35 research outputs found

    Fictional Practices of Spirituality I: Interactive Media

    Get PDF
    "Fictional Practices of Spirituality" provides critical insight into the implementation of belief, mysticism, religion, and spirituality into worlds of fiction, be it interactive or non-interactive. This first volume focuses on interactive, virtual worlds - may that be the digital realms of video games and VR applications or the imaginary spaces of life action role-playing and soul-searching practices. It features analyses of spirituality as gameplay facilitator, sacred spaces and architecture in video game geography, religion in video games and spiritual acts and their dramaturgic function in video games, tabletop, or LARP, among other topics. The contributors offer a first-time ever comprehensive overview of play-rites as spiritual incentives and playful spirituality in various medial incarnations

    Détection automatique multi-échelle et de grande envergure d'oscillations intracérébrales pathologiques dans l'épilepsie par réseaux de neurones artificiels

    Get PDF
    Environ un tiers des patients épileptiques sont résistants aux médicaments. La seule solution pour les guérir est de retirer la zone cérébrale à l'origine des crises, appelée zone épileptogène (ZE). Pour localiser cette zone, il est parfois nécessaire des mener des explorations par stéréo-électroencéphalographie (SEEG). L'analyse du signal EEG par les neurologues est une étape déterminante du diagnostic, mais la quantité de données générée est colossale. Ainsi, seule une petite partie des enregistrements peut être analysée par les équipes médicales qui se concentrent principalement sur l'activité durant les crises et celle juste autour. Pour caractériser l'étendue et la dynamique du réseau épileptogène, les neurologues étudient aussi des marqueurs intercritiques. Mais certains de ces biomarqueurs sont strictement invisibles à l'œil nu. Le premier objectif de ce travail de thèse interdisciplinaire consistait à établir de nouvelles méthodes pour détecter efficacement et automatiquement les marqueurs intercritiques, à savoir les pointes épileptiques intercritiques (PEIs) et en particulier les fast ripples (FRs). Le second objectif visait à définir et décrire l'intérêt d'enregistrements des marqueurs physiopathologiques de l'épilepsie par l'intermédiaire de micro-électrodes, alors que la plupart des études jusqu'à présent utilisaient des macro-électrodes classiques. Enfin, le troisième objectif était focalisé sur les FRs, avec pour idée de mieux comprendre leur origine, leur émergence et leur implication dans la pathologie. Nos équipes utilisent des électrodes hybrides permettant un enregistrement multi échelle du signal cérébral des patients. Ces électrodes sont constituées de macro-canaux permettant d'enregistrer l'activité de larges populations neuronales et de micro-canaux capables de capturer des signaux plus focaux, pouvant aller jusqu'à l'échelle du neurone unitaire. Nous avons construit un détecteur automatique de PEIs basé sur une nouvelle méthode de traitement du signal que nous avons baptisée Convolutional Kernel Density Estimation (CKDE). Nous avons également élaboré un détecteur automatique de FRs basé sur une approche écologique en trois étapes, imitant le travail du neurologue. Tous ces outils ont été incorporés à des interfaces graphiques utilisateurs (GUI) combinant les différentes fonctionnalités pour en permettre l'utilisation facile et efficiente. La détection des PEIs par CKDE offre la preuve de concept qu'une analyse orientée pixels de l'activité EEG peut être utilisée comme stratégie pour détecter des marqueurs intercritiques. Nous avons évalué cette méthode sur 10 minutes d'enregistrements chez un patient. Quinze PEIs ont été détectées automatiquement parmi lesquelles 13 vrais positifs et 2 faux positifs. Nos résultats principaux concernent toutefois la détection des FRs qui auraient à ce jour le plus grand potentiel dans le diagnostic des épilepsies pharmacorésistantes. Pour entraîner le CNN qui est une pièce maîtresse de notre détecteur, nous avons constitué une base de données de 4 954 FRs détectés manuellement chez 13 patients. Ce détecteur de FRs a été incorporé au logiciel que nous avons imaginé et créé, baptisé Ladybird, utilisé chez 29 patients pour détecter et traiter plusieurs milliers de FRs. Les avancées techniques et théoriques réalisées au cours de ce travail de thèse nous permettent d'envisager une utilisation à grande échelle de nos outils. Notre objectif est que les équipes médicales puissent en bénéficier directement, dans leur routine diagnostic. Un brevet a été déposé en vue d'un processus d'industrialisation.Almost a third of epileptic patients are resistant to medication. The only way to cure them is to remove the area of the brain that causes the seizures, called the epileptogenic zone (EZ). To locate this area, it is sometimes necessary to carry out stereo-electroencephalography (SEEG) investigations. SEEG consists of implanting intracerebral electrodes in the patient, who remains in hospital for about ten to fifteen days. During this period, the patient's intracerebral activity is continuously recorded on more than a hundred recording channels distributed in the brain structures suspected of being involved in the epileptogenic network. The analysis of the EEG signal by neurologists is a crucial step in the diagnosis, but the amount of data generated is tremendous. As a result, only a small fraction of the recordings can be analyzed by medical teams, who focus mainly on activity during and immediately surrounding seizures. To characterise the extent and dynamics of the epileptogenic network, neurologists also study interictal markers. But some of these biomarkers are impossible to detect manually. The first objective of this interdisciplinary thesis work was to establish new methods to efficiently and automatically detect intercritical markers, namely interictal epileptic discharges (IEDs) and in particular fast ripples (FRs). The second objective was to define and describe the interest of recording pathophysiological markers of epilepsy using micro-electrodes, whereas most studies until now used classical macro-electrodes. Finally, the third objective was focused on FRs, with the idea to better understand their origin, emergence and involvement in the pathology. Our teams use hybrid electrodes that allow for a multi-scale recording of the brain signal of patients. These electrodes are made up of macro-channels allowing the recording of the activity of large neuronal populations and micro-channels capable of capturing much more focal signals, down to the scale of single neuron activity. We have built an automatic IED detector based on a new method of processing the image-transformed signal using a technique we call Convolutional Kernel Density Estimation (CKDE). We also developed an automatic FR detector based on a three-step, CNN-based, ecological approach, mimicking the work of the neurologist. All these tools have been incorporated into graphical user interfaces (GUIs) that combine the different functionalities for easy and efficient use. The detection of IEDs by CKDE offers proof of concept that a pixel-oriented analysis of EEG activity can be used as a strategy to detect interictal markers. We evaluated this method on 10 minutes of recordings in a patient. Fifteen IEDs were automatically detected, of which 13 were true positives and 2 false positives. However, our main results concern the detection of FRs, which would have the greatest potential in the diagnosis of drug-resistant epilepsies. To train the CNN, which is a key component of our detector, we built a database of 4,954 manually detected FRs in 13 patients at both the EEG-macro and the EEG-micro scales. This multi-scale FR detector was incorporated into the software we designed, called Ladybird, which was used in 29 patients to detect and treat several thousand FRs. The technical and theoretical advances made during this thesis allow us to consider a large-scale use of our tools. Our objective is that medical teams can benefit directly from them, in their diagnostic routine. A patent has been filed in view of an industrialization process

