No antidepressant-like acute effects of bright light on emotional information processing in healthy volunteers

Rationale Bright light treatment (BLT) is an efficacious antidepressant intervention, but its mechanism of action is not well understood. Antidepressant drugs acutely affect how emotional information is processed, pushing the brain to prioritise positive relative to negative input. Whether BLT could have a similar effect is not known to date. Objective To test whether BLT acutely influences emotional information processing similar to antidepressant drugs, using an established healthy volunteer assay. Methods Following a double-blind, parallel-group design, 49 healthy volunteers (18–65 years, 26 females) were randomly allocated to 60-min BLT (≥ 10,000 lux) or sham-placebo treatment early in the morning in autumn/winter. Immediately after treatment, emotional information processing was assessed using the Oxford Emotional Test Battery, a validated set of behavioural tasks tapping into emotional information processing in different cognitive domains. Participants also completed questionnaires before and after treatment to assess changes in subjective state. Results The BLT group did not show significantly more positively biased emotional information processing compared to the placebo group (p > 0.05 for all measures). After adjustment for pre-treatment scores, there were also no significant post-treatment differences between groups in subjective state (p > 0.05 for all measures). Conclusions BLT did not show immediate effects on emotional information processing in an established healthy volunteer assay. Thus, BLT might exert its clinical effects through a different (cognitive) mechanism than other antidepressant interventions. Future studies should corroborate this finding including clinical populations and more intensive treatment regimes, and control for potential chronobiological effects.

Specificity and wealth of autobiographical memories in restrictive and mixed anorexic patients

The reduced specificity of positive and negative autobiographical memories observed in anorexic (AN) patients may reflect a global disturbance in their emotional information processing. However, their emotional difficulties may differ according to the subtype of AN, implying possible differences in the manifestation of autobiographical memory impairments. The aims of the study were (1) to confirm the autobiographical memory deficits in AN patients in terms of specificity and wealth of memories, and (2) to compare autobiographical deficits according to the AN subtype: restrictive type (AR) or binge/purging type (AB). Ninety-five non-clinical (NC) individuals and 95 AN patients including 69 AR and 22 AB patients were administered the Williams’ and Scott’s Autobiographical Memory Test. The results confirmed a lack of specificity regardless of emotional valence in the overall AN patient group without any distinction of subtype, which was linked to the number of hospitalizations. When the AN subtype was considered, AR patients demonstrated reduced specificity for negative memories only, suggesting differences in emotional functioning or in the mechanisms underlying reduced specificity between AR and AB patients. Furthermore, the overall AN group demonstrated lower variability and complexity in their memory content than the NC group. However, this difference in the complexity of recalled memories was only found in response to negative cues. When AN subtypes were considered, AR patients showed fewer complex memories than NC individuals. Beyond a reduced specificity, AN patients also depict a poverty in the range of event recall and a difficulty in developing narrative content. The clinical implications of such autobiographical memory deficits need to be further investigated.

An Experimental Medicine Investigation of the Effects of Subacute Pramipexole Treatment on Emotional Information Processing in Healthy Volunteers

Treatment with the dopamine D2/D3 receptor agonist pramipexole has demonstrated promising clinical effects in patients with depression. However, the mechanisms through which pramipexole might alleviate depressive symptoms are currently not well understood. Conventional antidepressant drugs are thought to work by biasing the processing of emotional information in favour of positive relative to negative appraisal. In this study, we used an established experimental medicine assay to explore whether pramipexole treatment might have a similar effect. Employing a double-blind, parallel-group design, 40 healthy volunteers (aged 18 to 43 years, 50% female) were randomly allocated to 12 to 15 days of treatment with either pramipexole (at a peak daily dose of 1.0 mg pramipexole salt) or placebo. After treatment was established, emotional information processing was assessed on the neural level by measuring amygdala activity in response to positive and negative facial emotional expressions, using functional magnetic resonance imaging (MRI). In addition, behavioural measures of emotional information processing were collected at baseline and on drug, using an established computerized task battery, tapping into different cognitive domains. As predicted, pramipexole-treated participants, compared to those receiving placebo, showed decreased neural activity in response to negative (fearful) vs. positive (happy) facial expressions in bilateral amygdala. Contrary to our predictions, however, pramipexole treatment had no significant antidepressant-like effect on behavioural measures of emotional processing. This study provides the first experimental evidence that subacute pramipexole treatment in healthy volunteers modifies neural responses to emotional information in a manner that resembles the effects of conventional antidepressant drugs.

