Blinding integrity of dorsomedial prefrontal intermittent theta burst stimulation in depression

BackgroundThe antidepressant effect of repetitive transcranial magnetic stimulation (rTMS) is partly placebo, making blinding integrity important. Blinding of high-frequency rTMS and intermittent theta burst stimulation (iTBS) has been reported as successful at study end. However, blinding integrity at study start is rarely reported. The aim of this study was to investigate blinding integrity during a treatment course of iTBS over the dorsomedial prefrontal cortex (DMPFC) in depression.MethodsForty-nine patients with depression from a double-blind-designed randomized controlled trial (NCT02905604) were included. Patients received either active or sham iTBS over the DMPFC with a placebo coil. The sham group received iTBS-synchronized transcutaneous electrical nerve stimulation.ResultsAfter one session, 74% of participants were able to correctly guess their treatment allocation. This was above chance level (p = 0.001). The percentage dropped to 64% and 56% after the fifth and last sessions. Belonging to the active group influenced the choice to guess “active” (odds ratio: 11.7, 95% CI 2.5–53.7). A higher treatment intensity of the sham treatment increased the probability to guess “active”, but pain did not influence the choice.ConclusionsBlinding integrity in iTBS trials must be investigated at study start to avoid uncontrolled confounding. Better sham methods are needed.     

Dorsolateral prefrontal cortex mediates working memory processes in motor skill learning

Neuroimaging studies have shown that the dorsolateral prefrontal cortex (DLPFC) is recruited during motor skill learning, which suggests the involvement of the DLPFC in working memory (WM) processes, such as selection and integration of motor representations temporarily stored in WM. However, direct evidence linking activation of the DLPFC to WM storage and manipulation during motor skill learning in real-time is rare. In this study, we conducted two experiments to investigate the causal role of DLPFC activity in WM storage and manipulation during motor skill learning under low and high WM-demand conditions. Participants received continuous theta burst stimulation (cTBS) and sham stimulation (crossover design) over the left DLPFC (experiment 1) or right DLPFC (experiment 2). Before and after stimulation, participants in both experiments performed a sequential finger-tapping (SFT) task containing repeated sequence (low-WM demand) and non-repeated sequence (high-WM demand) conditions which are used to study WM processes. The number of correct sequences (NoCS) and reproduction error rate were analyzed. Learning gains in NoCS improved significantly with the practice for both sequence types in the presence of either stimulation type. Compared to sham stimulation, cTBS over the left DLPFC resulted in significantly reduced learning gains in NoCS for non-repeated sequences. These results suggest that the left DLPFC contributes to WM manipulation during motor skill learning.     

Transcranial direct current stimulation versus intermittent theta-burst stimulation for the improvement of working memory performance

Non-invasive brain stimulation (NIBS) techniques have been increasingly used over the dorsolateral prefrontal cortex (DLPFC) to enhance working memory (WM) performance. Notwithstanding, NIBS protocols have shown either small or inconclusive cognitive effects on healthy and neuropsychiatric samples. Therefore, we assessed working memory performance and safety of transcranial direct current stimulation (tDCS), intermittent theta-burst stimulation (iTBS), and both therapies combined vs placebo over the neuronavigated left DLPFC of healthy participants. Twenty-four subjects were included to randomly undergo four sessions of NIBS, once a week: tDCS alone, iTBS alone, combined interventions and placebo. The 2-back task and an adverse effect scale were applied after each NIBS session. Results revealed a significantly faster response for iTBS (b= -21.49, p= 0.04), but not for tDCS and for the interaction tDCS vs. iTBS (b= 13.67, p= 0.26 and b= 40.5, p= 0.20, respectively). No changes were observed for accuracy and no serious adverse effects were found among protocols. Although tolerable, an absence of synergistic effects for the combined protocol was seen. Nonetheless, future trials accessing different outcomes for the combined protocols, as well as studies investigating iTBS over the left DLPFC for cognition and exploring sources of variability for tDCS are encouraged.     