    A Dual-Process Model of Response Inhibition: Insights from a Neurocognitive Perspective

    Get PDF
    Perhaps the most critically important cognitive mechanism for survival and social cohesion is the ability to withhold an action that has been rendered maladaptive or inappropriate by altered environmental demands. There is a large body of empirical research investigating this process, which is commonly referred to as response inhibition, but which in most instances more precisely could be termed reactive inhibition because it constitutes only one element of the overall inhibition of an action. Alongside reactive inhibition, though, and certainly of at least equally import, is the capacity to recognise erroneous stimulus-response patterns in one’s own behaviour and to remediate them where they arise. This has been termed proactive inhibition and has received substantially less experimental interest until very recently, despite almost certainly contributing to overall response inhibition. Although these two cognitive mechanisms, reactive and proactive inhibition, are necessarily interdependent, they are representationally distinct and are therefore likely implemented by separate biological and cognitive processes. The basal ganglia are largely responsible for the coordination of motor control, and its neural connections to the motor and frontal cortices plan, select, and direct any intended movement, and indeed certain unintended movements also. Owing to an incomplete physiological characterisation of this circuitry until only the last decade, a critical re- evaluation of those motor functions that rely on computational cognition is germane. It is likely that reactive inhibition recruits internal basal ganglia pathways, perhaps in accordance with the classical dual-organisation model of direct and indirect pathways, because it is principally a motor function; proactive inhibition, on the other hand, requires cognitive computation, either consciously or not, and, therefore, may recruit a recently-described hyperdirect pathway that connects the basal ganglia to a prefrontal neural population that has previously been associated with overall response inhibition, but whose role has been theoretically inconsistent with motor models of inhibition because prefrontal regions are associated with higher cognitive functions and not motor function. With these limitations in mind, in this thesis, I present the experimental findings of four empirical investigations into the neurocognitive architecture of proactive inhibition using updated models in order to revise the understanding of response inhibition and, in particular, the role and underlying properties of proactive inhibition, which we operationalise as post- error slowing (PES) of reaction time. In the first study (N = 264), we investigated the role of two dopaminergic single- nucleotide polymorphisms (DRD1 rs686 and DRD2 rs1800497) which are differentially expressed along basal ganglia pathways in behavioural performance on a Go/No-Go task (the Sustained Attention to Reaction Time task, SART). We found that in those with a higher ratio of D1:D2 receptors (i.e., more rs686 A and rs1800497 T alleles) PES was engaged to a higher degree and that older age magnified this genetic effect (p < .001). In addition, we observed an interaction between age and a general factor of intelligence, g, on PES, whereby older age and lower estimates of g predicted higher recruitment of PES (p < .001). This supports the hypothesis that proactive inhibition appears to be a naturally-occurring compensatory mechanism which manifests in individuals whose reactive inhibition may be suboptimal, and indicates that the extent to which PES is engaged depends on increased dopamine D1 and decreased D2 neurotransmission. The neural generators of overall response inhibition are well described, but very little effort has been given to proactive processes. If reactive inhibition is largely motoric, then its sources can be localised using various techniques that image neural regions using haemodynamic response, but since proactive inhibition is largely cognitive, it is necessary to use other methods. To investigate the cognitive architecture of proactive inhibition we used electroencephalography (EEG). To do this, we use stimulus- and response- locked neural activity to compare the four major accounts of PES. These accounts each have wide support, explain behavioural data, and can be simulated using computational methods. We administered the SART once again to N = 100 healthy young adults and recorded their brain activity using EEG. Our results provide support for an attentional account of PES that supposes errors disturb, or disorient, attentional processing on subsequent trials indexed by the anterior N1. The N1 was significantly blunted by errors (p = .020) and the post-error N1 was correlated with magnitude of PES (p = .016). In addition, we provide additional support for our previous findings indicating an effect of age and g on PES. Here, we find that the post-error N1 diminishes with natural ageing, however, higher estimated g seemed to rescue these age-related deficits (p < .0001). These results bring into question our previous hypothesis that PES is a compensatory mechanism. Rather, it may be a consequence of disruptions to processing that incidentally improve response inhibition as a function of that