exhibited greater attentional avoidance to negative stimuli. As adverse experiences become less overwhelming with development, it is possible that attentional avoidance to threats diminishes or even shifts toward sensitization as children age into adolescence (e.g., Gulley et al, 2014; Schermerhorn et al, 2015; Shackman et al, 2007).…”

“…This was followed by the appearance of the circular matrix of adult faces (i.e., 1 emotion face, 5 neutral faces) displayed for 3500 milliseconds. Stimulus presentations of similar duration have been successfully used in previous research with preschool and early elementary school children (e.g., Christou, Wallis, Blair, Zeegers, & McCleery, 2017; Gamble & Rapee, 2009). After five practice trials, 24 target trials were conducted, with each of the target emotions (i.e., anger, sadness, fear) displayed eight times in random order.…”