This dissertation explores the role of brainstem structures in the development and expression of generalized tonic-clonic seizures. The functional consequences of brainstem seizures are investigated using the kindling paradigm in order to understand the behavioral and cognitive effects of generalized seizures. <BR><BR> I begin by investigating the general characteristics of brainstem kindling. The first experiment demonstrates that certain brainstem sites are indeed susceptible to kindling and begins to delineate the features that distinguish brainstem seizures from those evoked at other brain regions. Further investigation of the EEG signal features using wavelet analysis reveals that changes in the spectral properties of the electrographic activity during kindling include significant changes to high-frequency activity and organized low-frequency activity. I also identify transitions that include frequency sweeps and abrupt seizure terminations. The changing spectral features are shown to be critically associated with the evolution of the kindled seizures and may have important functional consequences. The surprising responsiveness of some brainstem structures to kindling forces us to reconsider the overall role of these structures in epileptogenesis as well as in the healthy dynamical functioning of the brain. <BR><BR> In order to study the functional consequences, a series of experiments examines the changes in behavior, cognition and affect that follow these brainstem seizures. Although the results show no effects on spatial learning or memory, there are significant and complex effects on anxiety- and depression-like behavior that appear to be related to motivation. In order to further study the cognitive effects, a second set of behavioral experiments considers how context (i.e., the environment) interacts with the behavioral changes. The results indicate that changes in affect may only be apparent when choice between seizure-related and seizure-free contexts is given, suggesting that the environment and choice can play key roles in the behavioral consequences of seizures. This thesis also includes an appendix that applies synchrotron imaging to investigate the anatomical consequences of electrode implantation in kindling and shows that significantly increased iron depositions occur even with purportedly biocompatible electrodes widely used in research and clinical settings. <BR><BR> Examination of the role of brainstem structures in generalized seizures in this dissertation offers new perspectives and insights to epileptogenesis and the behavioral effects of epilepsy. The changes in EEG features, behavior, affect and motivation observed after brainstem seizures and kindling may have important clinical implications. For example, the results suggest a need to reexamine the concept of psychogenic seizures, a potential connection to Sudden Unexplained Death in Epilepsy (SUDEP), and the contribution of environmental factors. It is hoped that these findings will help elucidate the complex issues involved in understanding and improving the quality of life for people with epilepsy.

This study focuses on realization of a Brain Computer Interface (BCI)for the paralyzed to control assistive environmental devices. For this purpose, different motor imagery tasks are classified using different signal processing methods. Specifically, band-pass filtering, Laplacian filtering, and common average reference (CAR) filtering areused to enhance the EEG signal. For feature extraction / Common Spatial Pattern (CSP), Power Spectral Density (PSD), and Principal Component Analysis (PCA) are tested. Linear Feature Normalization (LFN), Gaussian Feature Normalization (GFN), and Unit-norm Feature Vector Normalization (UFVN) are studied in Support Vector Machine (SVM) and Artificial Neural Network (ANN) classification. In order to evaluate and compare the performance of the methodologies, classification accuracy, Cohen&rsquo / s kappa coefficient, and Nykopp&rsquo / s information transfer are utilized. The first experiments on classifying motor imagery tasks are realized on the 3-class dataset (V) provided for BCI Competition III. Also, a 4-class problem is studied using the dataset (IIa) provided for BCI Competition IV. Then, 5 different tasks are studied in the METU Brain Research Laboratory to find the optimum number and type of tasks to control a motor imagery based BCI. Thereafter, an interface is designed for the paralyzed to control assistive environmental devices. Finally, a test application is implemented and online performance of the design is evaluated.

