Early event-related potentials to emotional faces differ for adults with autism spectrum disorder and by serotonin transporter genotype

Abstract

Objective To test differences in neural sensitivity to facial expressions, including expressions with open versus closed mouths, exhibited by (1) adults with autism spectrum disorder (ASD) compared to neurotypical adults, and by (2) short versus long serotonin transporter allele (SLC6A4) carriers. Methods Event related potentials (ERPs) to happy, fearful, and neutral expressions were collected from neurotypical adults (n = 25) and adults with ASD (n = 27)–of whom 32 had short and 13 had homozygous long SLC6A4 alleles. Results In the neurotypical group, we confirmed that the N170, VPP and EPN, but not the P1, were influenced by emotional expressions, and determined the EPN was the earliest component modulated by open mouth. Compared to the neurotypical group, individuals with ASD exhibited differences in EPN amplitude in response to open versus closed mouths and in hemispheric distribution. Across groups, short serotonin transporter allele carriers had reduced P1 amplitude compared to long allele carriers. Conclusions Individuals with ASD exhibited a different pattern of neural response when encoding and recognizing facial expressions at the EPN component. Across groups, SLC6A4 allele type modulated early sensory attention at the P1. Significance These results provide insight into the nature of early responses to emotional information according to genetic variation and clinical condition.

Neural correlates of facial emotion processing in infancy

“…This early detection of a fearful face in the brain should in theory precede and may drive the attentional bias to this kind of stimulus that has been observed in infant behaviors (Kotsoni et al., ). In the current study, a greater N290 response to fearful faces than both angry and happy faces was only shown in the right Occipitotemporal scalp regions (Figure , Supporting Information Figure ), which further implicates the N290 as a developmental precursor to the adult N170 component, whose amplitude is magnified in response to fearful faces mostly in the right Occipitotemporal electrodes (e.g., Faja et al., ; Leppänen et al., ). One unexpected finding is that while the amplitude of the N290 is larger in response to both fearful and happy faces than angry faces in the other four channel clusters, fearful, and happy face responses do not differ significantly in amplitude here, contrary to previous research with adults (Batty & Taylor, ; Rigato et al., ).…”

“…The N290 and P400 are thought to reflect the developmental precursors to the adult face‐sensitive N170, whose amplitude has also been found to be modulated by facial emotional expressions. In particular, the N170 has consistently been shown to be larger in response to fearful faces than happy or neutral faces in neurotypical adults (Batty & Taylor, ; Faja, Dawson, Aylward, Wijsman, & Webb, ; Leppänen et al., ; Rigato, Farroni, & Johnson, ).…”

Overlaps and distinctions between attention deficit/hyperactivity disorder and autism spectrum disorder in young adulthood: Systematic review and guiding framework for EEG-imaging research

“…For example, a study using house and face stimuli failed to replicate group differences in N170 between ASD and non-ASD controls at age 22 (Webb et al, 2012). Another study using open and closed mouth emotional faces also failed to find ASD-linked atypical profiles in N170 at age 23 (Faja et al, 2016). Instead, this latter study found ASD atypical profiles in the early posterior negativity (EPN), an enhanced negative-tending amplitude measured at 200–350 ms, thought to reflect perceptual attention underlying coding and recognition of facial expressions in the occipital and temporal cortex (Citron, 2012) (Table 1A).…”

“…Face processing tasks could, for example, consider a range of positive and negative emotions, so to establish if processing of specific emotions are disorder-specific (e.g., Raz and Dan, 2015a, 2015b). Additional parameters to consider are passive viewing versus active recognition and faces versus non-faces, given the inconsistency, even in the ASD literature, in relation to atypical face processing (e.g., Faja et al, 2016; O’Connor et al, 2005; Stavropoulos et al, 2016; Webb et al, 2012). Similarly, paradigms that aim to assess imitation/empathy may include conditions that allow for more precise functional interpretation, for example by considering both non-emotional (e.g., action observations; Bernier et al, 2007) and emotional conditions (e.g., pain observation; Fan et al, 2014), as well as measurements of different facets of empathy, such as emotional identification versus affect sharing (Coll et al, 2017).…”

Association Between 5-HTTLPR Polymorphism and the Risk of Autism: A Meta-Analysis Based on Case-Control Studies

“…The diagnosis of autism was confirmed by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and the Childhood Autism Rating Scale (CARS) in most studies. In addition, Faja et al (32) did not distinguish the ss and ls genotypes in their study, so we have to record the ss+ls genotype number.…”