The rubber hand illusion is an experimental paradigm that induces the illusion of ownership over a fake hand. The illusion was originally induced using visuotactile stimulation but can also be induced using movements. Self-produced movements are active movements, and if they are produced by external force, they are passive movements. According to the comparator model, only active movements produce a sense of agency. As both passive and active movements can be used to induce the sense of ownership in the rubber hand illusion, but only active induce a sense of agency, they can be compared to determine the effect agency has on bodily ownership. This meta-analysis included nine studies with a total of 359 participants that compared the induced sense of ownership using active and passive movements in the rubber hand illusion to determine these effects. The results show that agency has a small but significant effect on body ownership.

Generalized anxiety disorder (GAD) is a prevalent anxiety disorder that is characterized by persistent excessive worrying that is often difficult to control. The pathology of GAD has been associated with abnormal neural activity and functional connectivity. This systematic review has examined the central neural correlates of GAD which are the prefrontal cortex (PFC), the anterior cingulate cortex (ACC) and the amygdala and how activation and functional connectivity in these brain areas differ between patients with GAD and healthy controls. This review also investigated how abnormal functional connectivity and activation in these brain regions relates to worry which is the most prominent psychological symptom in patients with GAD. A systematic review was conducted and seven original functional magnetic resonance imaging (fMRI) studies were included after a literature search on PubMed, Scopus and, Web of Science. The main findings from this review revealed decreased activation in the PFC and ACC and enhanced activation in the amygdala during the viewing of negative stimuli in patients with GAD. Identifying the neural correlates of GAD and how it relates to worry may provide improved treatment in the future such as developing more effective psychotropic drugs or improved psychotherapy. GAD has been associated with lower well-being and life satisfaction and may even be a risk factor for suicidal thoughts. One of the limitations from this review is that several of the included studies recruited patients with comorbidities and for that reason results from these studies cannot be generalized and applied to individuals with GAD.

The phenomenon of somatosensory attenuation describes the perception that self-generated touch feels weaker than externally generated touch of identical intensity. Previous studies have shown that besides intensity, self-generated touches feel less pleasant and less ticklish than identical externally generated touches. However, previous studies did not systematically assess attenuation across a range of stimuli that can elicit intensity, pleasantness, and ticklishness more efficiently. This thesis aims to replicate these previous observations across a range of tactile stimuli of different intensities and velocities and investigate whether people who attenuate their self-generated touches to a greater extent do so for all aforementioned qualities. Previous studies have shown that participants with lower levels of somatosensory attenuation have more schizotypal personality traits. Twelve volunteers participated in three perceptual tasks where they received touches on their sole generated either by a robot(External) or the participants(Self). Following the strokes, participants had to rate the sensation from 0(not at all) to 100(extremely). For the intensity task, we manipulated the intensity of the applied forces (1,2,3,4N). For the pleasantness and ticklishness tasks, we manipulated the velocity of the applied strokes (0.3,1,10,30cm/s). After the tasks, participants completed a Schizotypal Personality Questionnaire (SPQ). Significant somatosensory attenuation was observed in all tasks, but for specific, not all, stimuli: forces of 4N in terms of intensity, strokes of 1cm/s in terms of pleasantness, and strokes of 10cm/s and 30cm/s in terms of ticklishness. These results suggest that the ability to suppress the tactile consequences of self-generated touch occurs in all three tactile qualities.

Time-restricted eating is a fasting diet where the food intake is restricted to a short, typically eight-hour, window each day. It is associated with health benefits such as weight loss, improved sleep, protection against cognitive disorders, and improved cognitive function. The cognitive effects of time-restricted eating have primarily been explained by the production of ketogenesis – an alternative energy source produced when calories are restricted – and anti-inflammatory cytokines. The gut microbiota is the trillions of microorganisms inhabiting the intestinal tract and has also been associated with improved mental health through communication via the gut-brain axis. This review aims to investigate whether changes in the microbiota may mediate the effect of time-restricted eating on cognitive function. Studies investigating the effect of time-restricted eating on the microbiota were systematically reviewed. The results indicate that time-restricted eating may alter the microbiome composition and increase butyrate-producing bacteria. Butyrate is a short-chain fatty acid associated with the expression of genes involved in neural development and the reduction of neuroinflammation. Limited by the few studies reviewed, the results may indicate a possible link between time-restricted eating and cognitive function via the microbiota, although more research is needed.

This literature review examines the default mode network (DMN) and how its role in self related processing and narrative selfhood relates to well-being. The essay explores the DMN in three levels of activity: Firstly in normal function, where mind-wandering is positively correlated with dissatisfaction; Secondly its abnormal function in depression, characterized by excessive activity and rumination; Thirdly in its arguably improved function during mindfulness and meditation, where lower activity is associated with higher well-being, decreased mind-wandering and altered sense of self. The essay shows a relationship between the DMN and well-being, where higher activity correlates with lower well-being.

This thesis reviews the literature on theoretical cognitive neuroscientific findings linked to self-compassion, emotion regulation and compassion. Further, an empirical study was conducted with the aim to investigate correlational findings of self-compassion in relation to mental health in India. Mental health was measured through positive and negative affect, symptoms of generalized anxiety disorder and depression. The background of the thesis is mainly centred on the emotion regulation strategy cognitive reappraisal and compassion to provide more understanding of the links regarding self-compassion and mental health. The neural underpinnings regarding reappraisal and self-compassion are mostly related to dorsolateral prefrontal cortex, ventral striatum, anterior cingulate cortex, ventromedial prefrontal cortex, orbitofrontal cortex, insula and amygdala. These regions are involved in functions such as attention, memory, reward, emotion processes and responses. The correlational study involved 91 south Indian university students between the age of 19-24 years. The most significant results indicate a strong negative relationship between self-compassion and negative affect. Self-compassion was moderately positively correlated with positive affect. Furthermore, self-compassion was moderately negatively correlated with symptoms of depression. In addition, a strong positive correlation between negative affect and symptoms of depression was found. A discussion regarding current findings in relation to the neural underpinnings of emotion regulation and self-compassion, limitations of the study as well as directions for future research is provided.

