Frontal Alpha Asymmetry: a potential biomarker of approach-withdrawal motivation towards pain.

Pain-related catastrophising is a maladaptive coping strategy known to have a strong influence on clinical pain outcomes and treatment efficacy. Mounting evidence suggests catastrophising is associated with resting-state EEG frontal alpha asymmetry (FAA) patterns reflective of greater relative right frontal activity, thought to underly withdrawal motivation and negative affect. Notwithstanding, knowledge on the neurophysiological basis of catastrophising remains limited. The present study aims to investigate whether such relationship occurs in the situational context of experimental pain, and how FAA is modulated by pain and placebo treatment. 35 participants completed the Pain Catastrophising Scale (PCS) questionnaire prior to EEG recordings during cold pressor test (CPT)-induced tonic pain with or without prior application of placebo cream. There was a negative correlation between FAA and PCS-subscale helplessness scores, but not rumination or magnification, during the pre-placebo CPT condition. Moreover, FAA scores were shown to increase significantly in response to pain, indicative of greater relative left frontal activity that relates to approach-oriented behaviours. Placebo treatment elicited a decrease in FAA in low helplessness scorers, but no significant effects in individuals scoring above the mean on PCS-helplessness. These findings suggest that, during painful events, FAA may reflect the motivational drive to obtain reward of pain relief, which may be diminished in individuals who are prone to feel helpless about their pain. This study provides valuable insights into biomarkers of pain-related catastrophising and prospects of identifying promising targets of brain-based therapies for chronic pain management.

Resting Frontal Eeg Asymmetry and Personality Traits: A Meta–Analysis

Frontal asymmetry has been widely used as a marker of emotion, motivation, and psychopathology. When assessed during the resting state, it is regarded as an index of trait approach and withdrawal motivation. However, the replicability of these associations with personality is currently unclear. The present meta–analysis seeks to provide a comprehensive quantitative review of the relationship between personality traits and resting electroencephalographic (EEG) frontal asymmetry. We distinguished five personality clusters: extraversion, neuroticism, impulsivity, anger, and defensiveness. Data from 79 independent samples with overall 5700 participants were included in the meta–analysis. The results revealed that less than 0.4% of the variance in extraversion and neuroticism could be explained by resting frontal asymmetry. Similarly, a small effect was observed for trait anger, and a small–sized to medium–sized effect was observed for defensiveness, although the number of studies was very low. No significant effect emerged for impulsivity. The effects were further reduced after adjustment for publication bias. Given some evidence for heterogeneity, sub–traits were analysed, and methodological moderators were investigated. Based on the results, we conclude that the validity of resting frontal asymmetry as a marker for personality is not supported. Finally, recommendations are given to increase the replicability of frontal asymmetry research. © 2019 European Association of Personality Psychology

Psychological Response to Sound Stimuli Evaluated by EEG

Psychological responses to two kinds of sound stimuli (scary and soothing), as assessed by the Anterior Asymmetry and Emotion (AAE) and Comfort Vector (CV) models which are based on the prefrontal alpha wave, were investigated and the relation between their results is discussed. For the scary sound stimulus, subjects who showed greater withdrawal motivation (AAE) displayed a decreased pleasant state (CV), while subjects who showed higher approach motivation displayed opposite affective direction. There was a correlation between the AAE and CV models for the scary stimulus, but no correlation for the soothing stimulus. Both motivational and affective states could be evaluated by a combination of AAE and CV models. We suggest that joint consideration of these two models could lead to the multifaceted evaluation of a psychological state.

Cognitive, Affective, and Motivational Changes during Ostracism: An ERP, EMG, and EEG Study Using a Computerized Cyberball Task

Individuals are known to be highly sensitive to signs of ostracism, such as being ignored or excluded; however, the cognitive, affective, and motivational processes underlying ostracism have remained unclear. We investigated temporal changes in these psychological states resulting from being ostracized by a computer. Using event-related brain potentials (ERPs), the facial electromyogram (EMG), and electroencephalogram (EEG), we focused on the P3b amplitude, corrugator supercilii activity, and frontal EEG asymmetry, which reflect attention directed at stimuli, negative affect, and approach/withdrawal motivation, respectively. Results of the P3b and corrugator supercilii activity replicated findings of previous studies on being ostracized by humans. The mean amplitude of the P3b wave decreased, and facial EMG activity increased over time. In addition, frontal EEG asymmetry changed from relative left frontal activation, suggestive of approach motivation, to relative right frontal activation, indicative of withdrawal motivation. These findings suggest that ostracism by a computer-generated opponent is an aversive experience that in time changes the psychological status of ostracized people, similar to ostracism by human. Our findings also imply that frontal EEG asymmetry is a useful index for investigating ostracism. Results of this study suggest that ostracism has well developed neurobiological foundations.