A system for the visual detection and analysis of obsessive compulsive disorder

Computer vision is a burgeoning field that lends itself to a diverse range of challenging problems. Recent advances in computing power and algorithmic sophistication have prompted a renaissance in the literature of this field, as previously computationally expensive applications have come to the fore. As a result, researchers have begun applying computer vision techniques especially prominently to the analysis of human actions, in an increasingly advanced manner. Chief among the potential applications of such human action analyses are: human surveillance, crowd analysis, gait analysis and health informatics. Even more recently, researchers have begun to realise the potential of computer vision techniques, occasionally in conjunction with other computational approaches, to enhance the quality of life for people living with mental illness. Much of this research has focused on enhancing the existing, traditionally psychiatric, treatment plans for such individuals. Conventionally, these treatment plans have involved a mental health professional taking a face-to-face approach and relying significantly on subjective feedback from the individual, regarding their current condition and progress. However, recent computational methods have focused on augmenting such approaches with objective, e.g. visual, monitoring and feedback on an individual's condition over time. Of these approaches, most have focused on depression, bipolar disorder, dementia, or some form of anxiety. However, none of the approaches described in the literature has been aimed directly at addressing the issues inherent to patients with Obsessive Compulsive Disorder. Motivated by this, the proposed thesis comprises the design and implementation of a system that is capable of detecting and analysing the compulsive behaviours exhibited by individuals with Obsessive Compulsive Disorder. This is accomplished with the aim of assisting mental health professionals in their treatment of such patients. We achieved the aforementioned via a three-pronged approach, which is represented by the three core chapters of this thesis. Firstly, we created a system for the detection of general repetitive (compulsive) behaviours indicative of Obsessive Compulsive Disorder. This was achieved via the use of a combination of optical flow detection and thresholding, an image matching algorithm, and a set of repetition parameters. Via this approach, we achieved good results across a set of three tested videos. Secondly, we proposed a system capable of classifying behaviour as either compulsive or non-compulsive based on the differences in the repetition intensity patterns across a set of behavioural examples. We achieved this via a form of motion history image, which we call a 'Temporal Motion Heat Map' (TMHM). We produced one such heat map per behavioural example and then reduced its dimensionality using histogram-based pixel intensity frequencies, before feeding the result into a Neural Network. This approach achieved a high classification accuracy on the set of 40 tested behavioural examples, thus demonstrating its ability to accurately differentiate between compulsive and non-compulsive behaviours, as compared to a set of existing approaches. Finally, we built a system that is capable of categorising different types of behaviour, both compulsive and non-compulsive, and then assessing them for relative approximate anxiety levels over time. We achieve this using a combination of Speeded-Up Robust Features (SURF) descriptors for behaviour classification and statistical measures for determining the relative anxiety of a given compulsion. This system is also able to achieve a good accuracy when compared with other approaches

Functional organisation of behavioural inhibitory control mechanisms in cortico-basal ganglia circuitry: implications for stimulant use disorder.

