Body ownership can be studied via the rubber hand illusion (RHI), in which an artificial limb can be perceived as belonging to oneself. In the so-called moving RHI paradigm, both body ownership and sense of agency, induced by self-produced movements, can be investigated. The key question of this approach is whether movements generated by oneself increase the illusion of body ownership. Thus far, the results from moving RHI studies are inconsistent.This has led to uncertainty regarding the influences of the motor control mechanism on body ownership. Therefore, this study will present the first meta-analysis on moving RHI to estimate the illusory effectiveness induced by self-produced movements. A total of 23 experimental comparisons with 821 subjects were included in the meta-analysis. The results showed that the overall illusory effect induced by self-produced movements was superior toits control (e.g., asynchronous active movements) (Hedge’s g = 1.38, p < 0.001). However, due to dissimilarity in results between the studies, the sample size in the meta-analysis may not represent the general population. The subgroup analysis showed that studies using physical hands, such as wooden hands, yielded the largest effect compared to studies using a virtual projected hand or a video recorded image of the participant’s own hands. It can be speculated whether a three-dimensional hand with “realness” has an illusory advantage compared to hands presented in virtual or video image settings. Future studies need to apply aunified framework, particularly in experimental setups and measurements. This would obtain consistent results of the strength of the illusion within the moving RHI paradigm.

Several trials have reported rapid antidepressant response from the anesthetic drug ketamine although the mechanism behind this effect is not fully understood. Research has focused mainly on ketamine’s action in the brain, including its effects on chemical balance, connections between brain cells and networks, and cognition. Trials with psychedelic drugs have had similar antidepressant results as ketamine, and the quality of the subjective psychedelic experience seems to mediate antidepressant action. Ketamine causes similar alterations of consciousness, which have been viewed as side effects. This thesis examines whether ketamine works in a similar way as psychedelics, where the ketamine-induced dissociative-like experience has a relationship to antidepressant response. Leading theories of depression and ketamine’s action in the brain are presented, and eight studies examining the relationship between ketamine-induced subjective experience and antidepressant response are reviewed. Three included studies found a relationship between psychedelic- and dissociative-like symptoms and reduction in depression, while five did not. The supposed relationship between psychedelic- and dissociative-like symptoms and antidepressant action has not been adequately explored and needs further examination in clinical trials.

Clustering of single-cell RNA sequencing data is often used to show what states and subtypes cells have. Using this technique, striatal cells were clustered into subtypes using different clustering algorithms. Previously known subtypes were confirmed and new subtypes were found. One of them is a third medium spiny neuron subtype. Using the observed heterogeneity, as a second task, this project questions whether or not differences in individual neurons have an impact on the network dynamics. By clustering spiking activity from a neural network model, inconclusive results were found. Both algorithms indicating low heterogeneity, but by altering the quantity of a subtype between a low and high number, and clustering the network activity in each case, results indicate that there is an increase in the heterogeneity. This project shows a list of potential striatal subtypes and gives reasons to keep giving attention to biologically observed heterogeneity.

