Ruolei Gu

Anxiety and feedback negativity

It has been suggested that anxious individuals are more prone to feel that negative outcomes are particularly extreme and to interpret ambiguous outcomes as negative compared to nonanxious individuals. Previous studies have demonstrated that the feedback negativity (FN) component of event-related brain potential (ERP) is sensitive to outcome evaluation and outcome expectancy. Hence, we predicted that the FN should be different between high trait-anxiety (HTA) and low trait-anxiety (LTA) individuals. To test our hypothesis, the ERPs were recorded during a simple monetary gambling task. The FN was measured as a difference wave created across conditions. We found that the amplitude of the FN indicating negative versus positive outcomes was significantly larger for LTA individuals compared to HTA individuals. However, there was no significant difference in the FN between groups in response to ambiguous versus positive outcomes. The results indicate that there is a relationship between the FN and individual differences in anxiety. We suggest that these results reflect the impact of anxiety on outcome expectation. Our results challenge the reinforcement learning theory of error-related negativity, which proposes that ERN and FN reflect the same cognitive process.

Neural Basis of Emotional Decision Making in Trait Anxiety

Although trait anxiety has been associated with risk decision making, whether it is related to risk per se or to the feeling of the risk, as well as the underlying neurocognitive mechanisms, remains unclear. Using a decision-making task with a manipulation of frame (i.e., written description of options as a potential gain or loss) and functional magnetic resonance imaging, we investigated the neurocognitive relationship between trait anxiety and decision making. The classic framing effect was observed: participants chose the safe option when it was described as a potential gain, but they avoided the same option when it was described as a potential loss. Most importantly, trait anxiety was positively correlated with this behavioral bias. Trait anxiety was also positively correlated with amygdala-based “emotional” system activation and its coupling with the ventromedial prefrontal cortex (vmPFC) when decisions were consistent with the framing effect, but negatively correlated with the dorsal anterior cingulate cortex (dACC)-based “analytic” system activation and its connectivity to the vmPFC when decisions ran counter to the framing effect. Our findings suggest that trait anxiety is not associated with subjective risk preference but an evaluative bias of emotional information in decision making, underpinned by a hyperactive emotional system and a hypoactive analytic system in the brain.

Three stages of emotional word processing: an ERP study with rapid serial visual presentation

Rapid responses to emotional words play a crucial role in social communication. This study employed event-related potentials to examine the time course of neural dynamics involved in emotional word processing. Participants performed a dual-target task in which positive, negative and neutral adjectives were rapidly presented. The early occipital P1 was found larger when elicited by negative words, indicating that the first stage of emotional word processing mainly differentiates between non-threatening and potentially threatening information. The N170 and the early posterior negativity were larger for positive and negative words, reflecting the emotional/non-emotional discrimination stage of word processing. The late positive component not only distinguished emotional words from neutral words, but also differentiated between positive and negative words. This represents the third stage of emotional word processing, the emotion separation. Present results indicated that, similar with the three-stage model of facial expression processing; the neural processing of emotional words can also be divided into three stages. These findings prompt us to believe that the nature of emotion can be analyzed by the brain independent of stimulus type, and that the three-stage scheme may be a common model for emotional information processing in the context of limited attentional resources.

An electrophysiological index of changes in risk decision-making strategies

Human decision-making is significantly modulated by previously experienced outcomes. Using event-related potentials (ERPs), we examined whether ERP components evoked by outcome feedbacks could serve as biomarkers to signal the influence of current outcome evaluation on subsequent decision-making. In this study, 18 adult volunteers participated in a simple monetary gambling task, in which they were asked to choose between two options that differed in risk. Their decisions were immediately followed by outcome presentation. Temporospatial principle component analysis (PCA) was applied to the outcome-onset locked ERPs in the 200-1000 ms time window. The PCA factors that approximated classical ERP components (P2, feedback-related negativity, P3a, and P3b) in terms of time course and scalp distribution were tested for their association with subsequent decision-making strategies. Our results revealed that a fronto-central PCA factor approximating the classical P3a was related to changes of decision-making strategies on subsequent trials. The decision to switch between high- and low-risk options resulted in a larger P3a relative to the decision to retain the same choice. According to the results, we suggest that the amplitude of the fronto-central P3a is an electrophysiological index of the influence of current outcome on subsequent risk decision-making. Furthermore, the ERP source analysis indicated that the activations of the frontopolar cortex and sensorimotor cortex were involved in subsequent changes of strategies, which enriches our understanding of the neural mechanisms of adjusting decision-making strategies based on previous experience.

Diffusion of responsibility attenuates altruistic punishment: A functional magnetic resonance imaging effective connectivity study

Humans altruistically punish violators of social norms to enforce cooperation and pro‐social behaviors. However, such altruistic behaviors diminish when others are present, due to a diffusion of responsibility. We investigated the neural signatures underlying the modulations of diffusion of responsibility on altruistic punishment, conjoining a third‐party punishment task with event‐related functional magnetic resonance imaging and multivariate Granger causality mapping. In our study, participants acted as impartial third‐party decision‐makers and decided how to punish norm violations under two different social contexts: alone (i.e., full responsibility) or in the presence of putative other third‐party decision makers (i.e., diffused responsibility). Our behavioral results demonstrated that the diffusion of responsibility served as a mediator of context‐dependent punishment. In the presence of putative others, participants who felt less responsible also punished less severely in response to norm violations. Our neural results revealed that underlying this behavioral effect was a network of interconnected brain regions. For unfair relative to fair splits, the presence of others led to attenuated responses in brain regions implicated in signaling norm violations (e.g., AI) and to increased responses in brain regions implicated in calculating values of norm violations (e.g., vmPFC, precuneus) and mentalizing about others (dmPFC). The dmPFC acted as the driver of the punishment network, modulating target regions, such as AI, vmPFC, and precuneus, to adjust altruistic punishment behavior. Our results uncovered the neural basis of the influence of diffusion of responsibility on altruistic punishment and highlighted the role of the mentalizing network in this important phenomenon. Hum Brain Mapp 37:663–677, 2016.