Effects of tDCS over the right DLPFC on attentional disengagement from positive and negative faces: An eye-tracking study

The aim of this study was to increase insight in the neural substrates of attention processes involved in emotion regulation. The effects of right dorsolateral prefrontal cortex (i.e., DLPFC) stimulation on attentional processing of emotional information were evaluated. A novel attention task allowing a straightforward measurement of attentional engagement toward, and attentional disengagement away from emotional faces was used. A sample of healthy participants received 20 minutes of active and sham anodal transcranial direct current stimulation (i.e., tDCS) applied over the right DLPFC on 2 separate days and completed the attention task after receiving real or sham stimulation. Compared to sham stimulation, tDCS over the right DLPFC led to impairments in attentional disengagement from both positive and negative faces. Findings demonstrate a causal role of right DLPFC activity in the generation of attentional impairments that are implicated in emotional disturbances such as depression and anxiety.     

Stomaching rejection: Self-compassion and self-esteem moderate the impact of daily social rejection on restrictive eating behaviours among college women

Objective: The present study examined whether having high self-esteem or a self-compassionate perspective help mitigate the impact of daily social rejection on negative affect and restrictive eating behaviours.

Design: Following a baseline survey assessing self-esteem and self-compassion, 121 college women completed online daily diaries for one week.

Main Outcome Measures: Negative affect and restrictive eating behaviours.

Results: On days when women reported more rejection, they also reported higher restrictive eating behaviours and greater negative affect. Effects were moderated by self-esteem and self-compassion, such that the lower participants were in self-esteem or self-compassion, the stronger the positive relation between rejection and negative affect and restrictive eating. However, only the common humanity/isolation dimension of self-compassion significantly moderated daily effects of rejection when controlling for self-esteem. Mediated moderation results reveal different mechanisms by which self-esteem and self-compassion buffer against rejections’ effects on affect and restrictive eating.

Conclusion: Self-compassion and self-esteem influence the complex impact that social rejection has on affect and restrictive eating. More than other dimensions of self-compassion or self-esteem, remembering one’s common humanity can result in a healthier response to social rejection.     

Alteration of hypnotic experience following transcranial electrical stimulation of the left prefrontal cortex

BackgroundRecent studies of neurostimulation reported alteration of hypnotizability and hypnotic phenomena after inhibition of the dorsolateral prefrontal cortex (DLPFC), but the different assessments of hypnosis and the stimulation parameters still left open many questions about the role of this brain region in hypnotizability. We aimed to administer inhibitory transcranial direct current stimulation (tDCS) over the left DLPFC to observe effects of stimulation on the hypnotic experience and the feeling of agency.Methodsa procedure of hypnotic induction with suggestions was repeated twice: before and after the unilateral cathodal tDCS over the left DLPFC. The experience was assessed through a phenomenological assessment of hypnosis and sense of agency in thirty-three participants randomly assigned to the sham or the active group.Resultsactive (inhibitory) tDCS enhanced the hypnotizability by 15.4% and altered a few dimensions of consciousness such as self-awareness and absorption. No changes emerged on the feeling of agency and pass rates for suggestions.ConclusionstDCS reflects a promising tool to alter the hypnotic phenomena and the responsiveness to hypnotic procedures. Neurocognitive implications are discussed for the construct of hypnotizability as well as for the role of the left DLPFC in the dimensions of consciousness such as self-awareness.     

The contribution of self-compassion in the relationship between social support and posttraumatic growth

IntroductionDespite well-established evidence on the relationship between social support and posttraumatic growth (PTG), there remains a paucity of evidence regarding the mechanism that underlie this relationship.ObjectiveThis study examined the relationship between social support and PTG, while exploring self-compassion as an intermediatory factor in this association.MethodA cross-sectional study with 447 college students was conducted in Trabzon, Turkey. The data were analyzed using Structural Equation Modelling (SEM).ResultsResults indicated that perceived social support and self-compassion were associated with PTG. Furthermore, a significant indirect effect between social support and PTG via self-compassion emerged.ConclusionBased on the study findings, tailored intervention programs targeting self-compassion and perceived social support in trauma-exposed young adults may be useful for promoting posttraumatic growth.     

