Veränderte kortikale Plastizität und Konnektivität bei psychisch nicht erkrankten erstgradigen Angehörigen von Patienten mit einer Schizophrenie

Altered cortical plasticity and connectivity in unaffected first-degree relatives of patients with schizophrenia

by Kristina Misewitsch
Doctoral thesis
Date of Examination:2019-08-08
Date of issue:2019-07-31
Advisor:Prof. Dr. Thomas Wobrock
Referee:Prof. Dr. Andrea Antal
Referee:Prof. Dr. Thomas Meyer
Persistent Address: http://dx.doi.org/10.53846/goediss-7584

 

 

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Abstract

English

Content: Impaired cortical plasticity and brain dysconnectivity are discussed to be essential pathomechanisms of schizophrenia. NMDA receptors, glutamate and intracellular calcium concentration play a key role in this regard. The aim of the present study was to investigate differences in motor-cortical plasticity and interhemisphreic connectivity in unaffected first-degree relatives compared to schizophrenia patients and healthy subjects using cathodal transcranial direct current stimulation (tDCS) and TMS. Methods: To induce LTD-like plasticity the left primary motor cortex was stimulated by cathodal tDCS. Cortical excitability was determined by transcranial magnet stimulation (MEP amplitudes) before and after cathodal stimulation over the motor cortices of both hemispheres. Furthermore, the cortical silent periot and resting motor thresholds were measured before and after tDCS Results: Relatives and patients showed impaired motorcortical LTD-like plasticity responses over the stimulated hemisphere compared to the healthy control group. On the non-stimulated hemisphere, patients with schizophrenia exhibited reduced LTD-like plasticity, while in first-degree relatives reversed LTD-like plasticity was observed. Conclusions: The findings provide experimental evidence for the influence of genetic risk on LTD-like cortical plasticity and the associated interhemispheric connectivity following cathodal tDCS. The familial predisposition changes and inverts the cortical plasticity of unaffected relatives. An imbalance of glutamatergic and dopaminergic transmission can be discussed in addition to deficits of GABAergic neurotransmission possible pathomechanisms.
Keywords: schizophrenia; plasticity; TMS; connectivity; tDCS
Schlagwörter: Schizophrenie; Plastizität; TMS; tDCS; Gleichstromstimulation; Konnektivität
 
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