Bakgrund Bäckenbottendysfunktion (BBD) är vanligt hos personer som genomgått förlossning, och kan påverka den hälsorelaterade livskvaliteten. Fysioterapeutisk behandling av BBD kan både symptomlindra och förbättra den hälsorelaterade livskvaliteten (HRQoL). Syfte Att beskriva hur personer 1-5 år postpartum skattar sina bäckenbottenbesvär och sin hälsorelaterade livskvalitet, samt att utreda sambandet mellan BBD och HRQoL. Att utreda hur många av deltagarna som fått behandling av fysioterapeut. Metod I tvärsnittsstudien deltog 205 personer med bäckenbottendysfunktion (medelålder 33,56 år, SD=±4,7). En webbenkät publicerades på fyra Facebooksidor. För korrelationerna användes icke-parametrisk statistik och beräknades med Spearmans korrelationskoefficient. Resultat Medianvärdet för deltagarnas skattade BBD med PFDI-20 var 95. Högst skattat av deltagarnas HRQoL mätt med RAND-36 var delskalan fysisk funktion med medianvärde 80, lägst var vitalitet med 35. Korrelationerna mellan BBD och olika delar av HRQoL varierade mellan delskalan smärta (r= -0,550) som högst, emotionell rollfunktion (r= -0,358) som lägst, och alla korrelationer hade p<0.001. Starkast negativ korrelation mellan sexuell dysfunktion och HRQoL hittades inom dimensionen fysisk funktion (r= -0,517), och svagast för vitalitet (r=-0,235). Samtliga korrelationer hade p<0,001. Av samtliga deltagare har 40% träffat fysioterapeut/sjukgymnast. Konklusion Deltagarna skattade sin BBD högre än en normalpopulation. Studien påvisar en negativ korrelation både mellan BBD mätt med PFDI-20, en egenformulerad fråga om sexuell dysfunktion och skattad HRQoL mätt med RAND-36. Trots upplevd BBD har enbart hälften av deltagarna fått vård för sina besvär. / Background Pelvic floor dysfunction (BBD) is common among people post partum, and it can affect the health-related quality of life (HRQoL). Physiotherapy for the pelvic floor can both ease symptoms and improve HRQoL. Purpose To describe how people 1-5 years postpartum estimate their BBD and their HRQoL, and to investigate the correlation between BBD and HRQoL. To investigate how many of the participants that have received treatment from a physiotherapist. Method In this cross-sectional study 205 people with BBD participated (mean age 33.56 years, SD=± 4.7). A web survey was published on four Facebook pages. Non-parametric statistics were used, and calculated with Spearman's correlation coefficient. Results The median value for the participants' estimated BBD with PFDI-20 was 95. The highest of the participants' HRQoL measured with RAND-36 was the subscale physical function with a median value of 80 and the lowest was vitality with 35. The correlations between BBD and the various subscales for HRQoL varied between pain (r = -0.550) as the highest, and emotional role function (r = -0.358) as the lowest, and all correlations had p <0.001. The strongest negative correlation between sexual dysfunction and HRQoL was physical function (r = -0.517), and the weakest was vitality (r = -0.235). All correlations had p <0.001. Of all participants, 40% have seen a physiotherapist. Conclusion The participants rated their BBD higher than an average population. The study shows a negative correlation between BBD measured with PFDI-20, a question about sexual dysfunction and estimated HRQoL measured with RAND-36. Despite perceived BBD, only half of the participants have received care for their problems.

The traditional diagnosis of patients with disorders of consciousness relies solely on behavioral responses. In 1996 it was estimated that 43% of patients diagnosed with unresponsive wakefulness syndrome (vegetative state) receive the wrong diagnosis. Assessing consciousness is perhaps the most crucial part of the diagnostic process. The challenging task of identifying covert consciousness in this patient group seems to be the biggest issue. In 2006 willful modulation of brain activity in response to a mental imagery task was discovered in a patient with unresponsive wakefulness syndrome. The brain activity was measured with functional magnetic resonance imaging. It was concluded that consciousness was preserved in this patient and new research investigating this novel method began to take place. The aim of this thesis was to conduct a systematic review of the literature and thereby arrive at the best current estimate of the proportion of patients who receive a diagnosis that wrongfully defines them as “unconscious” although they in fact are “covertly conscious”. In this review, 11 studies were examined. The results showed that patients with unresponsive wakefulness syndrome, who still receive the wrong diagnosis, decreased to 22-28% by the use of neuroimaging. This improvement points to the possible use of neuroimaging methods in the diagnosis of disorders of consciousness. However, this result cannot be taken without reservations. The limitations of the studies have to be taken into consideration. For example, most studies included a limited sample size and healthy controls did not always give the expected response to mental imagery tasks.

Adolescence is an exceptional period of life, not least in terms of social and brain development. Friends become increasingly important, susceptibility to peer rejection increases, and brain regions involved in social cognition are predicted to go through major changes. Adolescents’ social lives today may, to different extents, take place on social-media platforms online. This systematic review investigates how social-media use (SMU) affects adolescents’ brains. Out of 626 studies from the initial search, seven met the inclusion criteria. Out of these, five studies used functional magnetic resonance imaging, one study used diffusion tensor imaging, and one study used diffusion-weighted imaging. Functional findings suggest the reward circuit of the brain, as well as brain regions implicated in social cognition, to be involved in SMU. Activity in the nucleus accumbens was elicited by both giving and getting likes on posted pictures, whereas more SMU related to increased activity in the medial prefrontal cortex during physical self-judgement. Structural findings indicate frequent SMU to be associated with more reward sensitivity in terms of increased white matter in reward-processing pathways. These studies provide an initial understanding of the neural mechanisms of adolescents’ SMU. Future research is needed to draw inferences about how SMU affects the brains of adolescents.

