Modulatory effects of positive mood and approach motivation on reward processing: Two sides of the same coin?

Task demand modulates the effects of reward learning on emotional stimuli

The current study used event-related potentials (ERPs) to examine the ability of task demand in modulating the effect of reward association on the processing of emotional faces. In the learning phase, a high or low reward probability was paired with male or female facial photos of angry, happy, or neutral expressions. Then, in the test phase, task demand was manipulated by asking participants to discriminate the emotionality or the gender of the pre-learned face with no reward at stake. The ERP results in the test phase revealed that the fronto-central N1 (60-100 ms) and the VPP (160-210 ms) components were sensitive to the interaction between reward and emotion, in that the differences between the mean amplitudes for high- and low-reward conditions were significantly larger in the neutral face and angry face conditions than in the happy face condition. Moreover, reward association and task demand showed a significant interaction over the right hemisphere for the N170 component (140-180 ms), with amplitude difference between high- and low-reward conditions being larger in the emotion task than that in the gender task. The later N2pc component exhibited an interaction between task demand and emotionality, in that happy faces elicited larger N2pc difference waves than angry and neutral faces did in the emotion task, but neutral faces elicited larger N2pc difference waves than angry faces did in the gender task. The N2pc effect aligned with behavioral performance. These results suggest that reward association acts as an 'emotional tagging' to imbue neutral or angry faces with motivational significance at early time windows. Task demand functions in a top-down way to modulate the deployment of attentional resources at the later attentional selection stage, but does not affect the early automatic processing of either emotion or reward association.

Test-retest reliability of reinforcement learning parameters

It has recently been suggested that parameter estimates of computational models can be used to understand individual differences at the process level. One area of research in which this approach, called computational phenotyping, has taken hold is computational psychiatry. One requirement for successful computational phenotyping is that behavior and parameters are stable over time. Surprisingly, the test-retest reliability of behavior and model parameters remains unknown for most experimental tasks and models. The present study seeks to close this gap by investigating the test-retest reliability of canonical reinforcement learning models in the context of two often-used learning paradigms: a two-armed bandit and a reversal learning task. We tested independent cohorts for the two tasks (N = 69 and N = 47) via an online testing platform with a between-test interval of five weeks. Whereas reliability was high for personality and cognitive measures (with ICCs ranging from .67 to .93), it was generally poor for the parameter estimates of the reinforcement learning models (with ICCs ranging from .02 to .52 for the bandit task and from .01 to .71 for the reversal learning task). Given that simulations indicated that our procedures could detect high test-retest reliability, this suggests that a significant proportion of the variability must be ascribed to the participants themselves. In support of that hypothesis, we show that mood (stress and happiness) can partly explain within-participant variability. Taken together, these results are critical for current practices in computational phenotyping and suggest that individual variability should be taken into account in the future development of the field.

Machine learning reveals differential effects of depression and anxiety on reward and punishment processing

Recent studies suggest that depression and anxiety are associated with unique aspects of EEG responses to reward and punishment, respectively; also, abnormal responses to punishment in depressed individuals are related to anxiety, the symptoms of which are comorbid with depression. In a non-clinical sample, we aimed to investigate the relationships between reward processing and anxiety, between punishment processing and anxiety, between reward processing and depression, and between punishment processing and depression. Towards this aim, we separated feedback-related brain activity into delta and theta bands to isolate activity that indexes functionally distinct processes. Based on the delta/theta frequency and feedback valence, we then used machine learning (ML) to classify individuals with high severity of depressive symptoms and individuals with high severity of anxiety symptoms versus controls. The significant difference between the depression and control groups was driven mainly by delta activity; there were no differences between reward- and punishment-theta activities. The high severity of anxiety symptoms was marginally more strongly associated with the punishment- than the reward-theta feedback processing. The findings provide new insights into the differences in the impacts of anxiety and depression on reward and punishment processing; our study shows the utility of ML in testing brain-behavior hypotheses and emphasizes the joint effect of theta-RewP/FRN and delta frequency on feedback-related brain activity.

