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Background: Cross-species evidence suggests that genetic and experiential factors act early in development to establish individual emotional traits, but little is known about the mechanisms that emerge during this period to mediate long-term outcomes. Here, we tested the hypothesis that known genetic and environmental risk conditions may heighten infants' natural tendency to attend to threat-alerting stimuli, resulting in a cognitive bias that may contribute to emotional vulnerability. Methods: Data from two samples of 5-7-month-old infants (N = 139) were used to examine whether established candidate variations in the serotonin-system genes, i.e., TPH2 SNP rs4570625 (-703 G/T) and HTR1A SNP rs6295 (-1019 G/C), and early rearing condition (maternal stress and depressive symptoms) are associated with alterations in infants' attention to facial expressions. Infants were tested with a paradigm that assesses the ability to disengage attention from a centrally presented stimulus (a nonface control stimulus or a neutral, happy, or fearful facial expression) toward the location of a new stimulus in the visual periphery (a geometric shape). Results: TPH2 -703 T-carrier genotype (i.e., TT homozygotes and heterozygotes), presence of maternal stress and depressive symptoms, and a combination of the T-carrier genotype and maternal depressive symptoms were associated with a relatively greater difficulty disengaging attention from fearful facial expressions. No associations were found with infants' temperamental traits. Conclusions: Alterations in infants' natural attentional bias toward fearful facial expressions may emerge prior to the manifestation of emotional and social behaviors and provide a sensitive marker of early emotional development. [ABSTRACT FROM AUTHOR]

Background: Allelic variation in the promoter region of a gene that encodes tryptophan hydroxylase isoform 2 (TPH2), a rate-limiting enzyme of serotonin synthesis in the central nervous system, has been associated with variations in cognitive function and vulnerability to affective spectrum disorders. Little is known about the effects of this gene variant on cognition during development and about possible intermediate developmental steps that lead to the adult phenotype. Here, we examined the hypothesis that the TPH2 -703 may act during early stages of development and bias the acquisition of elementary cognitive processes involved in attention and emotion regulation. Methods: Seven-month-old infants ( n = 66) were genotyped for the TPH2 -703 G/T polymorphism ( rs4570625) and tested for the efficiency of attention shifts from a stimulus at fixation to a new stimulus in the visual periphery. Results: Compared to TPH2 G/G homozygotes, infants with the T-carrier genotype exhibited a significantly higher number of missing attention shifts. This genotype effect tended to be particularly pronounced when infants had to disengage from an affectively salient stimulus before shifting attention to the peripheral stimulus. The results also showed that TPH2 genotype was indirectly associated, via its effect on attention disengagement, with temperamental emotion regulation (soothability). Conclusions: Together, these results implicate serotonin system genes in early cognitive development and suggest variations in the early-emerging cognitive capacities as a potential developmental precursor of individual differences in emotion regulation and vulnerability to affective disorders. [ABSTRACT FROM AUTHOR]

Background: It is unclear why children with autism spectrum disorders (ASD) tend to be inattentive to, or even avoid eye contact. The goal of this study was to investigate affective-motivational brain responses to direct gaze in children with ASD. To this end, we combined two measurements: skin conductance responses (SCR), a robust arousal measure, and asymmetry in frontal electroencephalography (EEG) activity which is associated with motivational approach and avoidance tendencies. We also explored whether degree of eye openness and face familiarity modulated these responses. Methods: Skin conductance responses and frontal EEG activity were recorded from 14 children with ASD and 15 typically developing children whilst they looked at familiar and unfamiliar faces with eyes shut, normally open or wide-open. Stimuli were presented in such a way that they appeared to be looming towards the children. Results: In typically developing children, there were no significant differences in SCRs between the different eye conditions, whereas in the ASD group the SCRs were attenuated to faces with closed eyes and increased as a function of the degree of eye openness. In both groups, familiar faces elicited marginally greater SCRs than unfamiliar faces. In typically developing children, normally open eyes elicited greater relative left-sided frontal EEG activity (associated with motivational approach) than shut eyes and wide-open eyes. In the ASD group, there were no significant differences between the gaze conditions in frontal EEG activity. Conclusions: Collectively, the results replicate previous finding in showing atypical modulation of arousal in response to direct gaze in children with ASD but do not support the assumption that this response is associated with an avoidant motivational tendency. Instead, children with ASD may lack normative approach-related motivational response to eye contact. [ABSTRACT FROM AUTHOR]