Let the voices fly away: Neurofeedback training of auditory evoked potentials in patients with auditory verbal hallucinations and healthy subjects

Rieger, Kathryn (2017). Let the voices fly away: Neurofeedback training of auditory evoked potentials in patients with auditory verbal hallucinations and healthy subjects (Unpublished). (Dissertation, Universitätsklinik für Psychiatrie und Psychotherapie, Psychotherapie Zentrum für Translationale Forschung, Medizinische Fakultät)

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Auditory verbal hallucinations are a core feature of schizophrenia. They adversely affect a patients’ social life and are accompanied by high distress. A plethora of functional and structural neurophysiological alterations associated with auditory verbal hallucinations’ occurrence have been reported, including changes within lower and higher order cortical brain areas. Two topics are of primary interest for this thesis: first, the existence of abnormal spontaneous hyperactivity in the primary auditory cortex; and second, a deficiency within the inner speech monitoring system that leads to false attributions of self-generated inner thoughts perceived as coming from an alien source. Treatment options are available for auditory verbal hallucinations, such as psychopharmacological interventions or psychotherapy, but they cannot provide adequate treatment in a significant number of cases. This thesis therefore aimed to implement EEG-neurofeedback as an additional treatment method. To apply a neurofeedback protocol, an adequate underlying neurophysiological correlate of the symptomatology must be found that can be targeted for possible treatment. One such correlate is the auditory evoked potential N100. Previous studies have shown a global reduction in the event-related potential component N100 in patients with schizophrenia. This reduction is even more apparent during the perception of auditory verbal hallucinations and is assumed to result from dysfunctional activation of the primary auditory cortex. We aimed to develop and implement event-related potential neurofeedback training in patients with hallucinations and healthy subjects. Additionally, patients were separated into a treatment group, trained with the altered N100 amplitude, and a control group trained with a presumably unaltered component, the auditory evoked potential P200. This thesis comprises two research articles reporting EEG-neurofeedback results of the developed protocol, and a meta-analysis investigating an additional possible neurofeedback training feature to treat auditory verbal hallucinations. The neurofeedback design consisted of 16 training sessions, each including one passive and two active conditions: training and transfer. Based on these conditions, neurofeedback performance was assessed using linear mixed effect modelling, which provided eight different learning parameters for either within or between sessions. The first paper presents the implementation of event-related potential neurofeedback training in a healthy population. We found significant N100 modulation in some learning parameters: immediate voluntary learning (within-session) by using mental strategies worked best. A significant learning effect assessed across a longer time period (across-session) was only found in the condition where no strategy was used (passive condition). Additionally, an unspecific habituation effect was found to lower the auditory evoked N100. The second paper aimed to expand this investigation in a patient sample, assessing two levels: 1) a neurophysiological level that investigated the ability of patients to modulate event-related potential components using the neurofeedback training protocol; and 2) a behavioural level that described the effect of neurofeedback training on hallucination-related symptoms. Unlike the healthy subjects assessed on a neurophysiological level, patients using neurofeedback training did not significantly increase the N100/P200 components. The unspecific habituation effect previously found in healthy subjects was also replicated in patients. Elaborating further on a behavioural level, we were able to identify two different learning types resulting from a correlation between the learning parameters and a subjective measure for hallucination-related symptom improvement. In Abstract 10 conclusion of Paper 2, patients predominantly showing a specific learning type seem to benefit most from EEG-neurofeedback. Finally, although this thesis focused on event-related potentials as a possible treatment feature for patients with auditory verbal hallucinations, we were also interested in other possible neurophysiological correlates associated with positive symptoms. In a meta-analysis (Paper 3), we analysed resting-state microstate abnormalities related to positive symptoms in schizophrenia and found two microstate classes, namely C and D, to be altered. This thesis concludes that the two learning types resulting from patient groups shed light on hallucination-related symptom improvements due to neurofeedback. Additional results from subjects who were able to downregulate their hallucinated voices after the neurofeedback training showed increased activity in the superior frontal gyrus along with a decreased activity in the superior temporal gyrus. This is in accordance with previous literature reporting fronto-temporal deficits relation to hallucinations. In conclusion, future treatment should target these fronto-temporal alterations.

Item Type:

Thesis (Dissertation)

Division/Institute:

04 Faculty of Medicine > University Psychiatric Services > University Hospital of Psychiatry and Psychotherapy > Translational Research Center

Graduate School:

Graduate School for Health Sciences (GHS)

UniBE Contributor:

Rieger, Kathryn and König, Thomas

Subjects:

600 Technology > 610 Medicine & health

Language:

English

Submitter:

Marlise Matti

Date Deposited:

21 Mar 2019 12:58

Last Modified:

21 Mar 2019 12:58

URI:

https://boris.unibe.ch/id/eprint/121054

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