Fluorodeoxyglucose Positron Emission Tomography (FDG PET) and Magnetic Resonance Imaging (MRI) are commonly used in a clinical setting as an examination in Alzheimer’s Disease (AD) patients. FDG PET is an imaging tool to evaluate hypometabolism; meanwhile, the MRI observes the brain volume. However, it is still unclear which examination better reflects the tau tangles, which have been known as the hallmark’s pathology of AD. Therefore, this study was conducted to compare FDG PET and MRI in assessing tau pathology in AD, by utilizing a database from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). The presence of tau tangles was confirmed by using the Tau-PET images. In total, 275 cognitively impaired subjects were included as well as a subgroup of 147 subjects with positive amyloid status. Based on the analysis, it was observed that higher Tau-PET is significantly associated with FDG PET hypometabolism and MRI atrophy. A similar result was also seen in the amyloid positive subgroups. By comparing the spearman’s correlation coefficients, it was found that that the correlation was stronger between Tau PET and FDG PET (r=-0.414, p<0.001, and r=-0.475, p<0.001 in the positive amyloid subgroup) compared to Tau-PET and MRI (r=-0.331, p<0.001 and r=-0.440, p<0.001 in the positive amyloid subgroup). Inconclusion, FDG PET better reflects the tau pathology compared to MRI in AD.

Emotions are a central part of our lives and the ability to effectively regulate them is central to well-being. Although a lot of research shows the beneficial role of sleep on emotional reactivity and regulation, little is known about how dream emotions relate to emotional reactivity and regulation. The current study investigated how dreams with high vs low levels of self-rated negative dream affect related to next-day waking emotional reactivity and regulation. Participants kept a home dream diary until reporting dreams on five days. They also reported dream and wake emotions and performed an online emotional reactivity and regulation task. Opposing predictions were derived from the continuity hypothesis and from the emotion regulation theories of dreaming. However, no significant differences were found between emotional reactivity and regulation on mornings following dreams with high vs low negative affect. Thus, no support was provided for the direct predictions made from the two theories. Nevertheless, morning wake affect differed significantly as a function of dream emotions. Specifically, participants reported significantly higher levels of positive emotions on mornings after a dream low, rather than high, in negative affect. Similarly, wake morning negative affect was higher following dreams high, rather than low, in negative affect. Thus, the results support a form of affective continuity between dreams and morning wakefulness.

An increasing amount of research suggests Ketamine in subanaesthetic doses to be an effective antidepressant for Major Depressive Disorder (MDD) and Treatment-Resistant Disorder (TRD). After the finding that NMDA-receptor antagonists may hold antidepressant effect, several studies have suggested Ketamine to have great effect in relief of depressive symptoms. A time lag between biological and behavioural effects have been shown in currently available antidepressants and are not guaranteed to be efficient; only 30% of patients reach adequate response. The aim for this thesis is to systematically review available studies on the efficiency of Ketamine's antidepressant effects in patients with TRD. Scopus, Web of Science, and PubMed were the databases searched for relevant research regarding the subject. Six articles were included in the analysis. A compilation of the results presented a moderate to large effect size for Ketamine compared to placebo at 24 hours through day seven. It is of immense weight that prolonged adverse effects and possible abuse are taken into consideration for future research, as well as how to sustain the dramatic acute antidepressant effect of Ketamine.

The late positive potential (LPP) is increasingly used as an indicator of emotional salience, which can be reduced by effective emotion regulation (ER), thus making LPP differences a practical marker of ER effects. One commonly used ER strategy is that of explicit distraction, a form of distraction that is consciously monitored and directed. Studies have shown that distraction modulates the LPP, and there are theoretical as well as empirical reasons to suspect that distraction occurs at an early stage in the timecourse of the LPP. However, the consistency of these findings have not yet been systematically assessed. This systematic review was conducted to address this gap in the literature. Following a literature search across three databases, nine empirical studies were systematically reviewed to assess the consistency of the effect of distraction on LPP latency and amplitudes. Mean LPP amplitude measurements from 270 healthy young adults, engaging in distraction and passive viewing during exposure to emotional stimuli, were gathered and reviewed. Mean differences were compared to assess the consistency of the LPP during distraction. Results showed consistent early LPP activation at centro-parietal sites, but not at frontal sites. These findings support the predictions of the process model of ER and its conceptualization of distraction as an antecedent strategy. The review was limited by the small number of studies, low mean ages of participants, and lack of diversity in stimuli, among other factors. As additional research is needed to further the scientific understanding of ER and its mechanisms, future directions are suggested.