Simulation-based training has gained widespread attention recently as a response to drawbacks associated with traditional training approaches, such as high training costs (instructors, equipment, etc.), high risks (e.g. pilot training), and ethical issues (e.g. medical training), as well as a lack of availability of certain training environments (e.g. space exploration). Apart from their target training domains, many of aspects of simulations differ, such as their degree of physical realism (fidelity), scenarios (e.g. story), and pedagogical aspects (e.g. after-action reviews and collaborative learning). Among those aspects, designers have mostly focused on developing high-fidelity simulations with the expectation of increasing the effectiveness of training. However, some authors suggest that the above belief is a myth as researchers have failed to identify a linear relationship between the (physical) fidelity and training effectiveness of simulations.  Most researchers have therefore evaluated the correspondence between the behaviours of trainees in both real world and simulated contexts, however, the existing methods of simulation validation using behavioural measures have a number of drawbacks, such as the fact that they do not address certain complex phenomena of skills acquisition. Bridging the above knowledge gap, this research reports on empirical investigations using an improved methodology for validating training simulations. This research includes an investigation of the user experience of trainees, with respect to the acceptance of virtual scenarios provoking a similar psychophysiological response as in real world scenarios, and the training potential of simulations with respect to the positive transfer of training from a simulator to real world operational contexts. The most prominent features of the proposed methodology include the use of psychophysiological measures in addition to traditional behavioural measures and the use of natural (quasi-) experiments. Moreover, its conceptual framework was influenced by contemporary theories in cognitive science (e.g. constructivism and embodied cognition). The results of this research have several important theoretical and methodological implications, involving, for example, the dependency of the effectiveness of simulations on the perceived realism of trainees, which is more embodied than has been predicted by previous researchers, and the requirement of several different types/levels of adaptive training experience, depending on the type of trainee. / Träning i simulatorer har på senare år fått ökad uppmärksamhet som en respons på problem och svårigheter förknippade med traditionella träningsansatser, såsom höga kostnader (instruktörer och utrustning, etc.), hög risk (t.ex. träning av piloter), och etiska aspekter (t.ex. träning av kirurger), likaväl som avsaknaden av träningsmöjligheter och miljöer (t.ex. forskning om rymden). Bortsett från vad som specifikt tränas så skiljer sig simuleringar åt i ett flertal olika aspekter såsom fysisk realism (eng. fidelity), scenarier (handling) och pedagogiska aspekter (t.ex. genomgång efter övning och kollaborativt lärande).  Bland dessa aspekter så har designers ofta fokuserat att utveckla simuleringar med hög realism med förväntningen att detta ska göra träningen mer effektiv. Litteraturen antyder dock att denna föreställning inte stämmer och att de flesta simuleringar med hög realism inte har lyckats uppnå denna målsättning. En slutsats är därför att det finns ett behov av metoder som kan validera potentialen hos simuleringar avsedda att stödja träning – redan innan dessa används. Enligt litteraturen så är utbildningspotentialen hos en simulering starkt kopplad till hur väl den psykologiska effekten en simulering har, stämmer överens med en verklig upplevelse. Forskning har emellertid identifierat ett flertal svagheter hos existerande ansatser för att validera simuleringar; de är oftast baserade på prestations- och/eller subjektiva mätningar; de har fokuserat en eller ett fåtal psykologiska aspekter; och de bygger på traditionella teorier. Baserat på resultat från studier av en