Enhancing Creativity With Combined Transcranial Direct Current and Random Noise Stimulation of the Left Dorsolateral Prefrontal Cortex and Inferior Frontal Gyrus

Creativity is a fundamental human accomplishment from scientific advances to composing music. The left dorsolateral prefrontal cortex (DLPFC) and inferior frontal gyrus (IFG) are important metacontrol hubs in flexibility and persistence brain states, respectively. Those hubs are related to divergent thinking, insight problem-solving, and convergent thinking. In this double-blind, between-subjects study, 81 healthy participants were randomly assigned to one of three groups (n = 27) that received a combined transcranial direct current stimulation–transcranial random noise stimulation (tDCS-tRNS) protocol with the anode over the left DLPFC and cathode over the left IFG (+DLPFC−IFG), the opposite montage (−DLPFC+IFG), and a sham group (+DLPFC−IFG). Both active tDCS-tRNS groups received 20 min of 1 mA tDCS with 1 mA (100–500 Hz) tRNS. Creativity was assessed before (baseline) and during stimulation with the Unusual Uses, Picture Completion (PC), Remote Association test (RAT), Matchstick Arithmetic (MA), and Nine-dot (ND) problems. Only the +DLPFC−IFG group had significantly higher scores compared with sham in the RAT (p = .009), PC fluency (p = .018), PC originality (p = .007), ND (p = .007), and MA (p = .032). Overall, −DLPFC+IFG had greater scores in all creativity tests compared with sham. Implications from the metacontrol theory are discussed.     

Self-compassion induction enhances recovery from social stressors: Comparing adults with social anxiety disorder and healthy controls

Background and objectives: This study evaluates the process and consequence of inducing self-compassion during recovery from social performance stressors. Though interest in self-compassion as an intervention target is growing, extant findings suggest that initially cultivating self-compassion can be challenging for those with high self-criticism and anxiety, common features of social anxiety disorder (SAD).

Design: Quasi-experimental design.

Methods: The current study evaluates the feasibility, content, and outcomes of a brief written self-compassion induction administered after consecutive laboratory social stressors, among adults with SAD (n?=?21) relative to healthy controls (HC; n?=?35).

Results: Findings demonstrate the feasibility of employing a written self-compassion induction among adults with (and without) SAD, reveal group differences in written responses to the induction, and suggest that the SAD group benefitted more from the induction than the HC group, based on greater reductions in state anxiety and greater increases in self-compassion during stressor recovery. Greater use of negative affect words within written responses to the self-compassion induction, but not during general writing, predicted lower subsequent state anxiety across groups, by a medium effect size.

Conclusions: Collectively, the findings support the feasibility and utility of cultivating self-compassion among adults with SAD.     

Self-compassion,social rank,and psychological distress in athletes of varying competitive levels

BackgroundSelf-Compassion may be seen as a concept contrary to the aims of athletes engaged in competitive sport. This could be accentuated at more elite levels, where athletes may view concepts like self-criticism and self-judgement as more important for improvement.ObjectivesThe current study aimed to better understand how athletes of different competitive levels (from social to international) relate to concepts of self-compassion. Further, we aimed to explore how factors relating to social rank and self-compassion contribute to psychological distress.DesignCross-sectional online survey.MethodAn online survey was distributed, including the following validated questionnaires: Depression Anxiety and Stress Scales, the Self-Compassion Scale, Fears of Compassion Scales, Social Comparison Scale, Forms of Self-Criticising/Attacking & Self-Reassuring Scale, and the Striving to Avoid Inferiority Scale.ResultsTwo hundred and fifty-three participants responded to the survey, including 115 recreational and 79 competitive athletes. There were no differences between groups on any measure of compassion or social rank. In a multiple linear regression model, lower self-compassion, higher fears of compassion (for self), and higher feelings of inadequacy predicted more pronounced psychological distress in athletes.ConclusionsContrary to expectation, the results suggest that even highly elite athletes may be open to using self-compassion. Given that reduced self-compassion and sense of social rank contributed to psychological distress in athletes, the results suggest that compassion-based approaches to treating psychological distress in this population may be valid.     

