Measuring prefrontal cortex response to virtual reality exposure therapy in freely moving participants

Virtual Reality Exposure Therapy has demonstrated efficacy in the treatment of phobias; yet little is known about its underlying neural mechanisms. Neuroimaging studies have demonstrated that both traditional exposure therapy and virtual reality exposure therapy normalise brain activity within a prefrontal - amygdalar fear circuit after the treatment. However, the previous studies employed technologies that perhaps impact on ecological validity and naturalness of experience. Moreover, there are no studies investigating what is happening in the brain within a virtual reality session. This PhD takes a multidisciplinary approach and draws upon research areas of cognitive neuroscience, neuropsychology, and virtual reality. The approach is twofold - developmental and experimental. A key methodological objective was to maximise ecological validity by allowing freedom of movement and sight of one’s own body. This was approached by combining wearable fNIRS within Immersive Projection Technology (IPT). The stimulus was adapted from a classic VR experiment - Pit Room. The scope of this PhD includes three experiments. The first pilot experiment tested the potential of combining the wearable Functional Near-Infrared Spectroscopy (fNIRS) device – NIRSport, with virtual reality (VR) display - CAVE-like Immersive Projection Technology (IPT) system – Octave. The aim was to test the feasibility of the protocol in terms of the design, integration of technology, and signal to noise ratio in the Pit Room study, which involved measuring brain response during exposure to heights in virtual reality. The study demonstrated that brain activity could be measured in IPT without a significant signal interference. Although there was no significant change in brain activity during exposure to virtual heights, the study found trends toward increased HbO in the prefrontal cortex. The second study investigated the brain activity indicative of fear inhibition and cognitive reappraisal within a single session of VRET in healthy controls. The heart rate was also measured as an indicator of emotional arousal (fear response) during the VRET session. 27 healthy volunteers were exposed to heights in virtual reality. Changes in oxygenated haemoglobin concentration in the prefrontal cortex were measured in three blocks using a wireless fNIRS, and heart rate was measured using a wireless psychophysiological monitor. Results revealed increased HbO concentration in the DLPFC and MPFC during exposure to the fear-evoking VR, consistent with fear inhibition and cognitive reappraisal measured in previous neuroimaging studies that had not used VR. Within-session brain activity was measured at much higher temporal resolution than in previous studies. Consistent with previous studies, a trend showed an increase of brain activity in the DLPFC indicative of cognitive reappraisal at the beginning of the session. Then additionally the MPFC was activated consistent with fear inhibition. The heart rate showed a trend towards a gradual decrease within a session. The aim of the third study was to investigate the neural basis of VRET in an acrophobic population. In particular, the study focused on measuring functional brain activity associated with both within- and between-session learning. Psychophysiological monitoring was also employed to measure levels of emotional arousal within- and between sessions. 13 acrophobic volunteers took part in three-session VRET for a fear of heights. Changes in HbO in the prefrontal cortex were measured in three blocks to investigate within–session brain activity and across three sessions to investigate between-session inhibitory learning. Results demonstrated that phobic participants have decreased activity in the DLPFC and MPFC at the beginning, however, after three sessions of VRET, activity in these brain areas increased towards normal (measured in healthy controls). Although there was no within-session learning during the first and second session, the study found a significant increase in the DLPFC at the beginning of a session. During the second block, additionally, the MPFC was activated. The magnitude of brain activity in those regions was negatively correlated with the initial level of acrophobia. Due to the technical difficulties, no significant results were found in psychophysiological measures. However, subjective fear ratings decreased significantly within- and between sessions. Moreover, participants who felt more present demonstrated stronger results in brain activity at the end of VRET. This is the first project that investigated the neural correlates of fear inhibition and inhibitory learning by combining a VR display in which people can move around and see their body, with wearable neural imaging that gave a reasonable compromise between spatial and temporal resolution. This project has an application in widening access to immersive neuroimaging across understanding, diagnosis, assessment, and treatment of, a range of mental disorders such as phobia, anxiety or post-traumatic stress disorder. An application that is receiving an interest in the clinical community is repeatable, direct and quantifiable assessment within clinics, to diagnose, steer treatment and measure treatment outcome

Within- and between-session prefrontal cortex response to virtual reality exposure therapy for acrophobia