kör-simulator presenteras och föreslås i denna avhandling ett förbättrat ramverk för utvärdering. De mest centrala egenskaperna hos det föreslagna ramverket inbegriper användandet av psyko-fysiologiska mått tillsammans med mer traditionella mått; det konceptuella ramverket bygger på samtida teoretiska ansatser (tex konstruktivism och kroppslig kognition); samt användandet av fält (kvasi-) experiment. Utöver uppnåendet av uppsatta mål för forskningen så har resultaten ett flertal teoretiska och metodologiska implikationer. Bland dessa återfinns beroendet mellan effektiviteten hos en simulering och den upplevelse av realitet som de tränade har, vilken är mer grundläggande än vad som rapporterats i tidigare forskning, samt kravet på flera och olika typer av anpassning av träningsupplevelse för den tränade för att förhöja potentialen hos träningssimulatorer. / SIDA Funded National e-Learning Centre Project at the University of Colombo School of Computing, Sri Lanka

Στη συγκεκριμένη μεταπτυχιακή εργασία γίνεται ανάλυση των ηλεκτροεγκεφαλογραφικών καταγραφών επιληπτικών ασθενών με βάση την κλασματική διάσταση για τον εντοπισμό της έναρξης των επιληπτικών κρίσεων καθώς και για την ανίχνευση των επερχόμενων επιληπτικών κρίσεων. Πιο συγκεκριμένα, χρησιμοποιούνται τέσσερις μέθοδοι υπολογισμού της κλασματικής διάστασης στο πεδίο του χρόνου. Πραγματοποιείται μία συγκριτική μελέτη των συγκεκριμένων μεθόδων χρησιμοποιώντας δύο συνθετικά σήματα γνωστής κλασματικής διάστασης και στη συνέχεια οι μέθοδοι εφαρμόζονται σε ηλεκτροεγκεφαλογραφικές καταγραφές ασθενών που πάσχουν από επιληψία. Η συγκεκριμένη εργασία αποδεικνύει ότι όλες οι μέθοδοι μπορούν και εντοπίζουν την έναρξη των επιληπτικών κρίσεων ενώ η στατιστική ανάλυση δείχνει ότι κάποιες από αυτές τις μεθόδους μπορούν να χρησιμοποιηθούν και ως δείκτες πρόβλεψης των επερχόμενων επιληπτικών κρίσεων. Επίσης, διαπιστώνεται ότι ανάλογα με το είδος των ηλεκτροεγκεφαλογραφικών καταγραφών, το μέγεθος του παραθύρου και τη ζώνη διέλευσης του φίλτρου τα αποτελέσματα της κλασματικής διάστασης που προκύπτουν επηρεάζονται. / Τhe fractal dimension is a powerful tool in the analysis of electroencephalograms. In this work, four methods of estimating the fractal dimension of electroencephaolographic recordings of epileptic patients directly in the time domain are analyzed and compared. The analysis is performed over both synthetic data and real recordings of epileptic patients. The effects of the type of recordings, the window size and the frequencies in the passband filter are examined. This study shows that the four methods detect the beginning of the epileptic seizures, while the statistic analysis proves that some of these methods can be used for the prediction of the next seizures.

L'estimation de l'état mental d'un individu sur la base de son activité cérébrale et de ses activités physiologiques résultantes est devenue l'un des challenges des interfaces cerveau-machine (ICM) dites passives, dans le but notamment de répondre à un besoin en neuroergonomie. Ce travail de thèse se focalise sur l'estimation des états de fatigue et de charge mentale. Son objectif est de proposer des chaines de traitement efficaces et réalistes dans leur mise en œuvre. Ainsi, un des points à l'étude a été la modulation des indicateurs de charge ainsi que la robustesse des performances de classification en fonction du temps passé sur une tâche (TPT). L'impact de la charge et du TPT sur les marqueurs d'état attentionnel a aussi été évalué. Pour ce faire, un protocole expérimental a été mis en œuvre afin de recueillir les signaux électro-encéphalographiques (EEG), cardiaques (ECG) et oculaires (EOG) de participants volontaires sains lors de la réalisation prolongée d'une tâche combinant charge en mémoire de travail et attention sélective. Des chaînes de traitement performantes incluant une étape de filtrage spatial et une classification supervisée ont été mises en place afin de classer au mieux ces états. La pertinence de plusieurs marqueurs électrophysiologiques a été comparée, notamment l'activité EEG spontanée et les potentiels évoqués (PEs), ainsi que différentes étapes de