Humans are social beings whose interaction with others constitutes an important part of our well-being. In these social interactions there are certain factors that are essential for us to feel comfortable. One of these factors is to keep a proper “breathing space”. A physical distance to whom we interact, to not have our personal space violated. This space we keep to others is called interpersonal distance (IPD) and might be altered depending on the situation. In the recent decade the neural correlates of IPD have been investigated. The current systematic review aimed to investigate the existing literature on the neural correlations of IPD and how it relates to IPD-behaviour. A systematic search was made in the electric databases Scopus and PubMed. Nine articles remained to be reviewed after screening and selection was done.The results showed the superior parietal cortex, the medial prefrontal cortex, motor areas, occipital areas, and the amygdala to be the most prominent structural brain areas to be involved in IPD. Some functional connections between mentioned brain areas were found but needs to be replicated for better knowledge. The review provides insight into the neural nature of IPD and its behavioural basis.

Gambling disorder is today a common disorder causing lives to shatter. As this disorder activates the reward system and increases the need of dopamine, recovering from gamling disorder can be hard. Research has shown that gambling addiction appears to have similarities to substance abuse, but no substance has been named. Therefore, this systematic review discusses similarities and differences between gambling and opioid addiction. The aim is to compare behavior and neurological correlates of gambling and opioid addiction tocreate a better understanding of the relationship between these addictions and hopefully help improve treatments. My expectation was that I would find behavioral and neurological similarities between opioid and gambling addicts. To investigate this, I conducted a systematic search across databases. I compared six studies which all used a task to investigate decision-making ability and brain-scanning to investigate neural correlates. Both gambling and opioid addicts show decreased activation in the orbitofrontal cortex, which plays a central role in decision-making. Regarding task performance, some studies showed addicts to perform worse than controls, suggesting that addicts show an impaired decision-making ability compared to controls. This systematic review contributes to the literature within addiction, but to draw a conclusion that gambling and opioid addicts suffer from similar decision-making impairment further research is needed.

Gender differences in emotion regulation (ER) are well documented, but studies have often relied on behavioral and self-report data. Less is known about gender differences in the neural basis of ER. This systematic review aims to fill this gap and investigate gender differences in the neural basis of ER. The systematic search process ended in eight articles, using either structural or functional neuroimaging methods while investigating the neural correlates of ER using either an ER task to manipulate ER or assessed trait ER with questionnaires. The studies either used reappraisal or expressive suppression as ER strategies. The results were partly inconsistent, but most studies demonstrate the involvement of areas within the prefrontal cortex in ER. Males activated areas involved in cognitive control while females activated emotion-focused areas involved in emotional processing. There is disagreements among researchers whether more activity in the prefrontal cortex represent more effort during ER (and how it does so), as well as whetherless activity represent less effort or more efficient regulation. These insights may help us understand each other better. Future research is needed to address if activation within the prefrontal cortex reflects more or less efficiency when regulating emotions.

Alzheimer's disease is the most common dementia disease and the main cause of death. The hallmark is neurofibrillary tangles (abnormal aggregates of tau protein) and beta-amyloid (Aβ) neuritic plaques that leads to impaired cognitive function such as memory loss and learning difficulties. Researchers have discovered that intermittent fasting improves these cognitive abilities, even though eating regularly is recommended for good cognition. This systematic review aims to investigate further if intermittent fasting improves cognitive function in Alzheimer’s disease and if levels of Aβ and tau pathology explain these changes in cognitive function. The research question is: does intermittent fasting improve cognitive abilities in Alzheimer’s disease and does the levels of Aβ and tau pathology explain these cognitive changes? A literature search for articles was performed on three electronic databases: Pubmed, Web of Science, and WorldCat which gave n=744 articles. The cognitive tests showed a trend toward improved memory, learning, and exploratory behavior in Alzheimer’s disease from intermittent fasting. However, the effects on the levels of Aβ and tau pathology were inconsistent, which invites the possibility of a more prominent, underlying issue of Alzheimer's disease.

The purpose of this systematic review was to characterize further the structural differences in the prefrontal cortex, limbic and paralimbic regions and amygdala alone in psychopaths. Psychopathy is a multifaceted personality disorder characterized by interpersonal and affective traits like lack of empathy, guilt or remorse, shallow affect, and carelessness, as well as behavioral traits such as impulsivity, and poor behavioral control. In recent years, the interest in the neuroanatomical differences in psychopaths has grown. This review aims to understand the prefrontal cortex, limbic and paralimbic areas, and how these regions differ between psychopathic patients and healthy controls. By systematically screening articles that used magnetic resonance imaging (MRI) and voxel based morphometry (VBM) the studies in this review examined people with psychopathic traits. To assess for psychopathy, the most used assessment tool, the Psychopathy Checklist-Revised (PCL-R) was used. Results show that the higher the PCL-R scores of the offenders, the less gray matter volume was found in the superior parts of the prefrontal cortex, limbic and paralimbic areas. Additionally, amygdala deficits in individuals with psychopathy were found. This systematic review may benefit in the way that if we increase our understanding of psychopathy and pave the way forthe creation of effective psychopathic treatments it could prevent future acts of violence. The link between a structural brain anomaly and psychopathy may have a profound clinical, legal, and scientific impact. A psychopathy diagnosis may serve as a precursor to severe societal violence.

