Feelings of social connection are important to maintain physical and psychological well-being. Perceived social isolation, or loneliness, is the subjective experience of feeling socially isolated and may be a direct threat to our health. During recent years, an increasing amount of people report high levels of loneliness, potentially brought on by the COVID-19 pandemic and its restrictions. Recent research suggests that the brain’s default mode network (DMN), a neural network active at wakeful rest, is related to these experiences. This paper aimed to systematically review alterations in the DMN in socially connected and lonely individuals. I searched PubMed and Scopus to find studies using self-report measures of social connection or loneliness, and functional or structural neuroimaging methods on healthy adults. Nine studies were included in this review. Generally, core regions of the DMN typically involved in episodic memory and self-referential processing showed increased activity in lonely individuals and decreased activity in socially connected individuals. These findings may reflect how lonely individuals ruminate about past social events while socially connected individuals attend less to the self. However, methodological heterogeneity between studieslimits the conclusions that can be drawn based on these results.

Stress is a global health issue and effective stress management techniques are much needed. Mindfulness meditation in the form of mindfulness-based interventions have been shown to be effective interventions for self-reported stress reduction. However, the effects of mindfulness meditation on the objective physiological markers of stress are less clear. Heart rate variability, the variation in time between each consecutive heartbeat has been shown to be such an objective physiological marker of stress. The aim of this systematic review was to investigate how mindfulness-based interventions affect heart rate variability to better understand the utility of mindfulness meditation as a stress management technique. A literature search was conducted on March 8th, 2022, with the databases Web of Science, Scopus, and MEDLINE EBSCO to identify randomized controlled trials that examined the effects of mindfulness-based interventions on heart rate variability. A total of 10 studies met the inclusion criteria with a total of 970 participants. The results from the systematic review were mixed and indicate inconsistencies across the literature. Thus, there are uncertainties on how mindfulness-based interventions affect heart rate variability. Although the systematic review was limited by a small sample of studies, it highlights that further research on how mindfulness-based interventions affect heart rate variability is needed to better understand the utility of mindfulness meditation as a stress management technique.

Body Dysmorphic Disorder (BDD) is a mental disorder where the patient is preoccupied with a misperceived deficit in their appearance. It is a common disorder (~2% prevalence worldwide), leaving the patients significantly disabled and distressed. Comorbid disorders such as social phobia, depression, and anxiety disorders appear frequently. Previous neuroimaging studies have found heterogeneous abnormalities in brain regions involved in visual and emotional processing when comparing BDD patients to healthy controls. Some of these areas are involved in limbic structures. The emotional limbic system (involved in emotion recognition, reward, social behaviour, and decision-making) and the memory hippocampal limbic system (involved in episodic memory, information about objects, faces, and spatial locations) have been stated as two separate neural systems. The aim of this systematic review was to analyse the neural correlates of BDD focusing on structural changes in limbic structures, and further investigate whether the emotional limbic circuit exclusively is affected or solely higher influenced than the rest of the limbic structures. Abnormalities in information processing due to aberrant WM connectivity was found, as well as that volumetric alterations in GM and WM tracts correlate with clinical symptomatology. The relationship between visual and emotional processing system abnormalities and BDD severity suggests an involvement of the emotional limbic system in BDD.

The Wim Hof Method (WHM) is a contemporary combination of techniques including a breathing exercise, mindset and cold exposure. Interest in the method has blossomed in recent years as scientific studies has presented promising results on the methods impact on the autonomic nervous system (ANS) as well as the immune system. However, although biological factors have been demonstrated as a result of the method, psychological measures are lacking. In this study Subjective Well Being (SWB) was measured which refers to psychological attributes such as happiness, fulfilment and enrichment. As a biological marker Heart Rate Variability (HRV) was measured as it is theorised to be an indirect measure of the ANS which in turn often have been associated to reflect mental health. Measures of SWB and HRV were assessed pre- and post-intervention. Thirty-two participants met the inclusion criteria and were randomised into an intervention group and a control group. The intervention group was asked to do 10 days of WHM home practice after an initial introductory training. Meanwhile the control group were asked to live life as usual. Twenty-six participants completed the post assessments, and the collected data were analysed across time. It was found that participants in the intervention group reported a significant decrease in negative affect from pre-intervention to post-intervention in comparison to those in the control group. The present study adds to the existing research on the WHM by assessing new measures that reflect psychological well-being, namely SWB and HRV.

Patients with antisocial personality disorder (ASPD) are deceptive, apathetic, and impulsive. Their social behavior is often inappropriate, and they fail to follow social norms, leading to frequent criminal behavior. Understanding the neural correlates of ASPD could alleviate issues for the patients, such as unstable living conditions, as well as financial costs for the justice system and society. Due to previous research and theoretical implications of the prefrontal cortex (PFC) and its role in emotion-regulation and decision-making, it is likely that ASPD patients would show differences in the PFC relative to healthy individuals. Therefore, emphasis is placed on this region. By systematically reviewing articles which used fMRI to examine ASPD patients, this paper aims to understand if the brain activity in the PFC or functional connectivity within these regions differs between ASPD patients and healthy controls. Decreased activity was found in the anterior cingulate cortex (ACC) and dorsolateral PFC (dlPFC) in ASPD patients compared to healthy controls. Further, decreased functional connectivity was found in the frontoparietal control network, default modenetwork, and attentional network. Other prefrontal regions implicated include the medial frontal cortex, orbitofrontal cortex, and medial prefrontal cortex. Most of these regions are important for cognitive control, enabling integration of information regarding, e.g., errors and conflict. Abnormal processing of such information can lead to the impulsive or inappropriate actions often seen in ASPD patients. The PFC seems to play an important functional role in ASPD, mainly the regions responsible for cognitive control, such as the ACC and dlPFC.

