The neural signatures of egocentric bias in normative decision-making.

Bargaining parties often disagree on what fair is, due to the reason that people are prone to believe that what favors oneself is fair, i.e., an egocentric bias. In this study, we investigated the neural signatures underlying egocentric bias in fairness decision-making, conjoining an adapted ultimatum game (UG) with event-related fMRI and functional connectivity. Participants earned monetary rewards with a partner in a production stage, wherein their contributions to the earnings were manipulated. Afterwards, the joint earnings were randomly divided, and the distribution was presented simultaneously with contribution information to participants, who accepted/rejected distributions of earnings as the same manner in standard UG. We identified an egocentric bias in fairness decisions, such that participants frequently rejected self-contributed disadvantageous outcomes, but much less so in response to other-contributed advantageous outcomes, although both involved mismatch between contribution and payoff. This bias was underpinned by regions involved in representing fairness norms, including the anterior insula and dorsal anterior cingulate cortex (dACC). Furthermore, the thalamus activity was predictive of the bias, such that the level of egocentric bias decreased as a function of the activation level of the thalamus. Finally, our functional-connectivity findings indicated that the thalamus worked together with insula and dACC to modulate behavioral egocentric bias in fairness-related decisions. Our findings uncover the neural basis underlying the modulation of egocentric bias in normative decision-making, and highlight the role of neural circuits associated with norm enforcement in this phenomenon.

Social hierarchy modulates neural responses of empathy for pain.

Recent evidence indicates that empathic responses to others' pain are modulated by various situational and individual factors. However, few studies have examined how empathy and underlying brain functions are modulated by social hierarchies, which permeate human society with an enormous impact on social behavior and cognition. In this study, social hierarchies were established based on incidental skill in a perceptual task in which all participants were mediumly ranked. Afterwards, participants were scanned with functional magnetic resonance imaging while watching inferior-status or superior-status targets receiving painful or non-painful stimulation. The results revealed that painful stimulation applied to inferior-status targets induced higher activations in the anterior insula (AI) and anterior medial cingulate cortex (aMCC), whereas these empathic brain activations were significantly attenuated in response to superior-status targets' pain. Further, this neural empathic bias to inferior-status targets was accompanied by stronger functional couplings of AI with brain regions important in emotional processing (i.e. thalamus) and cognitive control (i.e. middle frontal gyrus). Our findings indicate that emotional sharing with others' pain is shaped by relative positions in a social hierarchy such that underlying empathic neural responses are biased toward inferior-status compared with superior-status individuals.

How does experience modulate auditory spatial processing in individuals with blindness?

Comparing early- and late-onset blindness in individuals offers a unique model for studying the influence of visual experience on neural processing. This study investigated how prior visual experience would modulate auditory spatial processing among blind individuals. BOLD responses of early- and late-onset blind participants were captured while performing a sound localization task. The task required participants to listen to novel "Bat-ears" sounds, analyze the spatial information embedded in the sounds, and specify out of 15 locations where the sound would have been emitted. In addition to sound localization, participants were assessed on visuospatial working memory and general intellectual abilities. The results revealed common increases in BOLD responses in the middle occipital gyrus, superior frontal gyrus, precuneus, and precentral gyrus during sound localization for both groups. Between-group dissociations, however, were found in the right middle occipital gyrus and left superior frontal gyrus. The BOLD responses in the left superior frontal gyrus were significantly correlated with accuracy on sound localization and visuospatial working memory abilities among the late-onset blind participants. In contrast, the accuracy on sound localization only correlated with BOLD responses in the right middle occipital gyrus among the early-onset counterpart. The findings support the notion that early-onset blind individuals rely more on the occipital areas as a result of cross-modal plasticity for auditory spatial processing, while late-onset blind individuals rely more on the prefrontal areas which subserve visuospatial working memory.

Chinese herbal medicine and cognitive and emotional functions during 60-day head-down bed rest.

INTRODUCTION: This study aimed to test the efficacy of an oral-intake Chinese herbal medicine in enhancing the cognitive and emotional functions of individuals in a simulated microgravity condition. The herbal medicine consisted of ingredients that may enhance cognitive and emotional functions in an extreme environment. METHODS: There were 14 healthy male subjects who were randomly assigned to a Chinese medicine (CMG) or a control (CG) group and underwent a 60-d 6 degree head-down bed-rest protocol. Testing was conducted before (Day -3), throughout (Days 3, 7, 20, 40, 57), and after (Days +3, +10) the bedrest protocol. The Arrow Test, Balloon Analog Risk Task (BART), Dual Task, and Affect Grid were administered on all testing days. RESULTS: The CMG demonstrated consistently higher scores on the BART (Days 20 to 40; Mean: CMG, 43.0 to 46.2 and CG, 30.2 to 25.5) and lower levels of arousal on the Affect Grid (Days 7 to 40; Mean: CMG, 6.9 to 6.7 and CG, 8.1 to 8.0) than did the CG. The CMG showed significantly higher performance on the Arrow Test (incompatible condition) at the beginning of the bed-rest period (Day 3 to 7; Mean: 799.5 ms and 763.1 ms, respectively) which was not observed in the CG. DISCUSSIONS: Results suggest that the Chinese herbal medicine may calm subjects' emotions by lowering the arousal level. At the same time, it may have produced positive effects in enhancing advantageous risk-taking and to a lesser extent self-regulatory behaviors (in the early phase).

