Subjects: Psychology >> Cognitive Psychology submitted time 2023-02-14
Abstract：
Under the influence of the novel coronavirus epidemic, some negative social events, such as separation of family or friends and home isolation have increased. These events can cause negative emotion experiences similar to physical pain, thus they are called social pain. Placebo effect refers to the positive response to the inert treatment with no specific therapeutic properties, which has been shown to be one of the effective ways to alleviate social pain. Studies have shown that the dorsolateral prefrontal cortex (DLPFC) plays a key role in placebo effect. Therefore, this study aimed to explore whether activating DLPFC by using transcranial magnetic stimulation (TMS) could improve the ability of placebo effects to regulate social pain. Besides, we also combined neuroimaging and neuromodulation techniques to provide bidirectional evidence for the role of the DLPFC on placebo effects. We recruited a total of 100 participants to finish the task of negative emotional rating of the social exclusion images. Among them, 50 participants were stimulated by TMS at the right DLPFC (rDLPFC), while the others were assigned to the sham group. This study contained two independent variables. The between-subject variable was TMS group (rDLPFC-activated group or sham group) and the within-subject variable was placebo type (no-placebo and placebo). All participants received nasal spray in two blocks. In the no-placebo condition, participants were instructed that they would receive a saline nasal spray which helped to improve physiological readings; in placebo block, participants were told to administrate an intranasal fluoxetine spray (saline nasal spray in fact) that could reduce unpleasantness within 10 minutes. To strengthen the expectation of intranasal fluoxetine, participants viewed a professional introduction to fluoxetine’s clinical and academic usage including downregulating negative emotion, such as fear, anxiety, and disgust. Participants who received the placebo block first would be reminded that fluoxetine’s effect was over before the next block to reduce the carry-over for the following block. Self-reported negative emotional and electroencephalogram data were recorded. There was a significant two-way interaction of TMS group and placebo type. Results showed that compared with the sham group, participants in the rDLPFC-activated group reported less negative emotional feeling and had a lower amplitude of the late positive potential (LPP) in placebo condition, a component that reflects the emotional intensity, suggesting that activating rDLPFC can improve the ability of placebo effect to regulate social pain. The above finding suggested that activating DLPFC can improve the placebo effect of regulating negative emotion. Moreover, this study is the first attempt to investigate the enhancement of placebo effects by using TMS on emotion regulation. The findings not only support the critical role of DLPFC on placebo effect using neuroimaging and neuromodulation techniques, but also provide a potential brain target for treating emotional regulation deficits in patients with psychiatric disorders.
Peer Review Status:
Awaiting Review
Subjects: Psychology >> Developmental Psychology submitted time 2022-12-26
Abstract：
People tend to give priority to negative information and allocate more cognitive resources such as perception, attention and memory to negative, compared to positive, information. This phenomenon is called "negativity bias", which is well established across toddlers, children, adolescents and adults. However, this emotional bias remains controversial in infants, especially in young infants that are less than six months old. Furthermore, it is still unclear whether the emotional bias changes from no bias or positivity bias to negativity bias during infants’ development in the first year of life. In this study, we used near-infrared spectroscopy to examine the neural responses to angry and happy prosodies in 45 neonates (0 month old) and 45 infants (one year old). The experiment was conducted in the neonatal ward of Peking University First Hospital. NIRS data were recorded when the infants were at active sleeping or staying quietly. Using a passive listening task, we investigated the brain functional connectivity during automatic processing of emotional prosodies of anger and happiness. The experiment was divided into three emotional blocks (using angry, happy and neutral prosodies, respectively). The order of the three blocks was counterbalanced among the participants. Each block contained 10 sentences, which were repeated six times, that is, 60 sentences were presented during the experiment in a random order. The results showed that emotion category had a significant main effect on 60 pairs of functional connectivity, which revealed that angry and happy prosodies evoked stronger functional connectivity than neutral prosody, whereas there was no significant difference between the angry and happy conditions. The observed significant functional connectivity was mainly distributed within the right hemisphere or across bilateral hemispheres. More importantly, there was an interaction between emotion category and group in the functional connectivity of frontal, temporal and parietal lobe of the right hemisphere. In the neonate group, the functional connectivity in the happy prosody condition was stronger than that in the angry prosody condition. By contrast, the functional connectivity in the infant group showed stronger connectivity in the angry compared to the happy condition. By examining the neural response to emotional prosodies at two time points (0 and 1 year old), this study revealed for the first time the changes of emotional bias in a developmental perspective. We found that emotional processing has a positive bias at the beginning of postnatal period, revealed by the stronger functional connectivity for happy than for angry prosodies at the right hemisphere of the superior temporal gyrus, the inferior frontal gyrus, the supramarginal gyrus, and the angular gyrus. However, the emotional processing bias reverses in 1-year-old infants, that is, the brain functional connectivity within the above mentioned brain regions is stronger for angry than that for happy prosodies. Therefore, the reliable phenomenon of "negativity bias" is not innate, although it is always observed in adults and children. Instead, we propose that there is a developmental change from positivity bias to negativity bias in the first year of human life.
Peer Review Status:Awaiting Review
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