Background: Ayahuasca is a South American psychoactive brew that contains Dimethyltryptamine (DMT) and monoamine oxidase inhibitors (MAOIs). Research has experienced a resurgence of interest in exploring the potential of these substances in the last decade. Thus, the aim of this review was to systematically review studies that used a placebo-controlled design to explore the neural correlates and psychedelic experience induced by DMT and ayahuasca. Method: The search was conducted using the Web of Science and Scopus databases to select studies published between January 2000 and February 2022 that used neuroimaging techniques and recruited healthy participants. Thus, 7 papers were selected. Results: Ayahuasca alters electrical activity in the brain by decreasing spectralpower in all EEG frequency bands, predominantly in the alpha band. DMT caused a spatially widespread decrease in alpha bands and a more modest decrease in beta bands. Ayahuasca caused an increase in the flow of information in the brain from posterior regions to more frontal regions and an increase in scores in all the Hallucinogen Rating Scale (HRS) subscales. Ayahuasca decreased connectivity in the Default Mode Network (DMN) and increases connectivity between DMN and the salience network. Conclusion: Ayahuasca and DMT can reliably produce profound changes in perception, emotions, and sense of self. Moreover, the decrease in the alpha band, the alteration of information flow between posterior and frontal regions, and the decrease in connectivity in the DMN could be the keystone understanding the neural correlates and the psychedelic experience induced by DMT andayahuasca.

Cognitive dissonance is the uncomfortable psychological feeling that arises when something is perceived as contradictory. In 1957, Leon Festinger first developed the theory of cognitive dissonance, which has since continued to be of interest for, among other things, decision-making, moral reasoning, motivation, politics, and science. This systematic review summarises six peer-reviewed studies that use functional magnetic resonance imaging (fMRI) to measure if there is increased activity in the anterior cingulate cortex (ACC) and dorsal anterior cingulate cortex (dACC) during cognitive dissonance in adults. Four studies tested cognitive dissonance during forced choices and two during counter-attitudinal behaviours. The overall fMRI results indicate increased activity in ACC and dACC to dissonance versus control conditions, but with some inconsistency on the exact locations in the brain.

Anorexia Nervosa (AN) is a severe and complex psychiatric disorder characterized by significantly low body weight, an intense fear of gaining weight, and a distorted body image. Despite otherwise successful treatments, body image distortions are often persistent and are considered a critical factor in the persistence, development, and relapse of AN. The present review outlines the current literature on tactile distance processing in AN to investigate and discuss its proposed role in the persistence and development of a distorted body image. The discussion of literature further discusses its implications for cognitive neuroscience since AN patients display similar symptoms as patients diagnosed with body image-related neuropsychiatric disorders with damage to the parietal lobe. The evidence suggests that individuals with AN have poorer tactile distance estimation than controls but do not differ regarding tactile detection. This review outlines the current literature, identifies gaps within the methodology, and proposes novel directions for future research.

The method targeted memory reactivation (TMR) uses specific stimulation when subjects are completing tasks and during sleep. The TMR process is known to influence the consolidation of declarative memories. The aim of this thesis is to conduct a systematic review on the effects of TMR on declarative memory consolidation during slow-wave sleep (SWS). The research question is to answer what effect TMR during SWS has on the consolidation of declarative memory in healthy humans when presented with associated cues of the targeted learning experiences. Eighteen studies were included in this review. Four studies found a significant effect of TMR on declarative memory consolidation, and 10 found a non-significant effect. In four studies the effect of TMR depended on different inclusions, analyses, and factors, for example between slow oscillation up-and down-states and between participants that vary in pre-sleep performance in the examined task. In contrast to previous findings, this review does not provide evidence for the effect of TMR on declarative memories during SWS. More research analysing different factors, such as different cues, age of participants, duration of SWS, and specific experimental tasks, needs to be done in the fields of TMR and auditory cues.

Developmental Dyslexia (DD), Attention Deficit Hyperactivity Disorder (ADHD), and Educational Attainment (EA) are highly prevalent conditions that have a significant impacton individuals' academic and social functioning. These conditions have a complex genetic basis and are often comorbid. To assess the polygenic architecture of these traits, psychiatric genetics researchers utilize a sophisticated tool known as polygenic scores (PGS). By combining numerous genes of individually modest effects, PGS summarizes an individual's genetic risk as a single score. In this study, we aimed to examine the association between PGS for ADHD and EA with typical DD traits. Using a meta-analytic approach, we analyzed data from earlier studies and found that PGS-ADHD accounts for 1.2% of the variance in DD, with a pooled effect size of r = -0.11 (95% CI = [-0.171, -0.050]). Similarly, PGS-EA accounted for 3.2% of the variance in DD, with a pooled effect size of r = 0.18 (95% CI = [0.070, 0.288]). Although these effect sizes are relatively small, it is important to note that PGS are not typically strong predictors on their own, but rather capture a small portion of the genetic variation that contributes to a trait or outcome. My findings suggest that PGS for ADHD and EA are associated with DD, indicating that DD has a complex genetic basis. However, these findings also raise questions about the impact of PGS on psychiatric research moving forward. To address these questions, I provide recommendations for future researchdirections.