prétraitement dont les méthodes de filtrage spatial pour PEs. Des effets d'interactions ont été mis au jour entre les différents états mentaux, dont un effet négatif du TPT sur les performances en classification de la charge mentale lorsque l'on utilise des marqueurs mesurant la puissance moyenne de l'EEG dans des bandes de fréquence d'intérêt. La chaîne basée sur les PEs est en revanche robuste à cet effet. Une comparaison du type de stimuli utilisables pour éliciter les PEs a révélé que des stimuli tâche-indépendants permettent tout de même d'obtenir des performances très élevées, ce qui montre leur pertinence pour une implémentation en situation réelle. En perspective seront présentés des travaux en cours visant à mettre en évidence des marqueurs de charge mentale robustes à la tâche, ainsi que l'utilité des potentiels évoqués auditifs en paradigme de simple stimulus. / Mental state estimation on the basis of cerebral activity and its resulting physiological activities has become a challenge for passive Brain-Computer Interfaces (BCI), in particular to address a need in neuroergonomics. This thesis work focuses on mental fatigue and workload estimation. Its purpose is to provide efficient and realistic processing chains. Thus, one issue was the modulation of workload markers as well as classification performance robustness depending on time-on-task (TOT). The impact of workload and TOT on attentional state markers was also assessed. For those purposes, an experimental protocol was implemented to collect the electroencephalographic (EEG), cardiac (ECG) and ocular (EOG) signals from healthy volunteers as they performed for a prolonged period of time a task that mixes working memory load and selective attention. Efficient signal processing chains that include spatial filtering and classification steps were designed in order to better estimate these mental states. The relevance of several electrophysiological markers was compared, among which spontaneous EEG activity and event-related potentials (ERPs), as well as various preprocessing steps such as spatial filtering methods for ERPs. Interaction effects between mental states were brought to light. In particular, TOT negatively impacted mental workload estimation when using power features. However, the chain based on ERPs was robust to this effect. A comparison of the type of stimuli that can be used to elicit the ERPs revealed that task-independent probes still allow very high performance, which shows their relevance for real-life implementation. Lastly, ongoing work that aims at assessing task-robust workload markers, as well as the usefulness of auditory ERPs in a single-stimulus paradigm will be presented as prospects.

This master thesis deals with classification of sleep stages on the base of polysomnographic signals. On several signals was performed analysis and feature extraxtion in time domain and in frequency domain as well. For feature extraxtion was used EEG, EOG and EMG signals. For classification was selected classification models K-NN, SVM and artifical neural network. Accuracy of classifation is different depending on used method and spleep stages split. The best results achieved classification among stages Wake, REM, and N3, with neural network usage. In this case the succes was 93,1 %.

This thesis deals with wavelet analysis of sleep electroencephalogram to sleep stages scoring. The theoretical part of the thesis deals with the theory of EEG signal creation and analysis. The polysomnography (PSG) is also described. This is the method for simultaneous measuring the different electrical signals; main of them are electroencephalogram (EEG), electromyogram (EMG) and electrooculogram (EOG). This method is used to diagnose sleep failure. Therefore sleep, sleep stages and sleep disorders are also described in the present study. In practical part, some results of application of discrete wavelet transform (DWT) for decomposing the sleep EEGs using mother wavelet Daubechies 2 „db2“ are shown and the level of the seven. The classification of the resulting data was used feedforward neural network with backpropagation errors.

