This thesis investigates the relationship between structural and functional aspects of the visual cortex by modelling parts of the outer structures of the brain. In particular, it studies the dynamics of the brain during bistable perception. This is a phenomenon in which an observer changes the interpretation of what he perceives without the visual object changing. This thesis investigates the mechanism underlying this phenomenon. The models in this thesis are based on the biological structure of the brain. By finding the same behaviour in the model as in the perceptual experiment, we can directly see which biological components are responsible for bistable perception. Subsequent experiments can further test the hypotheses arising from this thesis. For example, by using fMRI to focus on these structures in the cortex.

Bistable perception involves the spontaneous alternation between two exclusive interpretations of a single stimulus. Previous research has suggested that this perceptual phenomenon results from winnerless dynamics in the cortex. Indeed, winnerless dynamics can explain many key behavioral characteristics of bistable perception. However, it fails to explain an increase in alternation rate that is typically observed in response to increased stimulus drive and instead predicts a decline in alternation rate. To reconcile this discrepancy, several lines of work have augmented winnerless dynamics with additional processes such as global gain control, input suppression, and release mechanisms. These offer potential explanations at an algorithmic level. But it remains unclear which, if any, of these mechanisms are implemented in the cortex and what their biological substrates might be. We suggest that the answers to these questions may lie within the laminar architecture of the cortical microcircuit. Utilizing a dynamic mean field approach, we implement a laminar columnar circuit with empirically derived interlaminar connectivity. By coupling two such circuits such that they exhibit competition, we are able to produce winnerless dynamics reflective of bistable perception. Within our model, we show that two mechanisms emerge from the layered structure that ensure increased alternation rate in response to increased stimulus drive. First, deep layers act to inhibit the upper layers, thereby reducing the attractor depth and increasing the alternation rate. Second, recurrent connections between superficial and granular layers implement an input suppression mechanism which again reduces the attractor depth of the winnerless competition. These findings suggest the functional significance of the layered cortical architecture as they showcase perceptual implications of neuroanatomical properties such as interlaminar connectivity and layer-specific activation.

Background: Current literature mainly focuses on adaptive profiles from a categorical perspective but yields inconclusive results. The present study puts a transdiagnostic approach next to a "classical" categorical approach.Methods: In this study, 222 children (5-18 years old) with autism and/or intellectual disability participated. Variance analyses, based on standard scores from ABAS-3 at group-level, were conducted in order to compare adaptive domains within categories. A K-Means cluster analysis was used to delineate empirically derived clusters with a similar profile of difference scores at an individual level. Chi-square tests and variance analyses were used to investigate the distribution of variables across clusters.Results: From a categorical perspective, results were in line with current literature. A transdiagnostic perspective revealed three adaptive profiles (Homogeneous, Social, and Practical). No perfect match was found between specific adaptive profiles and diagnostic categories.Conclusions: A transdiagnostic perspective sheds light on the heterogeneity within and the overlap across diagnostic categories.

Stressful life experiences may jeopardize the healthy development of children. To improve interventions, more knowledge is needed on the perception of stress by children. In adults, stress is regarded as a state of low valence and high arousal. It is unclear whether children perceive stress similarly. In the current study, 35 children of the general population completed three tasks aiming to provide insight into their knowledge of the concept stress. In the first task, participants were asked about their verbal knowledge of the con-cept stress. In the second task, they rated the valence and arousal of eight emotion-evoking vignettes. In the final task, participants completed an experience sampling survey for at least 1 day, con-sisting of a stress thermometer and pictorial scales of valence and arousal. Participants' perception of stress was found to be mainly valence focused. Age and sex were found to play a role in the degree of arousal focus. Older participants differentiated more in arousal levels than younger participants, as did girls in compar-ison with boys. Because the perception of stress depends on devel-opmental and other individual factors, using stress as a single measurement dimension in a survey is not recommended.(c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Using a mixed methods design, this study aimed to examine the impact of the COVID-19 pandemic on autistic and non-autistic adults. We conducted an online survey with 196 autistic and 228 non-autistic adults from Belgium, the Netherlands and the United Kingdom focusing on their experiences during the first period of the pandemic. Our results indicate rather diverse experiences within the group of autistic participants across all domains of life. In comparison with non-autistic adults, autistic adults reported less negative impact on their social life and more negative impact on health and support services. In the autism group, stress was mainly related to changing and unclear measures. A wide range of coping strategies were described as helpful in reducing stress during the pandemic.

