Stimulus Novelty Inhibits Reward Evaluation: EEG Evidence.

<p id=C2>Feedback processing plays an important role in behavior modification and knowledge acquisition. Previous research has explored the neurophysiological basis and psychological functions of feedback processing and proposed corresponding theoretical models, but little is known about how working memory (WM) load affects feedback processing. Studies have reported electrophysiological indicators, such as the reward positivity (RewP) and the related theta and delta oscillations, the P3 and the late positive potential (LPP), during brain processing feedback. This study will further examine how WM load modulates these electrophysiological components and their corresponding cognitive functions. <break/>In the present study, we used a dual-task paradigm to investigate feedback processing under different WM load conditions. This study included 25 healthy college students and used a 3 (WM load: baseline vs. low WM load vs. high WM load) by 2 (feedback valence: positive vs. negative) within-participant factorial design. During the experiment, participants were asked to perform a simple gambling task and a spatial memory task simultaneously, and the magnitude of the WM load included three conditions: baseline, low WM load and high WM load. The RewP generated in the early stage of feedback processing and the LPP generated in the late stage of feedback processing, as well as the delta and theta oscillations related to feedback evaluation, were analyzed. <break/>The behavioral results showed that the accuracy of the low WM load condition was significantly higher than that of the high WM load condition. The electrophysiological results showed that the amplitudes of the RewP were sensitive to feedback valence, with positive feedback evoking larger RewP than negative feedback, but the RewP was not affected by the WM load. There was no difference in the P3 amplitude under the different WM load conditions. For the LPP, there was a significant interaction between the WM load and feedback valence. Further analysis revealed that, in the high WM load condition, the LPP amplitude was larger for positive feedback than for negative feedback. The theta power differences between negative feedback and positive feedback were larger in the low WM load condition than in the high WM load condition. For delta oscillation, the power was increased after positive feedback compared to after negative feedback, but there was no difference at different WM load levels. <break/>The RewP results indicate that the participants process feedback valence information well under all three WM load conditions in the experiment. The LPP results suggest that the participants assigned additional emotional motivation to the feedback outcome as a result of their cognitive efforts under high WM load conditions. The ERP results for the time domain dimension showed that the effect of the WM load on feedback processing was most noticeable in the later stages of feedback processing. Moreover, these observations support the argument that the RewP and theta power reflect distinct cognitive phenomena; namely, the RewP reflects the processing of feedback valence in the anterior cingulate cortex (ACC), whereas theta oscillations reflect the role of the ACC in cognitive control. The WM load selectively modulates the cognitive control process in the ACC.

How do social interactions form and modulate the neural representations of specific complex signals? This question can be addressed in the songbird auditory system. Like humans, songbirds learn to vocalize by imitating tutors heard during development. These learned vocalizations are important in reproductive and social interactions and in individual recognition. As a model for the social reinforcement of particular songs, male zebra finches were trained to peck for a food reward in response to one song stimulus (GO) and to withhold responding for another (NoGO). After performance reached criterion, single and multiunit neural responses to both trained and novel stimuli were obtained from multiple electrodes inserted bilaterally into two songbird auditory processing areas [caudomedial mesopallium (CMM) and caudomedial nidopallium (NCM)] of awake, restrained birds. Neurons in these areas undergo stimulus-specific adaptation to repeated song stimuli, and responses to familiar stimuli adapt more slowly than to novel stimuli. The results show that auditory responses differed in NCM and CMM for trained (GO and NoGO) stimuli vs. novel song stimuli. When subjects were grouped by the number of training days required to reach criterion, fast learners showed larger neural responses and faster stimulus-specific adaptation to all stimuli than slow learners in both areas. Furthermore, responses in NCM of fast learners were more strongly left-lateralized than in slow learners. Thus auditory responses in these sensory areas not only encode stimulus familiarity, but also reflect behavioral reinforcement in our paradigm, and can potentially be modulated by social interactions.