The aim of this systematic review is to present the current literature on the therapeutic potential of the classic psychedelic compound psilocybin for depressive disorders and the neurocognitive mechanisms involved recorded with functional magnetic resonance imaging (fMRI). A comprehensive literature search was conducted in the electronic databases Web of Science, Scopus and Medline EBSCO using a Boolean search string containing the keywords psilocybin, depression, fMRI, MRI and PET. Our inclusion criteria require original neuroimaging research articles published in scientific peer-reviewed journals involving participants diagnosed with depression receiving psilocybin in conjunction with psychological support. Five articles were identified including a total of 104 participants with depression and 75 who received treatment, resulting in significant reduction of depressive symptoms associated with observable changes in neural activity. Specifically reduced cerebral blood flow (CBF) in amygdala, decreased brain modularity along with functional changes in default mode network (DMN), executive network (EN), salience network (SN), decrease in functional connectivity (FC) between ventromedial prefrontal cortex (vmPFC) to amygdala and increased amygdala reactivity to fearful faces. Limitations of our systematic review include a currently limited amount of articles published and thus lack of control groups in most studies. The current evidence indicates that the therapeutic potential of psilocybin-assisted therapy may provide fast acting and efficient amelioration of depressive symptoms and the effects may be mediated by neurocognitive changes acute and post-treatment. The preliminary results warrants further research in order to optimize treatment and establish safety and efficacy long term.

Some unanswered questions about consciousness as a biological phenomenon lie in its evolutionary origin and distribution among living organisms. Which animals are conscious and when did consciousness appear in the history of life on earth? The purpose of this thesis is to shed light on these long-standing questions by reviewing the literature on the evolutionary approaches to the fundamental concept of phenomenal consciousness. In agreement with the “Cambridge Declaration on Consciousness,” this study aims to introduce three recently developed theories, with a particular emphasis on examining one model. The “Cellular Basis of Consciousness” (CBC) is a reductionist, cellular-based model that argues all organisms from unicellular to humans are sentient. Another theory based on neuroevolutionary arguments is called the “Neurobiological Naturalism.” It suggests that consciousness first appeared duringthe Cambrian period about 550 million years ago. This model considers vertebrates, arthropods and cephalopods as conscious animals. An alternative framework, which is the main focus of this thesis, is the “Unlimited Associative Learning” (UAL). The UAL model employs a novel method to formulate a transition marker as an indicator of consciousness. Although the UAL framework is a promising method for tracing the evolution of consciousness, it also has significant limitations. Nevertheless, the literature review reveals that as an innovative framework, UAL has the potential to generate fruitful research programs. Rather than providing a final answer, it can be considered a significant starting point for unraveling the origin of consciousness.

Blindsight is a phenomenon in which patients suffering damage to the primary visual cortex (V1) perceive themselves as blind, but nonetheless seem to have some residual capacity to distinguish between visual stimuli better than chance. Blindsight can be divided into two subtypes: blindsight type I and blindsight type II. Blindsight type I is defined as visual capacity in the absence of acknowledged awareness. Patients with blindsight type II have visual capacity with some feeling or sensation in the blind field. Visual pathways bypassing V1 are assumed to be responsible for the residual capacity in blindsight. To investigate whether these pathways are present in healthy individuals we examined if it is possible to induce blindsight in healthy individuals by reviewing studies that have tried to induce blindsight with transcranial magnetic stimulation (TMS). We found that TMS might be able to induce blindsight type I of side detection. We also found that TMS might be able to induce blindsight type II of colour, orientation, and trustworthiness. Further, we found that both conscious and unconscious perception of shapes are dependent on processing in early visual cortex (EVC) in healthy individuals. We conclude that the full capacity seen in blindsight is most probable caused by neural reorganisation post trauma. The visual pathways bypassing V1 are, if present in healthy individuals, too weak to influence behaviour with the possible exception of side detection. Additionally, we conclude that the use of a binary awareness scale in blindsight studies fails to capture vaguely seen stimuli.

A current controversy in the science of visual consciousness is whether conscious awareness of a stimulus emerges gradually or appears directly in an all-or-none fashion. Windey et al. (2013) observed that evidence supporting the gradual explanation often used low-level stimuli (simple shapes, colours), while evidence for a dichotomous divide of awareness used high-level stimuli (letters, numbers). Windey later constructed the level of processing (LoP) hypothesis, which states that different stimulus levels impact the transition to awareness, i.e. whether it occurs gradually or in an all-or-none fashion. Koivisto et al. (2017) further showed, using high-level stimulus, that different conceptualizations of awareness (detection and identification) impact different electrophysiological correlates of awareness. Specifically, the visual awareness negativity (VAN) only occurred for awareness based on detection, while the late positivity (LP) occurred for both detection and identification. The purpose of this thesis is to further investigate the VAN and LP for detection and identification, but with a low-level stimulus. Following the level of processing hypothesis, I expect that the mean amplitudes will be more negative in the VAN time range and more positive in the LP time range for identification trials compared to detection trials. Similarly, I expect VAN and LP to occur for both detection and identification. Unfortunately, the current results did not find any significant differences due to the low sample size. However, the results for the identification threshold hint towards a VAN but no LP.

Nature and greenspaces have been enjoyed throughout history and used for relaxation purposes. Several theories, such as biophilia and stress recovery theory, suggest nature’s ability to improve stress recovery. Even though stress helps detect danger and enhances alertness, it causes fatigue and distortive cognitive functions if prolonged. Nature-based intervention such as Shinrin-yoku or forest bathing, which refers to relaxing walks in forest environments, has been recently researched and used to reduce stress in individuals. The current study is an experimental study aimed at whether attendance in nature is beneficial for stress recovery. Ten subjects were divided into an experimental group (walks in nature) and a control group (walks in a city environment). They were tested for stress levels using heart rate variability (HRV) and the Karolinska exhaustion disorder scale (KEDS) before and after the walks. The result demonstrated no significant differences in stress recovery for both measurements before and after walks in nature compared to walks in a city environment. Despite that, it did not reject nature’s positive impact on stress recovery. Therefore more research on nature-based intervention and stress recovery is required.