Oxytocin enhances basolateral amygdala activation and functional connectivity in autistic women while processing emotional faces

Background: Oxytocin is hypothesized to promote positive social interactions by enhancing the salience of social stimuli, which may be reflected by altered amygdala activation. While previous neuroimaging studies have reported that oxytocin enhances amygdala activation to emotional face stimuli in autistic men, effects in autistic women remain unclear. Methods: The influence of intranasal oxytocin on neural response to emotional faces vs. shapes were tested in 16 autistic and 21 non-autistic women by fMRI in a placebo-controlled, within-subjects, cross-over design. Effects of group (autistic vs. non-autistic) and drug condition (oxytocin vs. placebo) on the activation and functional connectivity of the basolateral amygdala, the brain’s “salience detector”, were assessed. Relationships between individual differences in autistic-like traits, social anxiety, salivary oxytocin levels, and amygdala activation were also explored.Results: Autistic and non-autistic women showed minimal activation differences in the placebo condition. Significant drug × group interactions were observed for both amygdala activation and functional connectivity. Oxytocin increased left basolateral amygdala activation among autistic women (35 voxel cluster, MNI coordinates of peak voxel = -22 -10 -28; mean change=+0.079%, t=3.159, ptukey=0.0166), but not non-autistic women (mean change =+0.003%, t=0.153, ptukey=0.999). Furthermore, oxytocin increased functional connectivity of the right basolateral amygdala with brain regions associated with socio-emotional information processing in autistic women, but not non-autistic women, thereby attenuating group connectivity differences observed in the placebo condition. Conclusions: This work demonstrates that intranasal oxytocin increases basolateral amygdala activation and connectivity in autistic women while processing emotional faces, which extends and specifies previous findings in autistic men.

Degree and Complexity of Non-conscious Emotional Information Processing – A Review of Masked Priming Studies

Whether and to what degree information can be processed non-consciously has been a matter of debate since the emergence of psychology as a science. Emotional information, in particular, has often been assumed to have a privileged status because of its relevance for well-being and survival (e.g., to detect a threat). Indeed, many studies have explored non-conscious processing of evaluative (i.e., “emotional” in a broad sense) or emotional (e.g., facial expressions) features using the “silver bullet” of non-consciousness research – the masked sequential priming paradigm. In its prototypical form, this paradigm involves the categorization of target stimuli according to valence (e.g., is the target positive or negative?). Each target is preceded by a briefly presented prime that is followed by a mask to constrain awareness. Non-conscious processing is inferred from subtle influences of the prime on target processing, that is, whether responses are faster if prime and target are valence-congruent or not. We will review this research with a focus on three questions: first, which methods are used in this area to establish non-conscious processing? Second, is there evidence for non-conscious extraction of evaluative information? Third, is there evidence for non-conscious processing beyond a simple valence (positive/negative) discrimination, for example, processing of emotion-specific information? We will highlight important current debates and potential directions in which the field will move in the future.

Working Memory Capacity For Faces With Different Levels of Emotional Valence

The capacity of visual working memory (VWM) depends on the complexity of the stimuli being processed. Emotional characteristics increase stimulus complexity and can interfere with the competition for cognitive resources. Studies involving emotional information processing are scarce and still produce contradicting results. In the present study, we investigated the capacity of VWM for faces with positive, negative, and neutral expressions. A modified change-detection task was used in two experiments, in which the number of faces and the emotional valence were manipulated. The results showed that VWM has a storage capacity of approximately two faces, which is fewer than the storage capacity identified for simpler stimuli. Our results reinforce the evidence that working memory can dynamically distribute its storage resources depending on both the amount and the emotional nature of the stimuli.

Forms and Functions of Affective Synchrony

[CHAPTER] The reproduction of another individual’s emotions in the self – the embodiment of perceived emotions – has been demonstrated to constitute one mechanism for emotional information processing. That is, seeing someone’s emotion expressions and using one’s own face to make the same expression helps the perceiver represent the emotion of the other. When members of a dyad mimic each other’s emotion expressions and by consequence converge in their underlying physiology over time we say that the dyad has reached a state of affective synchrony. The present chapter brings together recent theorizing and research on physiological and expressive affective synchrony. We propose affective synchrony serves three interrelated functions: it enables efficient information exchange, allows for interpersonal emotion regulation, and builds social bonds. We review evidence for the contexts in which affective synchrony arises, propose and evaluate the benefits and costs of achieving these states, and end by suggesting paths for future research in this area.