Pupil response to affective stimuli: A biomarker of early conduct problems in young children

Childhood conduct problems have been associated with reduced autonomic arousal to negative cues indicative of an insensitivity to aversive stimuli, with mixed evidence in response to positive cues. Autonomic arousal to affective stimuli has traditionally been measured through galvanic skin responses and heart-rate, despite evidence that pupillometry is more reliable and practically beneficial (i.e., no wires are attached to the participant). The current study is the first to examine abnormal pupillary responsivity to affective stimuli as a biomarker for childhood conduct problems. We measured pupil reactivity to negative, positive and neutral images in 131 children aged 4–7 years, who were referred by their teachers for being at risk of future psychopathology. We assessed relationships between pupil response to the images and teacher-rated scores on the Strengths and Difficulties Questionnaire (SDQ), which indexed child conduct problems and their overlapping emotional, behavioural and social difficulties. Reduced pupil dilation to negative images was associated with significantly increased conduct, hyperactivity, emotional and peer problems, as well as reduced prosocial behaviour. Composite scores for disruptive behaviour and emotional difficulties both uniquely predicted blunted pupil response to negative threat stimuli; there were no relations with pupil responses to positive images. These findings highlight that blunted pupil responsivity to negative stimuli serves as a biomarker for early disruptive behavioural problems and affective difficulties. Pupillometry offers an inexpensive, fast and non-intrusive measure to help identify children who are showing early disruptive behaviour or experiencing affective difficulties, which can provide opportunities for preventative intervention to avoid further psychopathology

The association between hyperactive behaviour and cognitive inhibition impairments in young children

Hyperactivity is one of the core features of attention-deficit hyperactivity disorder (ADHD), and yet there is evidence that hyperactive behavior in children with ADHD is not ubiquitous and could be a compensatory response to high cognitive demands. No research has yet objectively measured hyperactive behavior in young children who are demonstrating early signs of ADHD or examined the role of emotional state on hyperactivity levels.The current study measured motor activity using actigraphy during baseline, cognitive inhibition (Flanker task), and emotion arousing (Impossibly Perfect Circles task) conditions in 95 children aged 4–7 years old with developmental difficulties, including emerging symptoms of ADHD. We examined the relationship between objectively recorded activity, parent-rated hyperactivity problems, using the Strengths and Difficulties Questionnaire (SDQ), and cognitive inhibition task performance.Parent ratings of hyperactivity (but not inattention) symptoms were positively related to recorded hyperactivity, and this relationship was specific to activity measured during the cognitive inhibition task. Impaired cognitive inhibition performance was related to increased measured movement and this association was strongest in children who were rated as having the highest levels of hyperactive behavior.These findings confirm theoretically predicted associations between objectively recorded hyperactivity and impaired executive functioning and support the notion that hyperactivity in children emerges in response to high cognitive demands. The results encourage further investigation into the role of hyperactivity as a transdiagnostic dimension that can explain variation within and between different types of diagnostic classifications

Long-range vibrational dynamics are directed by Watson-Crick base-pairing in duplex DNA

Ultrafast two-dimensional infrared (2D-IR) spectroscopy of a 15-mer A-T DNA duplex in solution has revealed structure-dependent vibrational coupling and energy transfer processes linking bases with the sugar-phosphate backbone. Duplex melting induces significant changes in the positions of off-diagonal peaks linking carbonyl and ring-stretching vibrational modes of the adenine and thymine bases with vibrations of the phosphate group and phosphodiester linkage. These indicate that Watson-Crick hydrogen bonding and helix formation leads to a unique vibrational coupling arrangement of base vibrational modes with those of the phosphate unit. Based on observations from time-resolved 2D-IR data, we conclude that rapid energy transfer processes occur between base and backbone, mediated by additional modes located on the deoxyribose moiety within the same nucleotide. These relaxation dynamics are insensitive to duplex melting, showing that efficient intramo-lecular energy relaxation to the solvent via the phosphate groups is the key to excess energy dissipation in both single and double-stranded DNA

Emotional modulation of the pupil in psychopathy: a test of the response modulation hypothesis

Some aspects of psychopathy may be underpinned by a deficit in processing emotional information, although there is evidence that this impairment only emerges when the affective cues are not central to ongoing goal-directed behaviour. However, this hypothesis has not been explored previously in relation to autonomic reactivity to emotional stimuli. The current study investigated this in a large (N =174) community sample by examining changes in pupil diameter, a measure of autonomic nervous system activity, while participants viewed images that were either neutral in content or contained highly arousing/emotional content. Participants’ attentional focus was manipulated across two tasks, such that participants either focused on whether the image contained emotional content (emotion-focus) or whether there were people present in the image (alternate-focus). Psychopathy was conceptualised via the Triarchic model of boldness, meanness and disinhibition. As expected, the arousing images caused greater pupil dilation compared to neutral images. However, the magnitude of this dilation was not moderated by any aspect of psychopathy regardless of the participant’s attentional focus. It may be that reduced pupil reactivity to emotional stimuli is only expressed at high levels of psychopathy not normally found in community samples, or that participants with high traits of psychopathy in the community were still able to sufficiently attend to the emotional components of the images to overcome any autonomic deficits regardless of their attentional focus. Further research is needed to explore these possibilities