The neural and psychological mechanisms of inhibitory control processes were investigated, focusing on the cortico-basal ganglia circuits in rats and humans. These included behavioural flexibility, ‘waiting’ and ‘stopping’ impulsivity and involved serial spatial reversal learning task in rodents, and in humans, premature responses in the Monetary Incentive Delay (MID) task and the stop-signal reaction time task. Chapter 2 and Chapter 3 focus on individual differences in behavioural flexibility in rats while Chapter 4, Chapter 5 and Chapter 6 consider how inhibitory control mechanisms are affected by the psychostimulant drug cocaine in both rats and humans. As reported in Chapter 2, systemic modulation of monoaminergic transmission by monoamine oxidase A (MAO-A) inhibitors enhanced reversal learning performance, selectively by decreasing the lose-shift probability, thereby implicating a role for dopamine, serotonin and noradrenaline in facilitating learning from negative feedback. Resting state functional magnetic resonance imaging (fMRI) revealed enhanced functional connectivity of the orbitofrontal and motor cortices as a correlate of flexible reversal learning performance, consistent with elevated levels of monoamines in these region (Chapter 3). Having clarified the mechanisms underlying behavioural flexibility in rats, Chapter 4 reports that escalation of intravenous cocaine self-administration induces behavioural inflexibility in rats even after a relatively short period of cocaine intake. Computational models, including a reinforced and Bayesian learner, revealed a lack of exploitation of the learned response-outcome relationships in cocaine-exposed rats. Chapter 5 focused on impulse control in human volunteers, identifying the striatal and cingulo-opercular networks as substrates of impulsive, premature responding in healthy 4 volunteers, stimulant-dependent individuals and their unaffected siblings. Loss of impulse control was elicited by different incentives for drug-free participants as opposed to drug users. Drug cues elicited striatal activation and increased premature responses in the stimulant-dependent group compared with the control group. In contrast, the ventral striatum was linked to incentive specific activation to reward anticipation. Task-based fMRI demonstrated that interactions between dorsal striatum and cingulo-opercular “cold cognition” networks underlie failures of impulse control in the control, at-risk and stimulant-dependent groups. However, whereas the cingulo-opercular networks were associated with premature responding in all groups, the reward system was activated specifically by the drug incentive cues in the stimulant group, and by monetary incentive cues in the drug-free groups. Chapter 6 presents evidence that corticostriatal functional and effective connectivity in an overlapping network that includes the anterior cingulate and inferior frontal cortices as well as motor cortex, the subthalamic nucleus and dorsal striatum, is critical to stopping impulse control in both control and cocaine individuals. No stopping efficiency impairments were observed in the cocaine-dependent group. Nevertheless, lower structural corticostriatal connectivity measured using diffusion MRI was associated with response execution impairments in cocaine participants performing a stop-signal reaction time task. Further, response execution was rescued by the selective noradrenaline reuptake inhibitor atomoxetine, which also increased corticostriatal effective connectivity. Finally, increased impulsivity and behavioural inflexibility seen in stimulant use disorder in Chapter 5 and Chapter 4, respectively, were not observed in the endophenotype at risk for developing stimulant abuse but were rather a consequence of stimulant abuse. These results further clarify the monoaminergic substrates of behavioural flexibility and specify the neural and computational impairments in inhibitory control induced by stimulant dependence.Pinsent Darwin Studentship from the Dept of Physiology, Development and Neuroscienc

A phenomenological investigation of the role of guilt in obsessive-compulsive disorder

The current study takes a phenomenological approach to investigating the role of guilt in a sample of persons diagnosed with Obsessive-Compulsive Disorder (OCD). The role of guilt in OCD has been frequently noted in the literature, although infrequently studied as a significant factor in its own right. Typically, those studying OCD have found positive correlations between questionnaire measures of guilt and self-reported symptoms of the disorder. Those working with sufferers have also found that OC clients in therapy report feelings of guilt with respect to their symptoms, although the particular phenomenology of the relationship between guilt and symptoms is not especially clear in the clinical literature. The present work investigates in a qualitative way, the meaning of guilt for those with OCD. The presumed role of guilt in OCD is examined in a descriptive fashion, with an eye to developing a fuller, more complete understanding of the relationship between feelings of guilt and OC symptoms in a sample of sufferers. Nine participants (N=9) were recruited, and were interviewed using an unstructured approach. In terms of analysis, emphasis was placed on understanding the experience of guilt and OC symptoms as both were lived by sufferers, with a focus on the personal significance of guilt for study participants. Fifteen descriptive guilt/OCD themes were derived from interviews across the nine participants. Themes revealed the variety of connections that subjects made between feelings of guilt and symptoms of OCD. As well, the specific patterns of themes within the context of individual participants' lives were also described. The results suggest that the role of guilt in OCD is highly interpersonal in nature, and that feelings of guilt may precede and motivate, as well as follow and be a consequence of, the expression of OC symptoms. The particular role of guilt for any given sufferer may also be highly idiosyncratic. Research and clinical contributions, as well as limitations of the research, are discussed

Exploring model-based and model-free reinforcement learning in obsessive-compulsive disorder