L'encéphalopathie hypoxique ischémique néonatale (EHI) reste la cause principale de mortalité chez le nouveau-né à terme. Un tiers des survivants vont développer des séquelles neurologiques, dont la paralysie cérébrale (PC), l'épilepsie et un retard intellectuel. Afin d'améliorer leur pronostic, ces nouveau-nés sont soumis à l'hypothermie thérapeutique (HT) qui débute au plus tard 6 heures après la naissance, pour une durée totale de 72 heures, suivie d'un réchauffement graduel (0.5°C/h). Il a été démontré que cette thérapie à effet neuroprotecteur diminue considérablement l'étendue des lésions cérébrales et la fréquence des séquelles neurologiques. Or, des études animales suggèrent que l'hypothermie sans sédation avec opioïdes n'est pas bénéfique. Selon les observations qui ont été réalisées, les porcelets traités avec la thérapie, mais sans l’administration d’analgésique ont manifesté des signes d’instabilités et de tremblements exagérés. On ignorait jusqu’à présent dans quelle mesure ces résultats tirés des expérimentations animales pouvaient être généralisables au nouveau-né. Ainsi, mon projet de maîtrise vise à mieux comprendre les facteurs qui risquent de compromettre les effets bénéfiques de la thérapie de refroidissement, dans le but d’optimiser la neuroprotection et d’améliorer le développement des nourrissons atteints d’EHI. Nous avons comme objectif principal d’évaluer l’association entre les doses d’opioïdes consommées pendant l’HT, le degrée de tremblement, et l’évolution de l’index de discontinuité à l’EEG au fil des 72h de l’HT, du réchauffement et jusqu’à 12 heures post-HT. Pour répondre à l’objectif, nous avons conduit une étude chez 21 nouveau-nés avec EHI soumis à l’HT, et dont les principaux résultats ont montré des associations significatives entre les fortes doses d’opioïdes administrés à l’enfant (r = - 0.493, p = 0.023), les frissons réduits pendant l’HT (r = 0.513, p = 0.017) et l’amélioration du rythme cérébrale d’EEG. Ces résultats sont décrits de manière plus approfondie dans le Chapitre 2 qui présente la version de l’article soumis à la revue Journal of Pediatrics, et le Chapitre 3 qui présente un retour sur la littérature à la lumière de nos trouvailles. Quant au Chapitre 4, nous y élaborons les possibilités de perspectives futures et les retombées cliniques de nos résultats. À long terme, nous espérons que nos travaux permettront l’ouverture d’une nouvelle piste d’amélioration de la neuroprotection, en favorisant systématiquement une meilleure prise en charge de la douleur et du stress induit par le refroidissement. / Neonatal hypoxic-ischemic encephalopathy (HIE) remains the leading cause of death and mortality in the term infant. A third of the survivors will develop neurological sequelae including cerebral palsy (CP), epilepsy and mental retardation. In order to improve their prognosis, these newborns undergo therapeutic hypothermia (TH), which begins no later than 6 hours after birth, maintained for a total duration of 72 hours and followed by gradual rewarming (0.5°C/h). This neuroprotective therapy has been shown to significantly decrease the extent of brain injury and the frequency of neurological sequelae. Results from animal studies revealed that ongoing hypothermia without proper anesthesia is not beneficial. Based on the observations that have been reported, piglets treated with TH with no analgesics have shown signs of instability and excessive tremors. Until now, the extent to which these results from animal experiments could be generalized to the newborn remained unknown. Thus, the purpose of my master’s project was to better understand the clinical factors that may compromise the beneficial effects of TH, in an attempt to optimize neuroprotection and improve the neurological outcome of HIE infants. Our main objective was to assess the associations between opioid doses consumed during TH, shivering recorded during TH, and the evolution of EEG discontinuity index over the course of TH, rewarming and up to 12 hours post-TH. To meet the objective, we conducted a study in 21 newborns with HIE undergoing TH, and the results have shown significant associations between high doses of opioid administered (r = - 0.493, p = 0.023), reduced shivering stress (r = 0.513, p = 0.017) and improved EEG background activity. The key findings of the study are described in more detail in Chapter 2, which presents the original manuscript submitted for publication to the “Journal of Pediatrics”, and Chapter 3, which presents a review of the literature in light of our results. In Chapter 4, we discuss future perspectives and the clinical significance of our results. At last, we hope that our study will open up new avenues for improving neuroprotection, by systematically promoting a better management of pain and cooling-induced stress.