Effects of discrepancy between imagined and perceived sounds on the N2 component of the event-related potential.

Two experiments were conducted to examine whether the N2 component of the event-related potential (ERP), typically elicited in a S1-S2 matching task and considered to reflect mismatch process, can still be elicited when the S1 was imagined instead of perceived and to investigate how N2 amplitude varied with the degree of S1-S2 discrepancy. Three levels of discrepancy were defined by the degree of separation between the heard (S2) and imagined (S1) sounds. It was found that the N2 was reliably elicited when the perceived S2 differed from the imagined S1, but whether N2 amplitude increased with the degree of discrepancy depended in part on the S1-S2 discriminability (as evidenced by reaction time). Specifically, the effect of increasing discrepancy was attenuated as discriminability increased from hard to easy. These results, together with the dynamic ERP topography observed within the N2 window, suggest that the N2 effect reflects two sequential but overlapping processes: automatic mismatch and controlled detection.

Neural correlates of traditional Chinese medicine induced advantageous risk-taking decision making.

This fMRI study examined the neural correlates of the observed improvement in advantageous risk-taking behavior, as measured by the number of adjusted pumps in the Balloon Analogue Risk Task (BART), following a 60-day course of a Traditional Chinese Medicine (TCM) recipe, specifically designed to regulate impulsiveness in order to modulate risk-taking behavior. The 14 participants recruited for this study were randomly assigned to the experimental and control groups and the TCM recipe (Panax, 520 mg; Astragalus membranaceous Bunge, 520 mg; Masnetitum, 840 mg; Ostrea gigas Thumb, 470 mg; Thinleaf Milkwort Root Radix Polygalae, 450 mg; and Os Draconis, 470 mg) was administered, as a diet supplement, to the seven participants in the experimental group. The neural activity of the two groups was monitored by a 3T MRI scanner, before and after the 60-day treatment. Associated with the improved advantageous risk-taking behavior seen in the experimental group, significantly stronger blood oxygenation level dependent (BOLD) responses were observed in the bilateral dorsolateral prefrontal cortex (DLPFC), left putamen, left thalamus, right insula, and right anterior cingulate cortex (ACC), regions which have previously been reported as being involved in risk-taking decision making. The effect of the TCM in improving advantageous risk-taking decision making appears to have been related to the enhanced efficiency of the cognitive affective system, the PFC-ACC-insula-striatum network, which functions to inhibit impulsiveness, to sensitize reward-related information, and to allow the opportunity, during risk estimation, to evaluate potential gains and losses. The findings of this study suggest that interventions acting on factors modulating risk-taking decision making could have a beneficial effect in terms of optimizing risk-taking behavior.

Dissociable pitch processing mechanisms in lexical and melodic contexts revealed by ERPs.

The current ERP study examined the neural substrates for pitch processing in music and in tonal language with phrases ending in either congruous or incongruous pitches. In a tonal language, like Chinese, pitch is lexically relevant as it can change the meaning of words, and it could therefore be hypothesized that pitch information under this condition is processed differently from musical pitch. Female Chinese musicians were chosen as listeners for their ample exposure to music and a tonal language. Pitch violations in both domains were associated with a frontally distributed late positive component (LPC). In addition to evoking an N400 for language condition, pitch processing as revealed by the LPCs is left lateralized for tonal language and right lateralized for music. We propose that our data may imply different brain resources engaging in pitch processing depending on whether its function is lexical, as in a tonal language like Chinese, or musical in nature.

Auditory-induced emotion modulates processes of response inhibition: an event-related potential study.

This study investigated the impact of auditory-induced emotion on response inhibition. Fifty kinds of positive, neutral, and negative sounds were used as emotional materials whose presentation was followed by a Go/Nogo task. Event-related potentials were recorded for Go and Nogo tones. The response times for Go stimuli were longer under negative than under positive and neutral emotions. In addition, Go and Nogo stimuli elicited larger N1 amplitudes during neutral than during emotional conditions. Moreover, Nogo-related N2 was larger for neutral sounds than for positive and negative sounds. The Nogo-N2, however, was not different between positive and negative sounds. Therefore, auditory-induced emotions significantly modulated the behavioral performance and the process of response conflict monitoring, a central component to the activity of response inhibition.