RESUMO: A Perturbação Obsessivo-Compulsiva (POC) é uma doença neuropsiquiátrica comum, grave e incapacitante, para a qual os tratamentos actuais são ineficazes num grande número de casos. O instrumento mais utilizado para avaliar a gravidade de sintomas obsessivo-compulsivos é a Yale-Brown Obsessive-Compulsive Scale (YBOCS), que foi recentemente revista (Y-BOCS-II). No entanto, a sua validade de construto (tanto divergente como convergente) tem sido reportada como moderada e a sua validade de critério para diagnóstico de POC nunca foi testada. No primeiro capítulo desta tese testei, pela primeira vez, a validade de critério da Y-BOCS-II e demonstrei que um ponto de corte de 13 (pontuação total) atinge o melhor balanço entre sensibilidade e especificidade para o diagnóstico de POC. No entanto, confirmei que a sua validade divergente está longe de ser excelente. Este último achado levoume a procurar outros potenciais marcadores de POC. Têm sido demonstradas várias anomalias em doentes com POC utilizando tarefas neuropsicológicas ou técnicas de neuroimagem. Contudo, não existe ainda um marcador consistente para esta perturbação, que seja capaz de discriminar eficazmente pacientes que sofrem de POC, que seja sensível à mudança após intervenções terapêuticas e para o qual seja possível estabelecer uma correspondência com circuitos ou função cerebral. Uma abordagem que tem sido seguida nos últimos anos considera a POC como sendo caracterizada por uma disfunção nos sistemas cerebrais responsáveis pela aprendizagem de acções. As tarefas de decisão sequencial emergiram recentemente como um instrumento importante e sofisticado para estudar a aprendizagem de acções em humanos através da abordagem de reinforcement learning (RL). De acordo com a teoria subjacente ao RL, as acções podem ser aprendidas de duas formas distintas: um sistema modelbased funciona através da construção de um modelo interno das dinâmicas do ambiente e utiliza esse modelo para planear trajectórias comportamentais futuras, por oposição a um sistema model-free, que funciona armazenando o valor estimado das acções que foram implementadas recentemente e actualizando essas estimativas por tentativa e erro. As chamadas tarefas de decisão sequencial têm vindo a ser utilizadas para estabelecer associações entre disfunção de sistemas cerebrais de RL e algumas perturbações neuropsiquiátricas, como a POC, sendo que um desequilíbrio entre os sistemas model-based e model-free tem sido descrito. Através da aplicação de uma dessas tarefas de decisão sequencial, a two-step task, existe evidência que sugere que os doentes com POC têm um défice no sistema model-based. No entanto, neste paradigma em particular, antes de desempenhar esta tarefa os indivíduos recebem informação detalhada sobre a estrutura da mesma. Assim, não é claro como os dois principais sistemas de RL interagem quando os indivíduos aprendem exclusivamente através de interacção com o ambiente e como a informação explícita afecta as estratégias de RL. No segundo capítulo desta tese, desenvolvi uma nova tarefa de decisões sequenciais que permite não só quantificar o uso de estratégias modelbased RL e model-free RL, mas também diferenciar entre o impacto do conhecimento explícito da estrutura da tarefa e o impacto da experiência na mesma. Os resultados da aplicação da tarefa em indivíduos saudáveis demonstram que inicialmente a escolha de acções é controlada por aprendizagem model-free, com a aprendizagem model-based emergindo apenas numa minoria de indivíduos depois de experiência significativa com a tarefa, não emergindo de todo em indivíduos com POC, que por sua vez mostraram tendência para aumentar o uso de model-free RL com a experiência. Quando foi dada informação explícita sobre a estrutura da tarefa, observou-se um aumento dramático do uso de aprendizagem model-based, tanto nos voluntários saudáveis como em ambos os grupos clínicos. A informação explícita diminuiu o uso do sistema de aprendizagem model-free nos voluntários saudáveis e nos pacientes com perturbação do humor e ansiedade, mas essa diminuição não foi estatisticamente significativa no grupo de doentes com POC. Para além disso, depois das instruções, verificou-se em todos os grupos que a actualização do valor das acções aprendidas através do sistema model-free passou a ser mais influenciada pelo valor dos estados atingidos e menos influenciada pela consequência dos ensaios. Outro efeito da informação explícita sobre a estrutura da tarefa nos indivíduos saudáveis foi tornar as escolhas mais perseverantes, o que é consistente com uma modificação da estratégia de exploração. Estes resultados ajudam a clarificar o perfil de utilização de estratégias de RL dos pacientes com POC, que apresentam défice inespecíficos de aprendizagem model-based e achados mais específicos de maior uso de aprendizagem model-free, em ambos os casos antes de obterem informação sobrea estrutura da tarefa. Por fim, como a literatura ainda não é consensual sobre a interação entre um eventual sistema de model-based RL e um sistema de model-free RL nos circuitos cerebrais em humanos, devenvolvi um protocolo de ressonância magnética funcional para avaliar a escolha de ação sequencial com e sem instruções. Os resultados preliminares, em indivíduos saudáveis, sugerem que a reduced two-step task permite separar comportamento que utiliza aprendizagem predominantemente model-free (antes das instruções) de comportamento que utiliza aprendizagem predominantemente model-based (após as instruções), no mesmo indivíduo, estrutura da tarefa e ambiente. A análise dos dados de imagem funcional sugere que o conhecimento explícito sobre a estrutura da tarefa modifica a atividade