Self-compassion and social anxiety disorder

Abstract

Self-compassion refers to having an accepting and caring orientation towards oneself. Although self-compassion has been studied primarily in healthy populations, one particularly compelling clinical context in which to examine self-compassion is social anxiety disorder (SAD). SAD is characterized by high levels of negative self-criticism as well as an abiding concern about others’ evaluation of one's performance. In the present study, we tested the hypotheses that: (1) people with SAD would demonstrate less self-compassion than healthy controls (HCs), (2) self-compassion would relate to severity of social anxiety and fear of evaluation among people with SAD, and (3) age would be negatively correlated with self-compassion for people with SAD, but not for HC. As expected, people with SAD reported less self-compassion than HCs on the Self-Compassion Scale and its subscales. Within the SAD group, lesser self-compassion was not generally associated with severity of social anxiety, but it was associated with greater fear of both negative and positive evaluation. Age was negatively correlated with self-compassion for people with SAD, whereas age was positively correlated with self-compassion for HC. These findings suggest that self-compassion may be a particularly important target for assessment and treatment in persons with SAD.     

第三方惩罚的神经机制：来自经颅直流电刺激的证据

第三方惩罚既是社会规范在群体得以维系的基石, 也是个体维护社会规范的体现。当前关注社会规范的神经研究大多基于第二方惩罚的独裁者或最后通牒实验框架, 缺乏对第三方维护社会规范过程中相关脑区活动的探索, 对这一过程的内在神经机制也不清楚。本文基于第三方惩罚的独裁者博弈框架, 对右侧背外侧前额叶区域(DLPFC)进行不同极性的经颅直流电刺激(tDCS), 同时依据第三方是否需要为其惩罚付出成本设计了零成本和有成本两个实验任务。结果发现, 第三方在零成本任务的情绪反应和惩罚显著受到tDCS设置的影响, 且阴极刺激显著提升了第三方的惩罚值, 这表明情绪机制对第三方惩罚有着重要影响。另外, 第三方在零成本和有成本任务中的惩罚差异在不同tDCS设置之间也存在显著差异, 这与第三方惩罚还受到自利机制影响的观点相符。本文率先为右侧DLPFC活动影响第三方惩罚提供了神经层面的证据, 且支持了第三方对社会规范的遵从与其负性情绪反应和自利加工密切相关的机制解释。     

背外侧前额叶对主动遗忘负性社会反馈的作用：针对抑郁症的TMS研究

抑郁症患者的负性心境可能源于其抑制功能障碍。患者在主动遗忘负性材料时无法有效调用背外侧前额叶(the dorsolateral prefrontal cortex, DLPFC)等负责抑制控制的额叶脑网络。同时, 患者对社会信息的加工比对非社会信息的加工存在更明显的认知神经障碍, 很难主动遗忘对自己不利的社会反馈信息。为了提高抑郁症患者对负性社会反馈的主动遗忘能力, 本研究采用经颅磁刺激技术(transcranial magnetic stimulation, TMS), 考察抑郁症患者在左侧(n = 32)或右侧DLPFC (n = 30)被激活后其记忆控制能力的改变。结果表明, 当患者的DLPFC被TMS激活时, 他们对社会拒绝的回忆正确率与健康对照组(n = 31)无差异, 且TMS激活右侧DLPFC还改善了患者对他人的社会态度。本研究是采用TMS提高抑郁症患者主动遗忘能力的首次尝试, 研究结果不但支持了DLPFC与记忆控制功能的因果关系, 还为临床治疗抑郁症、创伤后应激障碍、药物成瘾等患者的记忆控制缺陷提供了明确的神经靶点。     