There are several commercial electroencephalography (EEG) devices on the market; however, affordable devices are not versatile for diverse research applications. The purpose of this project was to investigate how to develop a low-cost, portable, single-channel EEG system for a research institute that could be used for neurofeedback-related applications in homecare. A device comparison was intended to examine what system requirements such a system would need to achieve the secondary objective of developing a neurofeedback application that demonstrates the functionalities of the new device. A portable, single-channel EEG device prototype was realized that consisted of an amplifier module called EEG Click, a single-board microcontroller, an electrode cable, some disposable wet electrode pads, and a custom 3D-printed headband. Three pieces of software were developed: firmware for the prototype, two supporting computer applications for data recording, and visual neurofeedback. The neurofeedback application replayed a first-person view roller coaster video at a varying frame rate based on the theta band's mean power spectral density (PSD). The prototype was compared against a commercial device, InteraXon MUSE 2 (Muse). Technical measurements included determining the amplitude-frequency characteristics and signal quality, such as signal-to-noise ratio (SNR), spurious-free dynamic range (SFDR), and total harmonic distortion (THD). Furthermore, four physiological measurements were performed on six human test subjects, aged between 21-31 (mean: 26.0, std: 3.11), to compare the altered brain activity and induced artifacts between the two devices. The four tests were respiratory exercise, head movement exercise, eye movement exercise, and paced auditory serial addition test (PASAT), where each measurement included several epochs with various stimuli. After the recordings, PSD was calculated for each bandpass filtered epoch, then the spectra were split into theta (4-8 Hz), alpha (8-12 Hz), and beta bands (12-30 Hz). The PSD values were averaged within each frequency band, and then these baseline-corrected mean values were the input for the repeated measures ANOVA statistical analysis. Results revealed that the amplitude-frequency characteristic of the prototype was low-pass filter-like and had a smaller slope than Muse's. The prototype's SNR, including and excluding the first five harmonics, was 6 dB higher, while SFDR and THD for the first five harmonics were roughly the same as Muse's. The two devices were comparable in detecting changes in most physiological measurements. Some differences between the two devices were that Muse was able to detect changes in respiratory activity in the beta band (F(8,16) = 2.510, p = .056), while the prototype was more sensitive to eye movement, especially lateral and circular eye movement in theta (F(2,8) = 9.144, p = .009) and alpha (F(2,8) = 6.095, p = .025) bands. A low-cost, portable EEG prototype was successfully realized and validated. The prototype was capable of performing homecare neurofeedback in the theta band. The results indicated it is worth exploring further the capabilities of the prototype. Since the sample size was too small, more complex physiological measurements with more test subjects would be more conclusive. Nevertheless, the findings are promising; the prototype may become a product once. / Det finns flera kommersiella EEG-apparater (elektroencefalografi) på marknaden; däremot är de prismässigt överkomliga apparaterna inte mångsidiga nog för olika forskningsapplikationer. Syftet med detta projekt var att undersöka hur man kan utveckla en billigt, portabelt, enkanaligt EEG-system för ett forskningsinstitut som skulle kunna användas för neurofeedbackrelaterade tillämpningar inom hemsjukvård. En apparatjämförelse var tänkt att undersöka vilka systemkrav ett sådant system skulle behöva uppnå för att realisera det sekundära målet att utveckla en neurofeedback-applikation för att demonstrera den nya apparatens funktioner. En prototyp av en bärbar, enkanalig EEG-apparat skapades som bestod av en förstärkarmodul kallad EEG Click, en enkortsmikrokontroller, en elektrodkabel, några utbytbara våta elektrodkuddar och ett 3D-tryckt specialpannband. Tre mjukvarodelar utvecklades: en firmware för prototypen och två stödjande datorapplikationer, en för datainspelning och en för visuell neurofeedback. Applikationen för neurofeedback spelade upp en berg-och-dalbana för förstapersonsvisning med en varierande bildhastighet baserat på thetabandets effektspektrumet (eng. power