Contributions to Neuropsychotherapy of the Combined Use of Neuroimaging and Virtual Exposure for Assessment in Psychological Treatments.

Abstract Neuropsychotherapy is a new philosophy in the treatment of mental disorders that bases its principles in the application of the information we have about the brain activations and brain functioning to adjust the therapy to them, in order to center the process in how the brain evolves to its normal activations. New tools in the field of neuroimaging have helped in this process, providing accurate and detailed information about how the particular brain of each patient works. Between the many neuroimaging techniques available nowadays, the functional magnetic resonance (fMRI) stands out by its high spatial resolution, which allows a better knowledge of which brain area is activated before each stimulus or while performing each activity. The disadvantages this technique presents in terms of size of the scanner and restriction of movements give light to another technique, more suitable in certain domains: the electroencephalography (EEG), which provides a greater freedom of movement and higher temporal resolution. For the purposes of this PhD Thesis, both techniques will be compared, in order to find which one better suits our interests. For doing so, another factor will be taken into account. Due to the limitations the neuroimaging techniques have in terms of presentation of the stimuli, we are not able to expose the subject to certain kinds of real life situations. There is where the virtual reality (VR) enters the scene. With VR we are able to move the subject to a virtual world where any kind of stimulus is possible. In the case of neuropsychotherapy, it will allow the exposition of the patient to a situation related to his disorder, in a safer and more controlled environment. In fact, virtual reality has been widely used for the treatment of psychological disorders; but, until now, it has not been applied during the assessment of the disease. For the aims of this Thesis, virtual environments will be used for the assessment of subjects before and after undergoing a psychological treatment for a specific disorder, using neuroimaging techniques to find useful information that could help during the therapeutic process. As an example of disorder, the phobia to small animals (spiders and cockroaches) has been chosen, although the conclusions of this study could be extended to other kinds of psychological disorders. Before being able to assure that the brain activations obtained are related to the disorder and not to other issues, it is needed to measure the sense of presence the subjects felt during the virtual experience. This is why before the assessment of a psychological disorder, a study of the sense of presence in a virtual environment was introduced. This study also helped in the decision of which neuroimaging technique apply in the second part of the Thesis. EEG and fMRI were used for the measure of presence in the same virtual environments, and the results in terms of brain activations were compared. Presence was also measured by means of questionnaires, the traditional subjective way of measuring it. As a result of this study it is expected to check if VR could effectively stimulate presence and which neuroimaging technique is more appropriate for the targets of this Thesis. To sum up, the initial hypotheses of this Thesis are that: 1- The new neuroimaging techniques can provide of useful information to use during neuropsychotherapy. 2- Virtual reality would help in the assessment of the disorder, improving the accuracy in the way the subjects are exposed to the stimuli. 3- The environments used would be immersive enough so the patient will feel present in them and feel them as real. For fulfilling these objectives, each of the two courses of work (study of presence and assessment of a mental disorder) was divided in two parts. In total, four studies were developed: 1- Study of the sense of presence in a virtual environment using fMRI: the aim of this part of the Thesis was to check if the environments were able to stimulate the sense of presence, correlating the results with those given to questionnaires. 2- Study of the sense of presence in a virtual environment using EEG: the aim here was to compare the brain activations obtained with EEG with those from the previous study, and if the responses of the questionnaires were equivalent despite being in a less intrusive scanner. As a result of these two studies, it was decided that the environments were immersive enough to induce the sense of presence, and that the best neuroimaging technique for the next part of the Thesis was the fMRI, due to the higher spatial resolution it brought. 3- Assessment of a psychological disorder, pre-treatment: once decided the study will continue with fMRI, the areas related to a specific disorder (small animals? phobia) were studied using VR as stimulus. Until now, the assessment has been done using real animals as stimuli but not using VR, which here is hypothesized to allow a better approach to the phobic experience than the view of photographs or videos of real animals. 4- Assessment of the state of subjects with a psychological disorder, post-treatment: once the patients had underwent a treatment to cure the disorder, they were assessed again to check if the brain areas related to the phobia stopped being activated after it. As a result of this second part of the Thesis, the brain areas related to the phobia (that stopped being activated after the treatment) were obtained, and this information is hoped to be useful in future neuropsychotherapeutic works, for the better adjustment of the disorder. In conclusion, this PhD Thesis studies the advantages that the new neuroimaging techniques and virtual reality could bring to the study of neuropsychotherapy.