Self-compassion and responses to negative social feedback: The role of fronto-amygdala circuit connectivity

ABSTRACT

Self-compassion has been shown to have significant relationships with psychological health and well-being. Despite the increasing growth of research on the topic, no studies to date have investigated how self-compassion relates to neural responses to threats to the self. To investigate whether self-compassion relates to threat-regulatory mechanisms at the neural level of analysis, we conducted a functional MRI study in a sample of college-aged students. We hypothesized that self-compassion would relate to greater negative connectivity between the ventromedial prefrontal cortex (VMPFC) and amygdala during a social feedback task. Interestingly, we found a negative correlation between self-compassion and VMPFC-amygdala functional connectivity as predicted; however, this seemed to be due to low levels of self-compassion relating to greater positive connectivity in this circuit (rather than high levels of self-compassion relating to more negative connectivity). We also found significant relationships with multiple subcomponents of self-compassion (Common Humanity, Self-Judgment). These results shed light on how self-compassion might affect neural responses to threat and informs our understanding of the basic psychological regulatory mechanisms linking a lack of self-compassion with poor mental health.     

Noninvasive brain stimulation over M1 and DLPFC cortex enhances the learning of bimanual isometric force control

Motor learning plays an important role in upper-limb function and the recovery of lost functionality. This study aimed to investigate the relative impact of transcranial direct current stimulation (tDCS) on learning in relation to the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) during bimanual isometric force-control tasks performed with both hands under different task constraints. In a single-blind cross-over design, 20 right-handed participants were randomly assigned to either the M1 group (n = 10; mean age, 22.90 ± 1.66 years, mean ± standard deviation) or the DLPFC group (n = 10; mean age, 23.20 ± 1.54 years). Each participant received 30 min of tDCS (anodal or sham, applied randomly in two experiments) while performing the bimanual force control tasks. Anodal tDCS of the M1 improved the accuracy of maintenance and rhythmic alteration of force tasks, while anodal tDCS of the DLPFC improved only the maintenance of the force control tasks compared with sham tDCS. Hence, tDCS over the left M1 and DLPFC has a beneficial effect on the learning of bimanual force control.     

The influence of theta transcranial alternating current stimulation (tACS) on working memory storage and processing functions

The study aimed to explore the role of the fronto-parietal brain network in working memory function—in temporary storage and manipulation of information. In a single blind sham controlled experiment 36 respondents solved different working memory tasks after theta transcranial alternating current stimulation (tACS) was applied to left frontal, left parietal and right parietal areas. Both verum tACS protocols stimulating parietal brain areas (target electrodes positioned at location P3, or P4) had a positive effect on WM storage capacity as compared with sham tACS, whereas no such influence was observed for the stimulation of the left frontal area (target electrode positioned at location F3). A second finding was that left parietal theta tACS had a more pronounced influence on backward recall than on forward recall, which was not related to task content (spatial or verbal). The influence of theta tACS on WM executive processes was most pronounced for right parietal stimulation. The results are discussed in the broad theoretical framework of the multicomponent model of working memory.     

The social mentality theory of self-compassion and self-reassurance: The interactive effect of care-seeking and caregiving

ABSTRACT

The aim of this study was to test social mentality theory, which views self-compassion/reassurance as a form of intrapersonal relating in which the interpersonal mentalities of care-seeking and caregiving are activated. Self-report measures of motivations, cognitions, and behaviors related to seeking and receiving care from others were administered to 195 students. Self-compassion/reassurance was predicted by the interaction of care-seeking and caregiving, with the positive effect of care-seeking intensified at high caregiving. As hypothesized, the combination of high care-seeking and high caregiving predicted the highest level of self-compassion/reassurance. The lowest level of self-compassion/reassurance was predicted by the combination of low care-seeking and high caregiving consistent with the concept of compulsive caregiving. Findings suggest that fostering a kinder way of relating to oneself may be achieved through more effective care-seeking and caregiving with others.     