neuronal no córtex paracingulado (cortex prefrontal medial) durante a transição do primeiro para o segundo passo da tarefa. Objectivos futuros incluem o uso de técnicas de análise multivariada para explorar a representação cerebral dos estados da tarefa e a aplicação deste protocolo de ressonância magnética funcional em populações clínicas.ABSTRACT: Obsessive-compulsive disorder (OCD) is a common, chronic and disabling neuropsychiatric condition for which current treatments are ineffective in a large proportion of cases. The gold-standard instrument to assess the severity of OCD symptoms is the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), which was recently revised (Y-BOCS-II). However, its construct validity has been reported has moderate and its criterion-related validity for the diagnosis of OCD has never been tested. In the first chapter of this dissertation, I tested, for the first time, criterion-related validity of the Y-BOCS-II and demonstrated that a cut-off of 13 (total score) attains the best balance between sensitivity and specificity for the diagnosis of OCD. However, I confirmed that its divergent validity is far from excellent. This last finding led me to search for other potential markers of OCD. Several abnormalities have been demonstrated in OCD patients in studies using neuropsychological and neuroimaging approaches, but we still lack a consistent marker for the disorder which is able to discriminate patients with OCD from healthy subjects or from patients with other mental disorders, which is sensitive to treatmentinduced changes, and which can be mapped to brain circuits or function. An approach which has been followed over the last decade is considering OCD as a disorder of action learning systems of the brain. Sequential decision tasks have recently emerged as an influential and sophisticated tool to investigate action learning in humans through the reinforcement learning (RL) framework. According to the RL framework, actions can be learned in two different ways: model-based control works by learning a model of the dynamics of the environment and later using that model to plan future behavioral trajectories, while model-free control works by storing the estimated value of recently taken actions and updating these estimates by trial-and-error. Sequential decision tasks have been used to assess associations between dysfunction in RL control systems and certain behavioral disorders, such as OCD, where an unbalance between model-based and model-free RL has been hypothesized. In fact, using the most commonly applied sequential decision task, the two-step task, evidence has been produced suggesting that OCD patients have a deficit in model-based learning. However, in this specific paradigm, subjects typically receive detailed information about task structure prior to performing the task. Thus, it remains unclear how different RL systems contribute when subjects learn exclusively from experience, and how explicit information about task structure modifies RL strategy. To address these questions, I created a sequential decision task requiring minimal prior instruction, the reduced two-step task. I assessed performance both prior to and after delivering explicit information on task structure, in healthy volunteers, patients with OCD and patients with other mood and anxiety disorders. Initially model-free control dominated, with model-based control emerging only in a minority of subjects after significant task experience, and not at all in patients with OCD, who had instead a tendency to increase their use of model-free control. Once explicit information about task structure was provided, a dramatic increase in the use of model-based RL was observed,similarly across healthy volunteers and both patient groups, including OCD. The debriefing also significantly decreased the use of model-free RL in healthy volunteers and in patients with mood and anxiety disorders, but not in OCD patients. Additionally, after instructions, model-free action value updates were influenced more by state values and less by trial outcomes, in all groups, and subject choices became more perseverative in healthy subjects, consistent with changes in exploration strategy. These results help in clarifying the RL profile for patients with OCD, with unspecific findings of deficient model-based control, and more specific findings of enhanced model-free control, in both cases prior to information about task structure. Finally, as the literature is not yet consensual on how model-free and modelbased RL systems interact in human brain circuits, I developed a functional magnetic resonance imaging (fMRI) protocol to assess uninstructed and instructed sequential action choice. Preliminary results in healthy subjects suggest that the fMRI version of the reduced two-step task allows to separate predominantly model-free control (before instructions) from predominantly model-based control (after instructions), in the same subject, task structure and environment. Across all sessions, choice events were associated with increases blood-oxygen-level-dependent (BOLD) activity in the left precentral gyrus and reward events were associated with increased BOLD activity in the ventral striatum. I found that explicit knowledge about task structure modifies blood-oxygen-level-dependent (BOLD) activity in the paracingulate cortex (medial prefrontal cortex) during the transition from the first- to the second-step of the task. Future directions include using multivariate pattern analysis techniques to explore how the brain represents state space in sequential decision tasks and applying the current fMRI protocol in clinical populations