Exposure Therapy (ET) has demonstrated its efficacy in the treatment of phobias, anxiety and Post-traumatic Stress Disorder (PTSD), however, it suffers a high drop-out rate because of too low or too high patient engagement in treatment. Virtual Reality Exposure Therapy (VRET) is comparably effective regarding symptom reduction and offers an alternative tool to facilitate engagement for avoidant participants. Neuroimaging studies have demonstrated that both ET and VRET normalize brain activity within a fear circuit. However, previous studies have employed brain imaging technology which restricts people’s movement and hides their body, surroundings and therapist from view. This is at odds with the way engagement is typically controlled. We used a novel combination of neural imaging and VR technology—Functional Near-Infrared Spectroscopy (fNIRS) and Immersive Projection Technology (IPT), to avoid these limitations. Although there are a few studies that have investigated the effect of VRET on a brain function after the treatment, the present study utilized technologies which promote ecological validity to measure brain changes after VRET treatment. Furthermore, there are no studies that have measured brain activity within VRET session. In this study brain activity within the prefrontal cortex (PFC) was measured during three consecutive exposure sessions. N = 13 acrophobic volunteers were asked to walk on a virtual plank with a 6 m drop below. Changes in oxygenated (HbO) hemoglobin concentrations in the PFC were measured in three blocks using fNIRS. Consistent with previous functional magnetic resonance imaging (fMRI) studies, the analysis showed decreased activity in the DLPFC and MPFC during first exposure. The activity increased toward normal across three sessions. The study demonstrates potential efficacy of a method for measuring within-session neural response to virtual stimuli that could be replicated within clinics and research institutes, with equipment better suited to an ET session and at fraction of the cost, when compared to fMRI. This has application in widening access to, and increasing ecological validity of, immersive neuroimaging across understanding, diagnosis, assessment and treatment of, a range of mental disorders such as phobia, anxiety and PTSD or addictions

Classical genetic algorithm for dynamic optimization of the linear model of plants production

Article presents application of classical genetic algorithm for the problem of dynamic optimization of the linear model. The model describes plants production during two years and takes into consideration plants changing. The soil in a good culture it is very important issue to obtain the highest crop. In the work the conditions for classical genetic algorithm to solving introduced problem are presented

Solution of the optimal allotment problem using classical genetic algorithm

The article presents classical genetic algorithm applied to solving optimal allotment problem. It is shown, on the base of presented example, that genetic algorithm finds optimal solution very quickly. To obtain optimal solution for a given problem with the least number of iteration, it is very important problem in numerical calculation

Application of dynamic programming for solving an optimal allotment problem

The article presents an application of dynamic programming method for solving an optimal allotment problem. On the basis of the presented example, authors showed that the dynamic programming method founded on Bellman’s equation finds an optimal solution very quickly. Finding an optimal solution of any given problem using as few iterations as possible, is a very important problem in numerical calculation. The obtained results of optimization are compared with different methods

Educational agents in distance learning environments

Agent edukacyjny jest inteligentnym i autonomicznym programem, który może być zastosowany wśrodowiskach kształcenia na odległość. Rolą agenta jest pomoc uczniom i nauczycielom w osiąganiu ich celów dydaktycznych. W artykule podano definicję oraz klasyfikację agentów edukacyjnych ze szczególnym wskazaniem na agenty pedagogiczne, których celem jest wsparcie dla zdobywania kompetencji przez uczniów. Wskazano także miejsce agentów w kompleksowych środowiskach nauczania za pośrednictwem Intemetu. W artykule omówiono niektóre znane przykłady agentów, w tym również takich, które potrafią posługiwać się językiem naturalnym w komunikacji z użytkownikiem. Agenty mogą stanowić rozwiązanie szeregu problemów, które stwarza asynchroniczna nauka przez Internet, w tym problem koncentracji uwagi oraz przedwczesnej rezygnacji z nauki.Educational agent is intelligent and autonomous software that can be integrated with distance learning environment. Its aim is to help students and teachers to reach educational goals. The definition and classification of educational agents is provided in the article, with special focus on pedagogical agents which help students during learning processes. The place of the agents in distance learning environments was described. Some known examples of the agents were shown, focusing on the ones that are able to communicate with students using natural language conversation. The educational agents are believed to be a solution to some problems occurring in asynchronous distance learning environments, i.e. lack of concentration problem or resignation before completion problem

Linear model in dynamic optimization of plants production at farm

The article presents linear model for solving dynamic optimization problem of plants production at farm. In the model the very important issue of plants changing was taken into consideration. Plants changing helps to obtain highest crop and keeps soil in good condition. Presented optimization model was applied to real data of an average farm which takes up plants production in West Pomeranian province