disruption which offsets the initiation of response execution. Our third study was conducted to investigate the potential efficacy of neurostimulation techniques in the modulation of response inhibition and other cognitive and behavioural functions using transcranial direct current stimulation (tDCS). This study had two experiments. The first investigated whether such functions could be modulated, and the second investigated the nature of that modulation, namely, whether it could be attributed to neuroplastic induction measured by changes to motor evoked potentials using transcranial magnetic stimulation. In the first experiment, our participants (N = 56) attended three sessions, a baseline session followed the following day by single-blind, randomly allocated stimulation testing sessions separated by two days, one with a sham control, and the other with active anodal tDCS to the motor cortex. We administered a Simple and Choice Reaction Time (RT) task, the Inspection Time task, and the SART. This battery allows us to disambiguate perceptual, motor, and cognitive elements of a physical action. We observed no effect on either RT or Inspection Time and observed an effect on the proactive process on the SART (p = .002), such that PES was engaged to a smaller degree after active stimulation compared to both baseline and the sham condition. Likewise, we observed somewhat quicker RT in the SART under active stimulation (p = .073), likely because of the absence of PES, as well as more errors (p = .026), potentially indicating that PES may protect against failures of response inhibition. We attribute these results to the location of the cathode, over the right supraorbital region, roughly above the right inferior frontal gyrus. The anode in tDCS is thought to synchronise neural activity and induce long-term potentiation-like neuroplasticity, whereas the necessary cathode is thought to disrupt such synchronicity. As such, we may have disrupted prefrontal cortical functioning briefly, which in turn eroded proactive functioning. This provides reasonably strong support for frontal regions being implicated in proactive, but not necessarily reactive, inhibition, although we cannot conclude this since overall response inhibition was somewhat disrupted. The final study addresses the theoretical and conceptual limitations in existing response inhibition tasks by implementing a recent Bayesian Ψ adaptive staircase (Livesey & Livesey, 2016) in novel instantiations of two Stop-Signal Tasks (SSTs) that we developed for the purpose of directly observing behavioural proactive inhibition in two forms that are explicitly separable to the reactive process. The Ψ staircase provides an algorithm which allows for rapid estimation of SSRT in very few trials, the importance of which lies in the populations whose response inhibition and behavioural and motoric regulation are impaired due to psychopathology or neurodegeneration. Task duration is a considerable limitation on reliable estimates of performance on such tasks, and particularly in such populations. We administered four tasks (two SSTs and two Go/No-Go tasks) to N = 123 healthy young adults. We included a manipulation that cued the probability of a Stop/No-Go trial in the two SSTs and one of the Go/No-Go tasks, which was a modified form of the SART. These two probability conditions allow us to compare RT in each condition on Go trials, under the assumption that longer RT in higher p(Stop/No-Go) conditions indicates a predictive form of proactive inhibition. This is distinct from the remedial form, post-error slowing, that can still be observed in the tasks. We report two important findings. The first is that the Ψ staircase is highly successful in rapidly converging on reliable estimates of SSRT in as few as 20 stop trials, which could prove useful in designing considerably shorter tasks in the future without sacrificing reliability. Secondly, we show that predictive and remedial forms of proactive inhibition are consistently engaged in all tasks, potentially providing another avenue for thinking about proactive inhibition in the future. Thirdly, we show that estimates of SSRT, which aims to assess reactive inhibition, are robust against proactive inhibition. Taken together, the conclusions reached in this thesis represent a critical update of the neurobiology that underlies newly-discretised cognitive processes that contribute to response inhibition, as well as their psychophysiological characteristics. We have demonstrated that proactive inhibition at least partly reflects a compensatory mechanism that appears to be naturally-occurring in individuals whose reactive processes may be insufficient for psychological and biological reasons as well as individual differences in intellectual capacity. Furthermore, we present and validate a novel, theoretically cogent task paradigm to measure what we posit are discrete processes within the proactive process: remedial and predictive proactive inhibition. Given what appears to be a naturally-occurring compensatory mechanism alongside post-error slowing that corresponds to the timing of a pre-error negative inflection in electrophysiological recordings, this work raises fascinating questions about the distinction between conscious, preconscious, and subconscious brain states and their effect on behaviour.Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 202