Facial emotion recognition in adopted children

Children adopted from public care are more likely to experience emotional and behavioural problems. We investigated two aspects of emotion recognition that may be associated with these outcomes, including discrimination accuracy of emotions and response bias, in a mixed-method, multi-informant study of 4-to-8-year old children adopted from local authority care in the UK (N = 42). We compared adopted children’s emotion recognition performance to that of a comparison group of children living with their birth families, who were matched by age, sex, and teacher-rated total difficulties on the Strengths and Difficulties Questionnaire (SDQ, N = 42). We also examined relationships between adopted children’s emotion recognition skills and their pre-adoptive histories of early adversity (indexed by cumulative adverse childhood experiences), their parent- and teacher-rated emotional and behavioural problems, and their parents’ coded warmth during a Five Minute Speech Sample. Adopted children showed significantly worse facial emotion discrimination accuracy of sad and angry faces than non-adopted children. Adopted children’s discrimination accuracy of scared and neutral faces was negatively associated with parent-reported behavioural problems, and discrimination accuracy of angry and scared faces was associated with parent- and teacher-reported emotional problems. Contrary to expectations, children who experienced more recorded pre-adoptive early adversity were more accurate in identifying negative emotions. Warm adoptive parenting was associated with fewer behavioural problems, and a lower tendency for children to incorrectly identify faces as angry. Study limitations and implications for intervention strategies to support adopted children’s emotion recognition and psychological adjustment are discussed

Intramolecular Cohesion of Coils Mediated by Phenylalanine–Glycine Motifs in the Natively Unfolded Domain of a Nucleoporin

The nuclear pore complex (NPC) provides the sole aqueous conduit for macromolecular exchange between the nucleus and the cytoplasm of cells. Its diffusion conduit contains a size-selective gate formed by a family of NPC proteins that feature large, natively unfolded domains with phenylalanine–glycine repeats (FG domains). These domains of nucleoporins play key roles in establishing the NPC permeability barrier, but little is known about their dynamic structure. Here we used molecular modeling and biophysical techniques to characterize the dynamic ensemble of structures of a representative FG domain from the yeast nucleoporin Nup116. The results showed that its FG motifs function as intramolecular cohesion elements that impart order to the FG domain and compact its ensemble of structures into native premolten globular configurations. At the NPC, the FG motifs of nucleoporins may exert this cohesive effect intermolecularly as well as intramolecularly to form a malleable yet cohesive quaternary structure composed of highly flexible polypeptide chains. Dynamic shifts in the equilibrium or competition between intra- and intermolecular FG motif interactions could facilitate the rapid and reversible structural transitions at the NPC conduit needed to accommodate passing karyopherin–cargo complexes of various shapes and sizes while simultaneously maintaining a size-selective gate against protein diffusion

As Far as the Eye Can See: Relationship between Psychopathic Traits and Pupil Response to Affective Stimuli

Psychopathic individuals show a range of affective processing deficits, typically associated with the interpersonal/affective component of psychopathy. However, previous research has been inconsistent as to whether psychopathy, within both offender and community populations, is associated with deficient autonomic responses to the simple presentation of affective stimuli. Changes in pupil diameter occur in response to emotionally arousing stimuli and can be used as an objective indicator of physiological reactivity to emotion. This study used pupillometry to explore whether psychopathic traits within a community sample were associated with hypo-responsivity to the affective content of stimuli. Pupil activity was recorded for 102 adult (52 female) community participants in response to affective (both negative and positive affect) and affectively neutral stimuli, that included images of scenes, static facial expressions, dynamic facial expressions and sound-clips. Psychopathic traits were measured using the Triarchic Psychopathy Measure. Pupil diameter was larger in response to negative stimuli, but comparable pupil size was demonstrated across pleasant and neutral stimuli. A linear relationship between subjective arousal and pupil diameter was found in response to sound-clips, but was not evident in response to scenes. Contrary to predictions, psychopathy was unrelated to emotional modulation of pupil diameter across all stimuli. The findings were the same when participant gender was considered. This suggests that psychopathy within a community sample is not associated with autonomic hypo-responsivity to affective stimuli, and this effect is discussed in relation to later defensive/appetitive mobilisation deficits