Neural correlates of evaluations of non-binary social feedback: An EEG study

PURPOSE

In complex and diverse social circumstances, decision making is affected by social feedback. Although previous studies have examined the electrophysiological correlates of social feedback with a binary valence, those related to non-binary feedback, or the magnitude of social feedback, remain unclear. This study investigated the electrophysiological correlates of non-binary social feedback and subsequent action selection processing.

METHODS

Participants were asked to complete a Gabor patch direction judgment task in which they were required to make judgments before and after receiving social feedback. They were informed that the feedback stimuli represented the degree to which other participants made the same choice.

RESULTS & CONCLUSION

The results revealed that feedback that was highly concordant with the participant's judgments elicited greater P300 activity, which was associated with the fulfillment of expectations regarding social reward. Moreover, moderately concordant feedback induced stronger theta band power, which may indicate monitoring of subjective conflict. Temporal changes in theta power during feedback phase may also relate to adjustments in prediction error. Additionally, when an initial judgment was maintained following social feedback, we observed a stronger increase in beta power, indicating an association with post-social-feedback action processing.

Effects of Tai Chi and Qigong on cognitive and physical functions in older adults: systematic review, meta-analysis, and meta-regression of randomized clinical trials

BACKGROUND

Older adults experience age-related declines in physical and cognitive functions due to interactions between aging and chronic diseases. Tai Chi and Qigong (TCQ) might be beneficial in improving the physical function and delaying the cognitive decline of this population. The potential underlying mechanism was explored to determine the effects of TCQ on cognitive function via direct or indirect pathways.

PURPOSE

The objective of this systematic review was to determine the effects of TCQ on cognitive and physical functions in older adults using meta-analysis, and to determine the impact of TCQ on cognitive function while controlling for physical function using a meta-regression approach.

METHODS

A systematic search of 13 electronic databases (in English, Korean, and Chinese languages) identified 10,292 potentially eligible studies published between inception and May 2022. The bias in individual studies was assessed using the Cochrane Risk of Bias (version 2.0) tool. The heterogeneity of the studies was evaluated using a 95% prediction interval, and the meta-analysis and meta-regression were implemented using the Comprehensive Meta-Analysis (version 3) software.

RESULTS

Our search identified 17 randomized studies (n = 2,365, mean age = 70.3 years). The results of the meta-analysis that used a random-effects model indicated that TCQ had significant effects on both cognitive (Hedges' g = 0.29, 95% confidence interval [CI] = 0.17 to 0.42) and physical (Hedges' g = 0.32, 95% CI = 0.19 to 0.44) functions. We used meta-regression to explore the effect size of TCQ in association with physical function level. The regression model was significant (Q = 25.01, p = .070), and 55% of the heterogeneity was explained by physical function as a moderator variable. The effects of TCQ on cognitive function remained significant in this model when controlling for the effect of physical function (β = 0.46, p = .011).

CONCLUSION

This meta-regression of 17 randomized studies strongly suggests that TCQ has beneficial effects on physical and cognitive functions in older adults. The effect of TCQ on cognitive function remained significant after taking into account the significant effects of physical function as a moderator. The findings imply the potential health benefits of TCQ by promoting cognitive function in older adults directly and indirectly through enhancing physical function. PROSPERO REGISTRATION NUMBER: *PROSPERO international prospective register of systematic reviews, registration ID CRD42023394358.

The basal ganglia and the cerebellum in human emotion

The basal ganglia (BG) and the cerebellum historically have been relegated to a functional role in producing or modulating motor output. Recent research, however, has emphasized the importance of these subcortical structures in multiple functional domains, including affective processes such as emotion recognition, subjective feeling elicitation and reward valuation. The pathways through the thalamus that connect the BG and cerebellum directly to each other and with extensive regions of the cortex provide a structural basis for their combined influence on limbic function. By regulating cortical oscillations to guide learning and strengthening rewarded behaviors or thought patterns to achieve a desired goal state, these regions can shape the way an individual processes emotional stimuli. This review will discuss the basic structure and function of the BG and cerebellum and propose an updated view of their functional role in human affective processing.