    Delayed effects and critical transitions in climate models

    Get PDF
    There is a continuous demand for new and improved methods of understanding our climate system. The work in this thesis focuses on the study of delayed feedback and critical transitions. There is much room to develop upon these concepts in their application to the climate system. We explore the two concepts independently, but also note that the two are not mutually exclusive. The thesis begins with a review of delay differential equation (DDE) theory and the use of delay models in climate, followed by a review of the literature on critical transitions and examples of critical transitions in climate. We introduce various methods of deriving delay models from more complex systems. Our main results center around the Saltzman and Maasch (1988) model for the Pleistocene climate (`Carbon cycle instability as a cause of the late Pleistocene ice age oscillations: modelling the asymmetric response.' Global biogeochemical cycles, 2(2):177-185, 1988). We observe that the model contains a chain of first-order reactions. Feedback chains of this type limits to a discrete delay for long chains. We can then approximate the chain by a delay, resulting in scalar DDE for ice mass. Through bifurcation analysis under varying the delay, we discover a previously unexplored bistable region and consider solutions in this parameter region when subjected to periodic and astronomical forcing. The astronomical forcing is highly quasiperiodic, containing many overlapping frequencies from variations in the Earth's orbit. We find that under the astronomical forcing, the model exhibits a transition in time that resembles what is seen in paleoclimate records, known as the Mid-Pleistocene Transition. This transition is a distinct feature of the quasiperiodic forcing, as confi rmed by the change in sign of the leading nite-time Lyapunov exponent. Additional results involve a box model of the Atlantic meridional overturning circulation under a future climate scenario and time-dependent freshwater forcing. We find that the model exhibits multiple types of critical transitions, as well as recovery from potential critical transitions. We conclude with an outlook on how the work presented in this thesis can be utilised for further studies of the climate system and beyond.European Commissio

    Towards an Understanding of Tinnitus Heterogeneity

    Get PDF

    Identity and Positioning in Algerian and Franco-Algerian Contemporary Art

    Get PDF
    Identity and belonging increasingly feature as themes in the work of contemporary artists, a focus that seems particularly felt by those artists who either personally or through their families have experienced dispersal and migration. The thesis explores how fourteen Algerian and Franco-Algerian artists position themselves and are positioned by others to identity and community. The difficult intertwined histories of Algeria and France fraught with the consequences of colonisation, the impact of migration, and, in Algeria, civil war, provides a rich terrain for the exploration of identity formation. Positionality theory is used to analyse the process of identity formation in the artists and how this developed over the course of their careers and in their art. An important part of the analysis is concerned with how the artists positioned themselves consciously or inadvertently to fixed or fluid conceptions of identity and how this was reflected in their artworks. The thesis examines the complex politics of identity and belonging that extends beyond nationality and diaspora and implicates a range of other identifications including that of class, ethnicity, gender, sexuality and career choice. The research addresses a gap in contemporary art scholarship by targeting a specific group of artists and their work and examining how they negotiate, in an increasingly globalised world, their relationship to identity including nationality and diaspora. The thesis foregrounds the ways in which this negotiation interacts with their careers, their art and the art market. The thesis begins with an outline of the methodological approach. Positioning to identity is then examined in the background, education, professional development and art of three international artists, Kader Attia, Adel Abdessemed and Saâdane Afif. Analysis then focuses on the artwork of the eleven remaining artists through the themes of history and memory, journey and narrative and gendered space