spectral density, PSD). Prototypen jämfördes mot en kommersiell apparat, InteraXon MUSE 2 (Muse). Tekniska mätningar inkluderade fastställande av amplitud-frekvensegenskaper och signalkvalitet, såsom signal-brusförhållande (eng. signal-to-noise ratio, SNR), spuriosfritt dynamiskt område (eng. spurious free dynamic range, SFDR) och total harmonisk distorsion (eng. total harmonic distortion, THD). Vidare utfördes fyra fysiologiska mätningar på sex mänskliga deltagare (medelålder: 26,0, std: 3,11) för att jämföra de två apparaterna med avseende på mätningar av den förändrade hjärnaktiviteten och inducerade artefakter. De fyra testerna var andningsövningar, huvudrörelseövningar, ögonrörelseövningar, och paced auditory serial addition test (PASAT), där varje mätning innehöll flera epoker med olika stimuli. Efter inspelningarna beräknades PSD för varje bandpassfiltrerad epok, sedan delades spektrumet upp i theta-, alpha- och beta-band. Medelvärdet för PSD-värdena kalkylerades för varje frekvensband och dessa baseline-korrigerade medelvärden var indata till den beroende ANOVA statistisk analysen. Resultaten avslöjade att amplitud-frekvenskarakteristiken för prototypen var lågpassfilterliknande och hade en mindre lutning än Muses. Prototypens SNR, inklusive och exklusive de första fem harmonik, var 6 dB högre, medan SFDR och THD för de första fem övertonerna var ungefär desamma som Muses. De två apparaterna var jämförbara när det gäller att upptäcka förändringar i de flesta fysiologiska mätningar. Vissa skillnader mellan de två apparaterna var att Muse kunde upptäcka förändringar i andningsaktivitet i beta-bandet (F(8,16) = 2,510, p = 0,056), medan prototypen var mer känslig för ögonrörelser, särskilt de laterala och cirkulära ögonrörelser, i theta-bandet (F(2,8) = 9,144, p = 0,009) och alfa-bandet (F(2,8) = 6,095, p = 0,025). Prototypen var generellt mer känslig för grundläggande hjärnaktivitet, buller från omgivningen och artefakter. Sammanfattningvis konstruerades en billig, bärbar EEG-prototyp, vilketvaliderades framgångsrikt. Den anpassade enheten kunde utföra neurofeedback för hemsjukvård. Resultaten visade att det är värt att utforska prototypens möjligheter ytterligare. Eftersom stickprovet var relativt litet skulle mer komplexa fysiologiska mätningar med flera testpersoner krävas för att fastställa framtida användningsområden. Icke desto mindre är resultaten lovande; prototypen kan bli en produkt en gång.

Despite a high proportion of the population experiencing traumatic events within their lifetime, the number of individuals who go on to develop posttraumatic stress disorder (PTSD) is comparatively small; herein highlighting the importance of individual differences in imparting risk and resilience towards the development and maintenance of PTSD. Existing literature illustrates that biological and ecological factors are important in predicting PTSD development, with pathological vulnerabilities excepting their effects at pre- peri- and post trauma stages. Whilst cognitive and emotion based models of PTSD account for the role of a minority of known pre-trauma risk factors, individual differences in peri- and post trauma processes are held as critical to the development of PTSD. The broad range of risk factors implicated in the empirical literature, and necessity of traumatic exposure to PTSD, implicates the utility of a diathesis-stress conceptualisation of PTSD development. The current thesis employed an analogue VR-trauma paradigm to investigate the respective importance of vulnerability factors at each stage, in the prediction of analogue PTSD symptoms (memory problems, startle responses, re-exposure fear habituation), whilst measuring affective and electrophysiological concomitance. Findings supported the importance of peri-traumatic responses in the prediction of PTSD, where present, showing increased predictive capacities over pre- and post-trauma factors. Biological and ecological factors also illustrated important predictive associations, with genetic SNPs implicated in reflex startle and cardiac responses towards intrusive memories. Moreover, peri-traumatic HR decelerations and accelerations mediated the association between pre-trauma factors and cued recall inaccuracy and intrusion severity respectively. Results support existing cognitive and emotional models in their emphasis on peri-traumatic processes but suggest the added utility of a diathesis stress conceptualisation of the development of PTSD, in highlighting the importance of pre-trauma biological and ecological risk and resilience factors.