Neuropsychological deficits in pediatric neurological disorders

D.Phil. (Psychology)Please refer to full text to view abstrac

Learning to regulate homeostatic brain networks

Eine dynamische Balance der physiologischen Gegebenheiten wie Körpertemperatur, Blutdruck, Blut-PH-Wert, Hormonspiegel, Blutzucker und Insulinkonzentration ist für die Gesundheit und das Überleben unverzichtbar. Viele Krankheiten haben eine Störung der Homöostase zur Folge. Vor allem das Nerven- und das Hormonsystem steuern Regulationsmechanismen und sobald diese ein Ungleichgewicht feststellen, gibt es passende biochemische oder physiologische Feedback-Kreisläufe, die den Gesamtzustand in die Balance zurückführen. Diese Dissertation untersucht neuartige Methoden des Echtzeit-Neurofeedbacks, das auf funktioneller Magnetre-sonanztomographie basiert (Real-time functional magnetic resonance imaging – rt-fMRI-NF), um es gesunden Probanden und Patienten zu ermöglichen, homöostatische Netzwerke des Gehirns zu regulieren. Die erste Studie hatte zum Ziel, die Auswirkungen der Hochregulierung der funktionellen Konnektivität durch rt-fMRI-NF-Training (engl. Functional connectivity – FC) zwischen Beloh-nungs- und impulsivitätsregulierenden Gehirnarealen auf das Essverhalten zu untersuchen. Diese Studie war ein Pilotexperiment im Pre-Post-Schema. Die zweite Studie untersuchte die Möglichkeit, die funktionelle Konnektivität zwischen der anterioren Insula (AIC) und dem soma-tosensorischen Kortex (SC) durch Belohnung von gleichzeitiger Aktivität dieser Regionen zu be-einflussen. AIC und SC sind Gehirnregionen, die physiologische Zustandsinformationen von Kör-pergewebe und großflächigen Hautsegmenten erhalten. Wir nahmen an, dass die funktionelle Verbindung zwischen diesen Regionen die Verarbeitung dieser Signale der inneren Organe und Körpergewebe übernimmt. Dies stellt einen Kernbereich des Gefühlskonzeptes von James-Lang dar. In der dritten Studie untersuchten wir, ob Patienten mit kontaminationsbezogenen Zwangsgedanken und Waschzwang lernen können, ihre BOLD-Aktivität in der Insula herunterzu-regulieren, wenn sie mit ekelerregenden oder Angst hervorrufenden Stimuli konfrontiert wer-den. Die Ergebnisse der ersten Studie zeigten, dass die willentliche Hochregulierung der Korrela-tion zu einer erhöhten funktionellen Konnektivität zwischen dem dorsolateralen präfrontalen Kortex (dlPFC) und dem ventromedialen präfrontalen Kortex (vmPFC) führt. Diese Konnektivität betrifft Selbstkontrolle und die Entscheidung für gesunde Nahrungsmittel. Die Verhaltenstests deuten darauf hin, dass die Probanden sich in der Transfersitzung (nach der Intervention) für weniger ungesunde Nahrungsmittel entscheiden als in der Sitzung vor der Intervention. Die zweite Studie bestätigte unsere Hypothese, dass die willentliche Hochregulierung von gleichzei-tiger BOLD-Aktivität von AIC und SC deren funktionale Konnektivität erhöht. Diese Verbindung ermöglicht eine verstärkte Körperwahrnehmung und ein verändertes subjektives Gefühlserle-ben. Wir beobachteten, dass die Veränderung der funktionellen Konnektivität zwischen AIC und SC die Leistung der Probanden in der Aufgabe (Wahrnehmung des Herzschlags) verbesserte. In der dritten Studie fanden wir heraus, dass Patienten mit Zwangsstörungen (OCD) nach einigen Trainingseinheiten die Selbstkontrolle der BOLD-Aktivität der Insula erreichen konnten. Fasst man die Ergebnisse der drei Studien zusammen, konnten wir zeigen, dass die Fähigkeit des Ge-hirns zur homöostatischen Selbstregulierung durch die Verwendung von rt-FMRI-Training ver-bessert werden kann. Zudem ist nun klarer, dass die Veränderung und die Modulation von neu-ronalen Pfaden in Gehirnnetzwerken, die der Selbstkontrolle, der Entscheidungsfindung und der Gefühlswahrnehmung zugrunde liegen, zu vielversprechenden Verhaltensveränderungen führt

