Subjects: Psychology >> Social Psychology submitted time 2023-03-27 Cooperative journals: 《心理学报》
Abstract： Emotion regulation is crucial to mental health and social life. Traditional view conceived emotion regulation as a deliberative process. However, there is growing evidence that emotion regulation can implement at an implicit level without or with limited involvement of the lateral prefrontal cortex (LPFC) that is responsible for cognitive control. Unlike explicit emotion regulation, we have few knowledge on the neural mechanisms underlying implicit emotion regulation. Here, we investigated the effect of excitatory the ventromedial prefrontal cortex (vmPFC) using transcranial direct current stimulation (tDCS) to provide causal evidence for the key role of the vmPFC in implicit emotion regulation. This study had a mixed design, with group (anodal vs. sham) as the between-subject factor and priming type (reappraisal vs. baseline) as the within-subject factor. A total of 80 participants were recruited and randomly assigned to the anodal group and the sham tDCS group. The task was divided into two blocks, i.e., the implicit reappraisal block and the baseline block. The order of the two blocks was counterbalanced within the participants in each group. At the beginning of each block, participants were required to complete a tDCS session (1.5 mA; 10 min for the active group and 1 min for the sham group). The anodal electrode was placed in the middle of Fz and Fpz and the ground electrode was placed under the chin). Then, participants completed six sessions of sentence unscramble task (10 trials per session) to prime the emotion regulation goal. Each session of the sentence unscramble task was followed by a picture viewing task (5 trials) to evoke negative emotions. The self-reported emotion rating and EEG signals were recorded during the picture viewing task. Half an hour after the end of the picture viewing task, participants were asked to rate the valence (1 = very unpleasant; 9 = very pleasant) of all viewed images in the picture viewing task. The results showed that the experimental group (n = 40) reported lower negative emotional experience and showed lower LPP amplitudes (measured as the average amplitude of Pz P3, P4, CP1, CP2) when the vmPFC was activated in the cognitive reappraisal block compared to the control group (n = 40), indicating that excitatory vmPFC could effectively facilitate the ability of implicit emotion regulation. Furthermore, we also found that excitatory vmPFC can reduce the P1 amplitude (measured as the average amplitude of O1, O2) under both baseline and reappraisal conditions. The above results indicated that activating the vmPFC could not only facilitate implicit emotion regulation but also reduce early attention distribution to negative stimuli. This study is the first attempt to use the tDCS technique to investigate priming-induced implicit emotion regulation. The results directly reveal the causal relationship between the vmPFC and implicit cognitive reappraisal, suggesting this brain region as a potential target of neural modulation to enhance the ability of implicit emotion regulation in clinical populations.
Subjects: Psychology >> Social Psychology submitted time 2023-03-27 Cooperative journals: 《心理学报》
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.
Subjects: Psychology >> Social Psychology submitted time 2023-03-27 Cooperative journals: 《心理学报》
Abstract： Depression is a common mental disorder characterized by persistent low mood and anhedonia. While healthy people can voluntarily forget unpleasant events, depressed patients cannot or have difficulty in forgetting negative stimuli. Studies focused on healthy population have found that memory suppression is not only associated with decreased neural activation in the hippocampus, but also significantly activates a wide network in the prefrontal cortex, especially the right dorsolateral prefrontal cortex (DLPFC). Meanwhile, studies have demonstrated that depressed participants could not effectively recruit their frontal brain network responsible for inhibition control of negative materials. Thus, the key question of this study is to examine whether an enhancement of the neural activation in DLPFC using transcranial magnetic stimulation (TMS) could improve the ability of voluntary forgetting of negative information in depressed patients. We recruited a total of 123 participants. Among them, 31 healthy participants were stimulated by TMS at the right DLPFC (right DLPFC-activated controls), 32 patients and 30 patients were stimulated by TMS at the left and right DLPFC respectively (left and right DLPFC-activated patients). The other 30 patients were assigned into a sham TMS group. This study contained three independent variables. The two within-subject variables were TMS (baseline or TMS condition) and directed forgetting instruction (remember or forget), and the between-subject variable was group (left or right DLPFC-activated patient, or right DLPFC-activated control). We focused on the memory suppression of social feedbacks in this study, since social feedback processing plays a vital role in everyday interpersonal activities. Previous studies have found that depressed patients cannot perceive and evaluate social feedbacks accurately and adaptively, which makes negative social experiences being an important inducing factor of depression. Meanwhile, evidence indicates that depressed patients have more deficits in processing social relative to nonsocial information. Results of the explicit memory test showed that the recall accuracy of social rejection was higher in patients than healthy controls in baseline condition, suggesting that patients had difficulty in voluntarily forgetting negative social feedback. After we used the TMS to activate the left or right DLPFC of participants, we found no significant difference in the recall accuracy of social rejection between the three groups. This result suggested that the ability of memory suppression for negative social feedback was improved by TMS in patients. Moreover, it was also found that patients rated the feedback senders as being more attractive after they had forgotten negative social feedback provided by these feedback senders. The main contribution of this study is that we first attempt to improve the ability of memory suppression of negative information in depressed patients using the TMS technique. Still now, there have been only two neuroscience studies focusing on the deficits of directed forgetting in depression ( Xie, Jiang, & Zhang, 2018; Yang et al., 2016). Beyond these two studies, we demonstrated a causal relationship between the DLPFC and memory suppression impairment in depressed patients by employing TMS to facilitate the function of DLPFC. Thus, we provide a potential neural target for the clinical treatment of depressed patients with voluntary forgetting deficits. In addition to depression, difficulties in voluntary forgetting is a common problem found in patients diagnosed with post-traumatic stress disorder, anxiety disorder (including obsessive compulsive disorder), schizophrenia and many other mental disorders. Meanwhile, difficulties in forgetting the euphoria or enjoyment coming from drugs or high-calorie foods might be an important reason for the persistence and aggravation of drug addiction and bulimia. Our finding suggests that the right DLPFC may be a potential brain target for the treatment of memory suppression deficits in these disorders. Facilitating the cognitive control of this brain region using the TMS is expected to restore the inhibitory control function of patients and thus significantly improve their voluntary forgetting ability, helping them to relieve symptoms and recover from disorders.
Subjects: Psychology >> Social Psychology submitted time 2023-03-27 Cooperative journals: 《心理学报》
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.
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