Where language meets action: The neural underpinnings of gesture performance in schizophrenia

Viher, Petra (2018). Where language meets action: The neural underpinnings of gesture performance in schizophrenia (Unpublished). (Dissertation)

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Gestures are an integral part of social interactions, since they are crucially involved in nonverbal and verbal communication. They convey language that is expressed as motor action. Thus, successful gesturing depends on intact language and motor functions. Patients with schizophrenia show abnormalities in motor behavior, language, and consequently also in gesturing. Since gesture impairments predict poor course and outcome in schizophrenia, they may operate as an important treatment target. However, only little is known about the neural underpinnings of gesture performance in schizophrenia. This constitutes a highly promising approach, as schizophrenia is characterized by structural and functional brain abnormalities thought to contribute to its symptoms and aberrant behavior. A more profound understanding of disturbed gesture performance in schizophrenia can hence be gained by studying the neural underpinnings of motor behavior, language, and their interface gestures.
Therefore, we aimed to investigate the structural correlates of impaired gesture performance in schizophrenia. Five studies were conducted to reach this aim. In a first step, we examined the neural underpinnings of both, the motor and the language dimension, which build the basis for successful gesturing. As brain dysconnectivity is a hallmark of schizophrenia, white matter (WM) correlates of the symptom dimensions might be particularly promising in explaining brain-behavior associations. Thus, in our first study, we explored the relationship between WM microstructure and the symptom dimensions of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), with a special focus on the motor and language dimension. Our second study was conducted to gain more insights into the WM correlates of the disorganized speech dimension, since we assumed that a distinction of formal thought disorder (FTD) into a positive and negative pole might be crucial to identify biological correlates. Thus, we used a different rating scale compared to the DSM-5, namely the Bern Psychopathology Scale, which takes into account this differentiation of positive and negative FTD. In our third study, we shifted from WM to another marker of dysconnectivity and elaborated resting state functional connectivity within the motor system in patients with schizophrenia and its associations with disturbed motor behavior.
In a second step, we examined the structural correlates of impaired gesture performance in schizophrenia. In our fourth study, we were interested whether possible cortical thickness alterations of regions within the praxis network are related to gesture production and recognition in schizophrenia. Finally, the aim of the fifth study was to explore the WM organization of the praxis network and how it might predict gesture production in a sample including both, patients with schizophrenia and healthy subjects. Thus, this study aimed to provide novel insights into the structural connectivity of the praxis network in general, whereby schizophrenia served as an ideal model displaying gesture deficits and WM abnormalities.
Our findings revealed several associations of brain alterations with symptoms and aberrant behavior in patients with schizophrenia. The first three studies indicated that aberrant motor behavior and disorganized speech were related to specific brain alteration patterns. While disorganized speech was related to WM abnormalities in a predominantly fronto-temporal language network, aberrant motor behavior was linked to WM alterations of the motor tract and functional hyperconnectivity within the motor system. Moreover, the last two studies revealed a link between disturbed gesture performance with cortical thinning and reduced connectivity of the praxis network. More precisely, the fourth study
detected cortical thinning in various areas of the praxis network in patients with gesture deficits, and an association of gesture recognition and cortical thinning in all patients. The fifth study revealed that gesture production in healthy subjects and patients with schizophrenia is predicted by global and local efficiency and by specific connections of the praxis network. Therefore, the findings of our last study contribute to a more comprehensive understanding about the neural correlates of gesture production in general.
The focus of our studies was on gestures forming the interface of the motor and language dimension. Our results revealed several brain-behavior associations and support the view that schizophrenia symptoms derive from aberrant brain structure and function. Most importantly, we observed an association of impaired gesturing with structural alterations of the praxis network. This enhanced understanding of the neural basis of gesture deficits is of great importance for the comprehension of social dysfunction in schizophrenia and might further encourage researchers to develop novel interventions to improve the quality of life and functional outcome in patients with schizophrenia. In addition to pharmacological treatment, which affects social functioning rather via an indirect route, future studies could develop and apply social-cognitive trainings or non-invasive brain stimulation techniques that might directly target gesture performance in schizophrenia.

Item Type:	Thesis (Dissertation)
Division/Institute:	04 Faculty of Medicine > University Psychiatric Services > University Hospital of Psychiatry and Psychotherapy > Translational Research Center 04 Faculty of Medicine > University Psychiatric Services > University Hospital of Psychiatry and Psychotherapy 04 Faculty of Medicine > University Psychiatric Services
Graduate School:	Graduate School for Health Sciences (GHS)
UniBE Contributor:	Viher, Petra, Walther, Sebastian
Subjects:	600 Technology > 610 Medicine & health
Language:	English
Submitter:	Petra Viher
Date Deposited:	30 Jan 2019 07:48
Last Modified:	05 Dec 2022 15:21
URI:	https://boris.unibe.ch/id/eprint/121815