OCD as a Dynamical Disease and the Familial Context of Ritual Rigidity: A Nonlinear Dynamics Perspective

Comparatively few studies of obsessive compulsive disorder (OCD) have addressed the interpersonal dynamical patterns within families that could exacerbate or quell symptom severity in the ill relatives or hypothesize other roles for familial variables. Furthermore, the extant studies have relied primarily upon linear models. Methodological limitations of linear models, such as assuming that change occurs as the result of unidirectional influences and that the scores obtained for each variable are independent of each other are at variance with temporal, dynamic phenomena and have restricted the empirical investigations of the dynamics of OCD. The current study investigated whether OCD could be considered a dynamical disease such that the complex rhythmic processes that are the norm for living things would be replaced by relatively constant dynamics or by periodic dynamics. Determining whether OCD could be a dynamical disease could improve our current treatment strategies or lead to the development of new treatment strategies, by finding ways to best control or alter the dynamics of the family system and determining when the best time for change could take place. To accomplish this, this study analyzed both the occurrence of rituals as they transpired over time and the influence the family may have had upon the spatiotemporal structure of symptoms. This information was obtained by using the time-diary method and comparing the time-series of 17 clinical cases with 16 matched controls. Comparisons of nonlinear regression parameters and Lyapunov exponents revealed that OCD exhibited a low-dimensional deterministic structure. The average nonlinear model (R2 = 0.32) explained more than 10 times the variance of its linear counterpart (R2 = 0.03). Family reactions and emotional responses accounted for only a very modest increase in the variance explained by the nonlinear regression model or in the amount of turbulence. Family reactions and emotional responses do little to make the rituals go away, but instead may strengthen the dynamics. Finally, significant rank order correlations were found between the R2 for each logbook and Lyapunov exponents with symptom severity and family reactions. Theoretical and practical implications of the results are discussed, including implications for treatment

How do therapists understand and use humour in their work with obsessive-compulsive clients? A grounded theory study