Autistic individuals are at particular risk of experiencing mental health problems during the COVID-19 pandemic, yet little is known about personal characteristics that may underlie this vulnerability. This longitudinal questionnaire study with 149 autistic and 147 non-autistic adults investigated the association between perceived stress and anxiety and depressive symptoms, measured 4 months later. In addition, the moderating impact of intolerance of uncertainty and coping styles on this association was examined. Confirming previous studies, autistic adults reported poorer mental health than non-autistic individuals. Results demonstrated similar moderation models across individuals with versus without autism. Perceived stress at timepoint 1 was associated with anxiety and depression at timepoint 2. Across both participant groups, individuals with maladaptive coping strategies and higher levels of intolerance of uncertainty at timepoint 1 showed more internalizing symptoms at timepoint 2. The findings demonstrate the burden of the pandemic on the mental health of autistic adults, especially on those with high levels of perceived stress, maladaptive coping strategies, or intolerance of uncertainty. Interventions to support autistic adults during and after the pandemic might involve providing psychoeducation about the impact of stress, coping, and intolerance of uncertainty on internalizing symptoms, and teaching more adaptive ways to cope with difficult circumstances. Lay abstract More and more research shows us that autistic individuals are at risk of experiencing mental health problems in response to the COVID-19 pandemic. However, little is known about why this is the case. At two timepoints during the pandemic, we asked 149 autistic and 147 non-autistic adults about feelings of anxiety, depression, and stress, and about characteristics that may explain why some (autistic) people have a larger chance of developing anxiety and depression during this pandemic. In our study, autistic adults experienced more anxiety and depression than non-autistic adults. Across autistic and non-autistic individuals, the people who experienced more stress at timepoint 1 experienced more anxiety and depression 4 months later. This was especially the case for those individuals who use maladaptive coping styles, such as denial or venting, and for those who have difficulties dealing with uncertain situations. Our findings show the burden of the COVID-19 pandemic on the mental health of autistic adults. Interventions to support autistic adults during and after the pandemic are needed, and they may want to focus on the negative impact of stress and teach autistic (and non-autistic) adults more adaptive ways to cope with stressful circumstances.

The present study examines to what extent two core characteristics of the quality of life (QoL) construct were incorporated in the field of autism: (1) its subjective nature; and (2) its multidimensionality. Therefore, we reviewed 174 articles examining QoL in individuals with autism. The review showed parents reporting a lower QoL compared with autistic individuals themselves, especially on internal domains. This may suggest different expectations about what a good QoL may entail. Such an underestimation of QoL by others is commonly observed in individuals with disabilities (the so-called 'disability paradox'). For the multidimensionality of the QoL construct, our findings suggest that the narrower (and more unidimensional) construct of health-related QoL is often measured instead of QoL. Additionally, a substantial proportion of items did not measure QoL, but they evaluated characteristics that may or may not have an impact on QoL. Researchers and clinicians should be aware that QoL domains are selected and operationalized differently by different instruments. QoL may benefit from an exclusive focus on subjective aspects, which can be measured alongside more normative, objective characteristics of individuals or their environment.

Background The goal of this systematic review was to provide an overview of self-report measures of stress in populations on the autism spectrum. In addition, information regarding psychometric properties was discussed as well. Methods Four databases were systematically searched following the PRISMA guidelines and using strict eligibility criteria. Risk of bias assessment was performed using the COSMIN checklist. Results Eight questionnaires were previously used in populations on the autism spectrum, reported over 31 studies. Discussion Future research should focus more on examining psychometric properties of these self-report measures in this population as current evidence is scarce. In addition, it is important to consider which concept of stress one aims to measure as not all questionnaires cover the same aspects of stress.

Stimulus-induced oscillations and synchrony among neuronal populations in visual cortex are well-established phenomena. Their functional role in cognition are, however, not well-understood. Recent studies have suggested that neural synchrony may underlie perceptual grouping as stimulus-frequency relationships and stimulus-dependent lateral connectivity profiles can determine the success or failure of synchronization among neuronal groups encoding different stimulus elements. We suggest that the same mechanism accounts for collinear facilitation and suppression effects where the detectability of a target Gabor stimulus is improved or diminished by the presence of collinear flanking Gabor stimuli. We propose a model of oscillators which represent three neuronal populations in visual cortex with distinct receptive fields reflecting the target and two flankers, respectively, and whose connectivity is determined by the collinearity of the presented Gabor stimuli. Our model simulations confirm that neuronal synchrony can indeed explain known collinear facilitation and suppression effects for attended and unattended stimuli.

Two semi-structured parental interviews are available with algorithms developed to measure DSM-5 criteria of ASD, namely the Developmental, Dimensional and Diagnostic Interview (3di) and the Diagnostic Interview for Social and Communication Disorders (DISCO-11). The main aim of this study was to examine the agreement between classification according to both interviews, and their convergence with the clinical diagnosis. Therefore, the 3di and DISCO-11 were administered from three groups of parents of a 4-18 year old. Results showed 75% agreement between both instruments, but in the ASD group only 16% of the children scored above threshold on both instruments. Exploratory analyses suggested that the 3di failed to detect rigid and repetitive behaviors, whereas the DISCO-11 was insufficiently sensitive in detecting socio-communicative problems.

Here, we explored the structure of the 'Parenting Strategies Questionnaire', a new scale designed to measure parenting strategies for problem behaviour in ASD. We then examined links between child behaviour and parenting in a sample of 222 predominantly-UK parents of ASD children exhibiting behaviour found difficult or challenging. Analysis revealed three parenting subscales: Accommodation, Reinforcement Approaches and Reducing Uncertainty. Both Accommodation and Reducing Uncertainty were linked to child problem behaviour. Child factors explained up to 29% of the variance in Accommodation, with Socially Inflexible Non-compliance the strongest predictor, and up to 24% of the variance in Reducing Uncertainty, with Intolerance of Uncertainty the strongest predictor. Child factors were not related to Reinforcement Approaches. Longitudinal studies investigating these relationships are needed.

