EEG-based neurofeedback in schizophrenia: Normalization of frontal-midline theta

Typical consequences in schizophrenia are work absence and early retirement. Such poor every day activities are associated with executive dysfunctioning. Under healthy conditions, successful executive functioning is associated to increased frontal-midline theta oscillations. Such event-related modulations are related to enhanced coupling between neuronal spikes and the phase of the population theta cycle. Crucially, fm-theta has been shown to be reduced in schizophrenic patients compared to healthy subjects and seems to underlie impaired executive functioning. From a rehabilitation perspective, the question arises if disturbed oscillations can be directly targeted with neuroscientific approaches in order to influence associated disturbed cognition in schizophrenia. In this regard EEG-neurofeedback represents a putative intervention to self-regulate oscillations. However, it is debated if this patient group can self-regulate their own oscillations at all. The current study aims first at exploring the specific fm-theta disturbances of schizophrenic patients in memory updating using a two-back experimental paradigm and comparing the results with healthy, matched subjects. Ultimately, the study tests a personalized five training session fm-theta neurofeedback with schizophrenic patients including an active control group. The study included 29 patients diagnosed as schizophrenic (F20, ICD-10) and 16 healthy control subjects. 16 patients were pseudo-randomized to either the experimental or active control group (the so-called pseudo group) for neurofeedback. With regard to the two-back task, reduced performance of schizophrenic patients was accompanied by a total loss of fm theta modulability. This was reflected by two deficits with respect to task-relevant stimuli and working memory load in the two-back task. With respect to the theta neurofeedback training, two main results were observed. First, patients in the experimental group showed indeed increased theta amplitudes over the course of the training compared to the pseudo group. And second, this increase transferred to one of the fm-theta modulation deficits in the n-back task, but (yet) did not lead to increased performance. Nevertheless, our data suggest that a non-invasive, low-cost EEG-neurofeedback training may represent a therapeutic tool also in psychiatric patients.