Understanding the interplay between attachment style, emotional processing, and neural responses is crucial for comprehending the diverse ways individuals function socially and emotionally. While previous research has contributed to our knowledge of how attachment style influences emotional processing, there is still a gap in the literature when it comes to investigating emotional feedback using event-related potentials (ERPs) within a cognitive framework. This study aims to address this gap by examining the effects of attachment style and feedback valence on ERP components, specifically focusing on the P200 and P400. The findings reveal significant effects of attachment style and feedback valence on both components. In insecure attachment styles, noticeable shifts in relative energy are observed during the transition from negative to positive feedback for both the P200 and P400. Conversely, individuals with secure attachment styles exhibit minimal to moderate variations in relative energy, consistently maintaining a lower P200 energy level. Additionally, both secure and insecure individuals demonstrate heightened intensity in the P400 component in response to positive feedback. These findings underscore the influential role of attachment style in shaping emotional reactivity and regulation, emphasizing the significance of attachment theory in understanding individual differences in social and emotional functioning. This study provides novel insights into the neural mechanisms underlying the influence of attachment style on emotional processing within the context of cognitive task performance. Future research should consider diverse participant samples, employ objective measures of attachment, and utilize longitudinal designs to further explore the neural processes associated with attachment.

Preexposing subjects to visual stimuli is sufficient to establish a subsequent preference, even when previous exposure is subliminal, such that explicit recognition is at chance. This influence of previous exposure on preference judgments, known as the "mere exposure effect," is a form of unconscious memory. The present functional neuroimaging study examines the mechanism of this effect. Nine volunteer subjects were studied using functional imaging while making forced choice judgments about abstract stimuli on the basis of either preference or memory. Each judgment type was made under two conditions: under one condition one or the other stimulus had previously been presented subliminally, whereas under the second condition both stimuli were novel. Memory judgments were associated with activation of left frontopolar cortex and parietal areas, whereas preference judgments were associated with activation of medial prefrontal cortex and regions of occipital cortex. The modulation of preference by objective familiarity (implicit memory) was associated with right lateral frontal activation. Significant activation of hippocampal gyrus was seen in response to objective stimulus novelty, regardless of judgment type required. Our data thus demonstrate activations of a memory system independent of recollective experience. Dissociable activations within this system implicate a frontopolar involvement in explicit retrieval attempt and right lateral prefrontal cortex involvement in implicit memory expressed in preference judgments. Furthermore, the results suggest that hippocampal response to stimulus novelty can be independent of conscious reportability of familiarity.

When stimuli are presented multiple times, the neural response to repeated stimuli is reduced relative to novel stimuli (repetition suppression). Responses to different types of novelty were examined. Stimulus novelty was examined by contrasting first vs. second presentation of triads of objects during memory encoding. Semantic novelty was contrasted by comparing unrelated (semantically novel) triads of objects to triads in which all three objects were related (e.g., all objects were tools). In recognition, associative novelty was examined by contrasting rearranged triads (previously seen objects in a new association) with intact triads. Activity was observed in posterior regions (occipital and fusiform), with the largest extent of activity for stimulus novelty and smallest for associational novelty. Frontal activity was also observed in stimulus and semantic novelty. Additional analysis indicated that the hemodynamic response in voxels identified in the stimulus and semantic novelty contrasts was modulated by reaction time on a trial-by-trial basis. That is, the duration of the hemodynamic response was driven by reaction time. This was not the case for associative novelty. The high level of overlap across different forms of novelty suggests a similar mechanism for reduced neural activity, which may be related to reduced visual processing time. This is consistent with a facilitation model of repetition suppression, which posits a reduced peak and duration of neuronal firing for repeated stimuli.

Neural responses to auditory stimulus deviance under threat of electric shock revealed by spatially-filtered magnetoencephalography

The reward after-effect of effort expenditure refers to the phenomenon that previous effort investment changes the subjective value of rewards when obtained. However, the neural mechanisms underlying the after-effects of effort exertion are still not fully understood. We investigated the modulation of reward after-effects by effort type (cognitive vs. physical) through the lens of neural dynamics. Thirty-two participants performed a physically or cognitively demanding task during an effort phase and then played a simple gambling game during a subsequent reward phase to earn monetary rewards while their electroencephalogram (EEG) was recorded. We found that previous effort expenditure decreased electrocortical activity during feedback evaluation. Importantly, this effort effect occurred in a domain-general manner during the early stage (as indexed by the reward positivity) but in a domain-specific manner during the later and more elaborative stage (as indexed by the P3 and delta oscillation) of reward evaluation. Additionally, effort expenditure enhanced P3 sensitivity to feedback valence regardless of effort type. Our findings suggest that cognitive and physical effort, although bearing some surface resemblance to each other, may have dissociable neural influences on the reward after-effects.