Short theta burst stimulation to left frontal cortex prior to encoding enhances subsequent recognition memory

Deep semantic encoding of verbal stimuli can aid in later successful retrieval of those stimuli from long-term episodic memory. Evidence from numerous neuropsychological and neuroimaging experiments demonstrate regions in left prefrontal cortex, including left dorsolateral prefrontal cortex (DLPFC), are important for processes related to encoding. Here, we investigated the relationship between left DLPFC activity during encoding and successful subsequent memory with transcranial magnetic stimulation (TMS). In a pair of experiments using a 2-session within-subjects design, we stimulated either left DLPFC or a control region (Vertex) with a single 2-s train of short theta burst stimulation (sTBS) during a semantic encoding task and then gave participants a recognition memory test. We found that subsequent memory was enhanced on the day left DLPFC was stimulated, relative to the day Vertex was stimulated, and that DLPFC stimulation also increased participants’ confidence in their decisions during the recognition task. We also explored the time course of how long the effects of sTBS persisted. Our data suggest 2 s of sTBS to left DLPFC is capable of enhancing subsequent memory for items encoded up to 15 s following stimulation. Collectively, these data demonstrate sTBS is capable of enhancing long-term memory and provide evidence that TBS protocols are a potentially powerful tool for modulating cognitive function.     

Neurocognitive mechanisms behind emotional attention: Inverse effects of anodal tDCS over the left and right DLPFC on gaze disengagement from emotional faces

Background

Attention to relevant emotional information in the environment is an important process related to vulnerability and resilience for mood and anxiety disorders. In the present study, the effects of left and right dorsolateral prefrontal cortex (i.e., DLPFC) stimulation on attentional mechanisms of emotional processing were tested and contrasted.

Methods

A sample of 54 healthy participants received 20 min of active and sham anodal transcranial direct current stimulation (i.e., tDCS) either of the left (n = 27) or of the right DLPFC (n = 27) on two separate days. The anode electrode was placed over the left or the right DLPFC, the cathode over the corresponding contra lateral supraorbital area. After each neurostimulation session, participants completed an eye-tracking task assessing direct processes of attentional engagement towards and attentional disengagement away from emotional faces (happy, disgusted, and sad expressions).

Results

Compared to sham, active tDCS over the left DLPFC led to faster gaze disengagement, whereas active tDCS over the right DLPFC led to slower gaze disengagement from emotional faces. Between-group comparisons showed that such inverse change patterns were significantly different and generalized for all types of emotion.

Conclusions

Our findings support a lateralized role of left and right DLPFC activity in enhancing/worsening the top-down regulation of emotional attention processing. These results support the rationale of new therapies for affective disorders aimed to increase the activation of the left over the right DLPFC in combination with attentional control training, and identify specific target attention mechanisms to be trained.

     

Self-compassion and body-related self-conscious emotions: Examining within- and between-person variation among adolescent girls in sport

ObjectivesSelf-compassion protects against the occurrence of negative body image experiences and may be particularly useful in defending against negative body- and appearance-related self-conscious emotions in sport. The aim of this study was to examine within- and between-person associations between self-compassion and appearance-related self-conscious emotions.Design & MethodIn a three-year longitudinal cohort study, adolescent girls involved in organized sport (N = 518, M_age = 14.02 ± 1.38) completed yearly self-reports of self-compassion, body- and appearance-related shame, guilt, embarrassment, and envy.ResultsBased on findings from multilevel models, higher levels of both average and time-varying self-compassion were associated with lower levels of body-related shame, guilt, embarrassment, and envy. Specifically, girls reported lower levels of negatively valanced self-conscious emotions when self-compassion was higher than usual.ConclusionsThese findings support previous accounts on the utility of self-compassion as a buffer against negative body image experiences and extend these findings to appearance-related self-conscious emotions in the sport context. In light of the declining levels of self-compassion for girls in adolescence, it is important to focus intervention efforts on cultivating self-compassion to protect girls from negative body-related emotional experiences in sport.