Visual perception in individuals with autism spectrum disorder (ASD) is often debated in terms of enhanced local and impaired global perception. Deficits in global motion perception seem to support this characterization, although the evidence is inconsistent. We conducted a large meta-analysis on global motion, combining 48 articles on biological and coherent motion. Results provide evidence for a small global motion processing deficit in individuals with ASD compared to controls in both biological and coherent motion. This deficit appears to be present independent of the paradigm, task, dependent variable, age or IQ of the groups. Results indicate that individuals with ASD are less sensitive to these types of global motion, although the difference in neural mechanisms underlying this behavioral difference remains unclear.

The target article by Borsboom et al. proposes network models as an alternative to reductionist approaches in the analysis of mental disorders, using mood disorders such as depression and anxiety as examples. We ask how this framework can be applied to neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Specifically, we raise a number of promises and challenges when conceptualizing neurodevelopmental disorders as networks.

Developmental research on Gestalt laws has previously revealed that, even as young as infancy, we are bound to group visual elements into unitary structures in accordance with a variety of organizational principles. Here, we focus on the developmental trajectory of both connection‐based and object‐based grouping, and investigate their impact on object formation in participants, aged 9–21 years old (N = 113), using a multiple‐object tracking paradigm. Results reveal a main effect of both age and grouping type, indicating that 9‐ to 21‐year‐olds are sensitive to both connection‐based and object‐based grouping interference, and tracking ability increases with age. In addition to its importance for typical development, these results provide an informative baseline to understand clinical aberrations in this regard. Statement of contribution What is already known on this subject? The origin of the Gestalt principles is still an ongoing debate: Are they innate, learned over time, or both? Developmental research has revealed how each Gestalt principle has its own trajectory and unique relationship to visual experience. Both connectedness and object‐based grouping play an important role in object formation during childhood. What does this study add? The study identifies how sensitivity to connectedness and object‐based grouping evolves in individuals, aged 9–21 years old. Using multiple‐object tracking, results reveal that the ability to track multiple objects increases with age. These results provide an informative baseline to understand clinical aberrations in different types of grouping.

Although there is increasing research interest in the parenting of children with ASD, at present, little is known about everyday strategies used to manage problem behaviour. We conducted a meta-synthesis to explore what strategies parents use to manage irritability, non-compliance, challenging behaviour and anxiety in their children with ASD. Approaches included: (1) accommodating the child; (2) modifying the environment; (3) providing structure, routine and occupation; (4) supervision and monitoring; (5) managing non-compliance with everyday tasks; (6) responding to problem behaviour; (7) managing distress; (8) maintaining safety and (9) analysing and planning. Results suggest complex parenting demands in children with ASD and problem behaviour. Findings will inform the development of a new measure to quantify parenting strategies relevant to ASD.

Although research shows that young adults with autism spectrum disorder (ASD) struggle with higher rates of depression, anxiety, and other co-occurring psychiatric disorders, their psychological development through emerging adulthood remains understudied. To explore relevant developmental themes for young adults with ASD while subscribing to a social-constructionist epistemology, we interviewed young adults with ASD and their mental health care professionals individually, and organized focus groups with their parents in a multiperspective design. Developmental themes were identified using interpretative phenomenological analysis. Despite a substantial body of research considering lack of social motivation, a central ASD characteristic, narratives were remarkably socially oriented. This article discusses the overarching themes of (a) searching for balance and negotiating ASD and (b) searching for suitable surroundings in different areas of life, as well as their implications for clinical practice.

Developmental research on Gestalt laws has previously revealed that, even as young as infancy, we are bound to group visual elements into unitary structures in accordance with a variety of organizational principles. Here, we focus on the developmental trajectory of both connection-based and object-based grouping, and investigate their impact on object formation in participants, aged 9–21 years old ( N  = 113), using a multiple-object tracking paradigm. Results reveal a main effect of both age and grouping type, indicating that 9- to 21-year-olds are sensitive to both connection-based and object-based grouping interference, and tracking ability increases with age. In addition to its importance for typical development, these results provide an informative baseline to understand clinical aberrations in this regard. What is already known on this subject? What does this study add?

Autism spectrum disorder (ASD) is typically associated with problems in social communication and interaction, combined with restrictive and repetitive interests, behaviors, and activities. In addition, individuals with ASD often experience sensory abnormalities and have difficulties with perceptual organization, which can affect other aspects of information processing, such as attention, and perception of faces and motion. Researchers have studied atypical perceptual organization in individuals with ASD over the past decades, particularly in visual perception, finding both a reduced tendency to integrate information into meaningful wholes and a stronger focus on details in individuals with autism. In this article, we review empirical findings and describe briefly two influential theoretical accounts (weak central coherence and enhanced perceptual functioning theory), as well as more recent theoretical frameworks that emphasize the imbalance between local and global processing, or anomalies at the level of the brain as an engine of prediction.