Inferring agency: A two-stage process from early integration to late differentiation during action-outcome monitoring.

The way we view ourselves may play an important role in our responses to interpersonal interactions. In this study, we investigate how feedback valence, consistency of feedback with self-knowledge and global self-esteem influence affective and neural responses to social feedback. Participants (N = 46) with a high range of self-esteem levels performed the social feedback task in an MRI scanner. Negative, intermediate and positive feedback was provided, supposedly by another person based on a personal interview. Participants rated their mood and applicability of feedback to the self. Analyses on trial basis on neural and affective responses are used to incorporate applicability of individual feedback words. Lower self-esteem related to low mood especially after receiving non-applicable negative feedback. Higher self-esteem related to increased posterior cingulate cortex and precuneus activation (i.e. self-referential processing) for applicable negative feedback. Lower self-esteem related to decreased medial prefrontal cortex, insula, anterior cingulate cortex and posterior cingulate cortex activation (i.e. self-referential processing) during positive feedback and decreased temporoparietal junction activation (i.e. other referential processing) for applicable positive feedback. Self-esteem and consistency of feedback with self-knowledge appear to guide our affective and neural responses to social feedback. This may be highly relevant for the interpersonal problems that individuals face with low self-esteem and negative self-views.

Receiving feedback from our environment that informs us about the outcomes of our actions helps us assess our abilities (e.g., metacognition) and to flexibly adapt our behavior, consequently increasing our chances of success. However, a detailed examination of the effect of feedback on the brain activation during perceptual and confidence judgments as well as the interrelations between perceptual accuracy, prospective and retrospective confidence remains unclear. Here we used functional magnetic resonance imaging (fMRI) to examine the neural response to feedback valence and source in visual contrast discrimination together with prospective confidence judgments at the beginning of each block and retrospective confidence judgments after every decision. Positive feedback was associated with higher activation (or lower deactivation depending on the area) in areas previously involved in attention, performance monitoring and visual regions during the perceptual judgment than during the confidence judgment. Changes in prospective confidence were positively related to changes in perceptual accuracy as well as to the corresponding retrospective confidence. Thus, feedback information impacted multiple, qualitatively different brain processing states, and we also revealed the dynamic interplay between prospective, perceptual accuracy and retrospective self-assessment.

Reduced sensitivity to positive feedback is common in patients with major depressive disorder (MDD). However, findings regarding negative feedback are ambiguous, with both exaggerated and blunted responses being reported. The ventral striatum (VS) plays a major role in processing valenced feedback, and previous imaging studies have shown that the locus of controls (self agency v. external agency) over the outcome influences VS response to feedback. We investigated whether attributing the outcome to one's own action or to an external agent influences feedback processing in patients with MDD. We hypothesized that depressed participants would be less sensitive to the feedback attribution reflected by an altered VS response to self-attributed gains and losses. Using functional MRI and a motion prediction task, we investigated the neural responses to self-attributed (SA) and externally attributed (EA) monetary gains and losses in unmedicated patients with MDD and healthy controls. We included 21 patients and 25 controls in our study. Consistent with our prediction, healthy controls showed a VS response influenced by feedback valence and attribution, whereas in depressed patients striatal activity was modulated by valence but was insensitive to attribution. This attribution insensitivity led to an altered ventral putamen response for SA - EA losses in patients with MDD compared with healthy controls. Depressed patients with comorbid anxiety disorder were included. These results suggest an altered assignment of motivational salience to SA losses in patients with MDD. Altered striatal response to SA negative events may reinforce the belief of not being in control of negative outcomes contributing to a cycle of learned helplessness.