This qualitative research study seeks to explore how experienced therapists - the majority of whom are Cognitive Behavioural Therapists - understand humour; and how they use it in the treatment of Obsessive-Compulsive Disorder (OCD). Between two and three per cent of the population have OCD and the World Health Organization ranks it in the top ten most disabling illnesses. However, forty per cent of obsessive-compulsive clients who engage in Cognitive Behavioural Therapy (CBT) for OCD either refuse, do not finish or fail to benefit from treatment. At the same time, research indicates that the therapeutic alliance is the primary driver for client change in therapy; and that humorous interventions help to strengthen this alliance. Data from semi-structured interviews with eight participants were analysed using Willig’s abbreviated grounded theory method (2013) and a tentative model was constructed. Humour is presented as an expression of paradox in OCD (it being at once illogical, distressing and dangerous; as well as creative, informative and absurd). Participants continuously assess the type and function of humour used in session. ‘Light’ and soothing humour promotes constructive outcomes (distancing while closely bonded, playfulness, normalising, reframing); while ‘dark’ and provocative humour risks negative results (defending, offending, rupturing). When making decisions about humour use, participants have regard to both in-the-moment, and longer term, feedback on the strength of the therapeutic relationship; as well as certain individual differences (religion, class, gender, age, etc. of the client) and intrapsychic variables (the participant’s own experience, training and professional reputation). The implications for theory and practice are discussed, with an emphasis on enhancing knowledge in the field of counselling psychology. Recommendations for future research are also made

The flexibly ordered brain

I investigate the human brain systems involved in the cognitive control of behaviour. Using novel cognitive paradigms and brain imaging, I identify brain systems that support the flexible structuring of behaviour. I then observe how these systems are implicated in patients with depression as they respond to psilocybin therapy. In the first of three experiments, I observe the changes in healthy adult brain activation that are associated with task-switching. This demonstrated that remapping rules introduces a switching-cost to response speed and activates the multiple-demand (MD) network. Critically, switching-costs and MD activation were greater when the rules being remapped were of an abstract and higher-order nature. Going deeper, in the second experiment, I investigate how healthy adult brains mitigate switching-costs by structuring behaviour into efficient routines. I observe that learning to optimise and structure behaviour covaries with changes in MD and default mode network (DMN) activation alongside increases in between-network connectivity. These concurrent behavioural and neural adaptations imply that cognitive demand is minimised when behavioural routines are structured. Indeed, these mechanisms are known to have broad roles in flexibly adapting behaviour and, subsequently, they have been implicated in disorders such as depression. Using these insights, in the third experiment, I examine the neural basis of the treatment response to psilocybin in patients with depression. In two clinical trials, I find that treatment response covaried with global increases in between-network connectivity. Converging functional cartography measures indicated that this global shift in network organisation related to increased dynamic flexibility and integration of the MD and DMN. Together, the findings in this thesis indicate that a ‘flexibly ordered brain’, the adaptive sequencing of neurocognitive states, is a necessary feature of well-being and for successfully navigating the demands of daily life.Open Acces

Personality profiles of dysthymic disorder.

A Dissertation submitted to the Faculty of Medicine in part fulfilment of the requirements for the Degree of Master of Medicine in Psychiatry at the University of the Witwatersrand.The motivation for undertaking this study stems from the confusion that reigns in the literature regarding the relationship between personality, personality traits and dysthymic disorder. A large body of theorists ancl researchers still claim a definite association between dysthymia and personality. Their views arose to an extent from the concept of dysthymia as it developed through the past few decades. Dysthymia grew out of the concept of depressive neurosis which had a stronger basis in personality pathology. other terms like neurotic depression and depressive reaction preceded depressive neurosis. with the advent of DSM-III and DSM-III-R, dysthymia was moved from the neuroses to the mood disorders category. The DSM-IV Mood Disorders Work Group has also reinforced the classification of dysthymia with mood disorders. The Work Group has embarked on research to determine the symptomatology that should be used for the diagnosis of dysthymia. It is proposed that cognitive, functional and vegetative symptoms be included in DSM-IV to further entrench dysthymia as an affective disorder and extricate it from the personality disorders.Andrew Chakane 201