    Towards an Understanding of Tinnitus Heterogeneity

    Get PDF

    Augmentation of Brain Function: Facts, Fiction and Controversy. Volume III: From Clinical Applications to Ethical Issues and Futuristic Ideas

    Get PDF
    The final volume in this tripartite series on Brain Augmentation is entitled “From Clinical Applications to Ethical Issues and Futuristic Ideas”. Many of the articles within this volume deal with translational efforts taking the results of experiments on laboratory animals and applying them to humans. In many cases, these interventions are intended to help people with disabilities in such a way so as to either restore or extend brain function. Traditionally, therapies in brain augmentation have included electrical and pharmacological techniques. In contrast, some of the techniques discussed in this volume add specificity by targeting select neural populations. This approach opens the door to where and how to promote the best interventions. Along the way, results have empowered the medical profession by expanding their understanding of brain function. Articles in this volume relate novel clinical solutions for a host of neurological and psychiatric conditions such as stroke, Parkinson’s disease, Huntington’s disease, epilepsy, dementia, Alzheimer’s disease, autism spectrum disorders (ASD), traumatic brain injury, and disorders of consciousness. In disease, symptoms and signs denote a departure from normal function. Brain augmentation has now been used to target both the core symptoms that provide specificity in the diagnosis of a disease, as well as other constitutional symptoms that may greatly handicap the individual. The volume provides a report on the use of repetitive transcranial magnetic stimulation (rTMS) in ASD with reported improvements of core deficits (i.e., executive functions). TMS in this regard departs from the present-day trend towards symptomatic treatment that leaves unaltered the root cause of the condition. In diseases, such as schizophrenia, brain augmentation approaches hold promise to avoid lengthy pharmacological interventions that are usually riddled with side effects or those with limiting returns as in the case of Parkinson’s disease. Brain stimulation can also be used to treat auditory verbal hallucination, visuospatial (hemispatial) neglect, and pain in patients suffering from multiple sclerosis. The brain acts as a telecommunication transceiver wherein different bandwidth of frequencies (brainwave oscillations) transmit information. Their baseline levels correlate with certain behavioral states. The proper integration of brain oscillations provides for the phenomenon of binding and central coherence. Brain augmentation may foster the normalization of brain oscillations in nervous system disorders. These techniques hold the promise of being applied remotely (under the supervision of medical personnel), thus overcoming the obstacle of travel in order to obtain healthcare. At present, traditional thinking would argue the possibility of synergism among different modalities of brain augmentation as a way of increasing their overall effectiveness and improving therapeutic selectivity. Thinking outside of the box would also provide for the implementation of brain-to-brain interfaces where techniques, proper to artificial intelligence, could allow us to surpass the limits of natural selection or enable communications between several individual brains sharing memories, or even a global brain capable of self-organization. Not all brains are created equal. Brain stimulation studies suggest large individual variability in response that may affect overall recovery/treatment, or modify desired effects of a given intervention. The subject’s age, gender, hormonal levels may affect an individual’s cortical excitability. In addition, this volume discusses the role of social interactions in the operations of augmenting technologies. Finally, augmenting methods could be applied to modulate consciousness, even though its neural mechanisms are poorly understood. Finally, this volume should be taken as a debate on social, moral and ethical issues on neurotechnologies. Brain enhancement may transform the individual into someone or something else. These techniques bypass the usual routes of accommodation to environmental exigencies that exalted our personal fortitude: learning, exercising, and diet. This will allow humans to preselect desired characteristics and realize consequent rewards without having to overcome adversity through more laborious means. The concern is that humans may be playing God, and the possibility of an expanding gap in social equity where brain enhancements may be selectively available to the wealthier individuals. These issues are discussed by a number of articles in this volume. Also discussed are the relationship between the diminishment and enhancement following the application of brain-augmenting technologies, the problem of “mind control” with BMI technologies, free will the duty to use cognitive enhancers in high-responsibility professions, determining the population of people in need of brain enhancement, informed public policy, cognitive biases, and the hype caused by the development of brain- augmenting approaches
    corecore