Decision-making is a fundamental aspect of human behavior, especially in uncertain situations where social interactions play a significant role. Social dominance, which involves power dynamics within groups, holds the potential to shape decision-making. Individuals’ expectations and certainty about outcomes are crucial for monitoring their performance in social dominance situations. However, the impact of expected and unexpected uncertainty on decision-making in social dominance contexts remains unclear. This study aimed to unravel the neural and behavioral patterns associated with decision-making across varying social dominance levels under conditions of uncertainty. Researchers investigated this by analyzing brain activity in 51 students. Participants were presented with both positive and negative feedback under conditions of both expectation and uncertainty, while their brain activity was recorded using electroencephalography (EEG). Specifically, we investigated the properties of key neural correlates of feedback processing, including feedback-related negativity (FRN), and P3 components of event-related potential (ERP), and reward prediction error (RPE) signals. The results revealed that the low-dominance group exhibited a larger FRN amplitude than the high-dominance group. Also, unexpected-uncertain negative feedback elicits a stronger FRN amplitude than other conditions. P3 amplitude was larger for high-dominance compared to low-dominance individuals. Additionally, P3 amplitude varied by feedback valence and condition, with larger amplitudes for positive feedback and unexpected-uncertain conditions. In FRN wave difference, the high-dominance individuals exhibited more negative amplitude in unexpected-uncertain conditions. This reveals distinct neural responses to uncertainty and feedback between individuals with high and low dominance, suggesting that social hierarchy modulates brain mechanisms underlying decision-making and reward processing.

Chasing the "Like": High FoMO elevates P300 responses to positive social feedback.

Decision-making is a fundamental aspect of human behavior, especially in uncertain situations where social interactions play a significant role. Social dominance, which involves power dynamics within groups, holds the potential to shape decision-making. Individuals' expectations and certainty about outcomes are crucial for monitoring their performance in social dominance situations. However, the impact of expected and unexpected uncertainty on decision-making in social dominance contexts remains unclear. This study aimed to unravel the neural and behavioral patterns associated with decision-making across varying social dominance levels under conditions of uncertainty. Researchers investigated this by analyzing brain activity in 51 students. Participants were presented with both positive and negative feedback under conditions of both expectation and uncertainty, while their brain activity was recorded using electroencephalography (EEG). Specifically, we investigated the properties of key neural correlates of feedback processing, including feedback-related negativity (FRN), and P3 components of event-related potential (ERP), and reward prediction error (RPE) signals. The results revealed that the low-dominance group exhibited a larger FRN amplitude than the high-dominance group. Also, unexpected-uncertain negative feedback elicits a stronger FRN amplitude than other conditions. P3 amplitude was larger for high-dominance compared to low-dominance individuals. Additionally, P3 amplitude varied by feedback valence and condition, with larger amplitudes for positive feedback and unexpected-uncertain conditions. In FRN wave difference, the high-dominance individuals exhibited more negative amplitude in unexpected-uncertain conditions. This reveals distinct neural responses to uncertainty and feedback between individuals with high and low dominance, suggesting that social hierarchy modulates brain mechanisms underlying decision-making and reward processing.

Abnormal social or reward processing is associated with several mental disorders. Although most studies examining reward processing have focused on monetary rewards, recent research also has tested neural reactivity to social rewards (e.g., positive social feedback). However, the majority of these studies only include two feedback valences (e.g., acceptance, rejection). Yet, social evaluation is rarely binary (positive vs. negative) and people often give 'on the fence' or neutral evaluations of others. Processing of this type of social feedback may be ambiguous and impacted by factors such as psychopathology, self-esteem, and prior experiences of rejection. Thus, the present study probed the reward positivity (RewP), P300, and late positive potential (LPP) following acceptance, rejection, and "one the fence" [between acceptance and rejection] feedback in undergraduate students (n = 45). Results indicated that the RewP showed more positive amplitudes following acceptance compared to both rejection and "on the fence" feedback, and the RewP was larger (i.e., more positive) following rejection relative to "on the fence" feedback. In contrast, the P300 did not differ between rejection and "on the fence" feedback, and both were reduced compared to acceptance. The LPP was blunted in response to rejection relative to acceptance and "on the fence" feedback (which did not differ from each other). Exploratory analyses demonstrated that greater self-reported rejection sensitivity was associated with a reduced LPP to acceptance. Taken together, these findings suggest that the neural systems underlying the RewP, P300, and LPP may evaluate "on the fence" social feedback differently, and that individuals high on rejection sensitivity may exhibit reduced attention toward and elaborative processing of social acceptance.