Therefore, our study combines daily process ratings and their concurrent complexity analyses with repeated high-field functional MRI scans. The main scientific question is whether order transitions within the psychotherapeutic process correspond to changes in neuronal activation patterns. This study demonstrates that psychotherapy efficiently works in treating obsessive-compulsive disorders. The changes mainly affect the anterior and medial cingulate cortex/supplementary motor area, the left and right dorsolateral prefrontal cortex, and the right insular cortex. Our findings corresponds with those of other studies, which essentially showed that both, pathological hyper- or hypofunction of neuronal networks involved in compulsion-specific behaviors normalize in the course of therapy. Actual psychological change TWS119 processes were documented via daily self-assessment with the Therapy Process Questionnaire. The self-rating data were related to changes in neuronal activation patterns and demonstrate that the most concise changes in brain activity occur in temporal proximity of order transitions. In synergetics and complexity science, order or phase transitions indicate the spontaneous emergence of new collective patterns or qualitative shifts of such patterns in complex, nonlinear systems. Although we identified only one order transition in most of the cases, we do not suggest that psychotherapy consists in a simple transition from a pathological state to a physiological or healthy state. It can be assumed that there are several stable regimes characterizing healthy functioning and even more than one pathological state. Psychotherapy does not only trigger movements of patient��s behavior in a multi-attractor landscape but gives rise to emerging new attractors in a potential landscape of increasing complexity. A higher scan frequency during the change process could provide more detailed insight into cascades of such order transitions. Changes in the activity of brain areas outside of order transitions are considerably lower than changes during order transitions, similar to the differences between fMRI scans from healthy controls, who did not undergo psychotherapy and did not experience any dynamic order transitions. Results support the assumption that psychotherapeutic processes occur in the form of discontinuous changes, as postulated by the theory of complex, self-organizing systems. According to this model, psychotherapy is the procedural creation of conditions enabling biopsychosocial self-organization processes. The strong relationship between order transitions and BOLD responses observed in the present study reversely proves the operationalization of order transitions through the maximum of dynamic complexities of the time series, as gained from daily self-assessment by using the Synergetic Navigation System. From 20 inter-scan-intervals during psychotherapy, 11 were identified as order transitions, 7 of which occurred between the first and the second fMRI measurement. This corresponds to findings of so-called early rapid responses, which demonstrate that changes in Axitinib symptom and problem intensity occur discontinuously and mainly during early phases of the psychotherapeutic process. Surprisingly, these changes frequently occur before main interventions are applied, for example, cognitive restructuring before the implementation of specific methods from cognitive behavior therapy. Stiles et al. found sudden improvements among clients with a variety of disorders treated by a variety of approaches in routine clinical settings; Stulz et al. report on early changes in routine outpatient conditions. As demonstrated by a single case report on the psychotherapy process of an OCD patient, the steepest gradient of symptom reduction and a qualitatively different brain activity pattern occurred before main interventions, were implemented.