This thesis aims to investigate and present what the most recent research can disclose about moral emotions and their neural correlates. This literature review provides an overview of some frameworks and theories regarding moral emotions and their neural correlates, with a specific focus on positive and negative moral emotions such as compassion, pride, gratitude, guilt, shame, and embarrassment. The theoretical background of moral emotions within cognitive neuroscience has been introduced together with research of the emotional brain and morality to further clarify the main topic of this thesis, moral emotions and their neural correlates. Moral emotions are very crucial in understanding humans’ behavioural adherence to their moral standards. For example, shame is described as the way we relate and perceive ourselves. It is related to how we believe and think other people see us and our incompetence or failure to fulfil the desire to be a good person, e.g. “I think, feel and believe that I am a bad person for lying to someone”. These topics have been discoursed through this thesis showing significant results. There are many neural regions, e.g. medial prefrontal cortex (mPFC) and posterior superior temporal sulcus (pSTS) which get activated whilst experiencing distinct moral emotions. However, studies have shown that there is no one-to-one correspondence between a specific brain area and a specific emotion, instead, research has suggested there are particular topographical anatomical networks in the brain which get activated when experiencing different emotions. There are few studies in this field; their results should be taken with caution. The field continues to grow, and we can learn more about moral emotions and their neural correlates today and in the future.

Major depressive disorder (MDD) is rapidly growing and one of the most common causes of disability and mortality worldwide. People with MDD often display brain changes such as adisrupted balance in neurotransmitters, impaired neurogenesis and neuroplasticity. Traditionally has MDD been treated with medications and talking therapies (psychotherapy). Studies have shown that just around 50 % of people with MDD get improvements from common traditional treatments.Therefore is there a great need for a better understanding of MDD and new treatments. There is now an emerging field of research that indicates that the gut microbiota plays a crucial role in disturbing normal brain functioning in MDD. This connection between the gut and the brain is called the gutbrain axis.The thesis aims to investigate if there is a connection between gut microbiota disruption and MDD and if gut microbiota restoration can be a potential effective future treatment for MDD. Key findings of the thesis were, studies show that people with MDD often display gut microbiota disruption and chronic low grade inflammation. Studies also indicate that this inflammation can cause the specific brain change often displayed in people with MDD. One of the most critical findings in the thesis was that gut brain treatments affect tryptophan metabolism, which affects the risk of MDD. The research area of the gut brain axis is still new and many more studies are needed,particularly in humans.

When the brain is exposed to a traumatic injury, the brain produces high amounts of neurosteroids like allopregnanolone and progesterone which show protective and neurogenic capacities. Alzheimer’s disease patients also have lower amounts of these neurosteroids in brain tissue. Neurosteroids act on GABAA receptors and cholesterol receptors which is interesting since both the cholesterol transporter ApoE and excitotoxicity seems to be issues plaguing the patients. To study if there is a relationship between Alzheimer’s disease and neurosteroids, there are ongoing phase one studies but neurobiological studies are equally important in order to understand the mechanism. In this work protective capabilities of allopregnanolone on induced toxicity was investigated in human neuroblastoma SH-SY5Y cells. Protection and induced toxicity were assessed by studying cell viability with MTT assay. Toxins used were the oxidative stress inducing agent t-BHP, excitotoxic glutamate and amyloid β25-35. Previous studies have found allopregnanolone to induce neurogenesis, decrease ROS levels, inhibit apoptosis and to have immunoregulatory capabilities. The present study did see an increase in cell viability when treated to 1x10-8 M allopregnanolone but this effect was not observed when the concentration was increased further to 1x10-7 M and 1x10-6 M. When the SH-SY5Y cells were treated with toxins after pretreatment of allopregnanolone, additional decrease was seen when compared to cells only treated with toxins. The present study discovered the influence of components like cell density and cell generation which is of value for researchers planning future neurobiological studies. These neurobiological studies give insight of the correct mechanisms in the brain, opening up opportunities for new efficient drugs to be developed.

Mindfulness practice is used to treat mental and physical symptoms. The problem is that research on the long-term effects and the neural changes involved, correlated with well-being, are inconsistent. The purpose of this review is to create a deeper understanding of mindfulness and its neural correlates related to stress. In mindfulness, one can use focused attention meditation (FA), involving anterior cingulate cortex (ACC), prefrontal cortex (PFC), parietal areas, thalamus, visual cortex, intraparietal sulcus, and amygdala. In open monitoring meditation (OM), ACC, PFC, insula, somatosensory cortex, limbic areas and amygdala are involved. In exposure to a high amount of stress, the grey matter volume decreases in the hippocampus, PFC, and amygdala. Research has also shown that 19 000 hours of mindfulness practice increases activation in areas involved in FA and OM. This increased activation might also enhance the subject’s ability to control emotions. After 44 000 hours of meditation, areas involved in FA showed less activation which might imply that more hours of mindfulness practice involve less cognitive activity and a calmer state of mind. Regardless of hours spent on meditating, a decreased activation in the amygdala and ACC occurs, which correlates with less response towards negative stimuli. The neural changes involved in mindfulness practice was related to less experienced stress and enhanced psychological well-being. For future research, an investigation of the interaction between attentional networks and stress would be of relevance.