Arousal modulates valence effects on both early and late stages of affective picture processing in a passive viewing task.

Valence and arousal are primary dimensions of affective stimuli. An interaction of these two factors on affective processing is largely unknown. In this study, the processing of affective pictures was investigated in an orthogonal valence (positive vs. negative) by arousal (high vs. low) task design. Participants were instructed to passively view each presented picture and did not need to make any responses. The valence by arousal interaction was observed on three event-related potential (ERP) components, including the P2 (160–190 ms), N2 (220–320 ms) and late positive potential (LPP) (400–700 ms). This interaction revealed that negative pictures evoked larger neural responses compared with positive pictures (i.e., negative bias) at the high-arousal level, whereas negative pictures evoked smaller neural responses than positive pictures (i.e., positive offset) at the low-arousal level. The current results suggest that the effect of emotional valence on affective picture perception is modulated by levels of arousal at both early and late stages of processing. Finally, the main effect of valence was evident in the P1 component (90–110 ms) and arousal effect in the N1 component (120–150 ms).

The temporal course of the influence of anxiety on fairness considerations

This study investigated the potential causes of anxious peoples social avoidance. The classic ultimatum game was utilized in concert with electroencephalogram recording. Participants were divided into two groups according to levels of trait anxiety as identified by a self-report scale. The behavioral results indicate that high-anxious participants were more prone to reject human-proposed than computer-proposed unequal offers compared to their low-anxious counterparts. The event-related potential results indicate that the high-anxious group showed a larger feedback-related negativity when receiving unequal monetary offers than equal ones, and a larger P3 when receiving human-proposed offers than computer-proposed ones, but these effects were absent in the low-anxious group. We suggest anxious peoples social avoidance results from hypersensitivity to unequal distributions during interpersonal interactions.

Woulda, coulda, shoulda: The evaluation and the impact of the alternative outcome

The alternative outcome refers to the outcome of the unselected option in decision-making tasks, which has significant influence on the chosen outcome evaluation. Most paradigms have presented the alternative outcome either after or simultaneous with the chosen outcome, which complicates the observation on the brain activity associated with the alternative outcome. To circumvent this perceived shortcoming, we modified the classic paradigm designed by Yeung and Sanfey (2004) such that the alternative outcome was presented before the chosen outcome in each trial while an electroencephalogram was recorded. The feedback-related negativity (FRN) elicited by the positive alternative outcome was larger than that elicited by the negative alternative outcome, suggesting that the participants evaluated the positive alternative outcome as negative feedback. Moreover, the FRN and the P3 elicited by the chosen outcome were influenced by the valence of the alternative outcome. The current study reveals that the alternative outcome is treated as important information even though it is economically neutral.

The impact of anxiety on social decision-making: Behavioral and electrodermal findings

Anxiety plays an important role in social behavior. For instance, high-anxious individuals are more likely to avoid such social interactions as communicating with strangers. In this study, we investigate the impact of anxiety on social decision-making. The classic ultimatum game (UG) paradigm was utilized in concert with skin conductance recording. Behavioral results reveal that when playing as responders, high-trait anxiety (HTA) participants with lower levels of self-esteem, as well as low-trait anxiety (LTA) participants with higher levels of impulsivity, were more likely to accept human-proposed inequitable offers. In addition, the HTA participants rejected more computer-proposed inequitable offers than did LTA participants. Moreover, the skin conductance response to inequitable offers was correlated with levels of anxiety in the HTA group, but not in the LTA group. In conclusion, people differing in levels of anxiety showed distinct behavior patterns and autonomic neural responses during social decision-making, whereas the levels of self-esteem, impulsivity, and depression might be additional moderating factors. These findings contextualize high-anxious peoples avoidance tendency in social interaction.

Linking brain electrical signals elicited by current outcomes with future risk decision-making

The experience of current outcomes influences future decisions in various ways. The neural mechanism of this phenomenon may help to clarify the determinants of decision-making. In this study, thirty-nine young adults finished a risky gambling task by choosing between a high- and a low-risk option in each trial during electroencephalographic data collection. We found that risk-taking strategies significantly modulated mean amplitudes of the event-related potential (ERP) component P3, particularly at the central scalp. The event-related spectral perturbation and the inter-trial coherence measurements of the independent component analysis (ICA) data indicated that the “stay” vs. “switch” electrophysiological difference associated with subsequent decision-making was mainly due to fronto-central theta and left/right mu independent components. Event-related cross-coherence results suggested that the neural information of action monitoring and updating emerged in the fronto-central cortex and propagated to sensorimotor area for further behavior adjustment. Based on these findings of ERP and event-related oscillation (ERO) measures, we propose a neural model of the influence of current outcomes on future decisions.