Functional Aspects of the Minimal Self – the Case of Schizophrenia

The overall goal of this project is to provide a thorough and fine- grained characterization of disturbances of the minimal self in patients suffering from schizophrenia. Furthermore, the data from experiments in patients and healthy controls will be used to model their behavior in a neurocomputational model with the ultimate aim to extract general principles of the construction of an active self. Schizophrenia represents a severe mental disorder, in which self-disturbances are reported as a disintegration of subjectivity (often termed ‘self- disorders’, SD). Patients report a long-time persisting feeling of self- transformation, bodily self-alienation, and permeability of ego- boundaries. Symptoms include disturbed stream of consciousness, self-awareness, corporeality, demarcation, and existential reorientation, all of which are interrelated. They can be assessed in great detail using the “Examination of Anomalous Self-Experience” (EASE) instrument (Parnas et al., 2005), a semi-structured clinical interview focusing on the experiential and phenomenological anomalies of schizophrenia spectrum disorders. From a computational perspective, disturbances of the self in schizophrenia such as disturbed sense of agency (SoA) or sense of ownership (SoO) are described in terms of deficits in predicting sensory consequences, which may account for several aspects of SD. In our project, we will assess the dimensions of self-disturbance in terms of neurocognitive mechanisms linked to the subdomains of the EASE. Combining neuro-computational modelling with data from behavioral experiments and electrophysiological recordings, we will continue to carry out and extend the experimental tasks, which have been previously established by our collaborators and us within the DFG SPP “active self” in patients with schizophrenia (ICD-10: F20.0) and healthy controls. In interdisciplinary collaborations for the second funding period, we will use experimental data on impaired SoA and SoO in schizophrenia to inform the development of anatomically plausible computational models as well as a humanoid robot and focus on altered prediction of sensory input. The implementation of a disturbed sense of self resembling the symptoms of schizophrenia within a neurocomputational model and a humanoid robot is a worldwide unique approach. This “lesion model” of self-disturbances will broaden our understanding of mechanisms underlying the development of a self. Ultimately, our results will advance the understanding of schizophrenia as a disorder of the basic sense of self and promote the development of new therapies focusing on the reconstitution of the active self.

Dr. Laura Kaltwasser, Dr. Martin Voss, Prof. Dr. Fred Hamker