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The Role of Phase-Amplitude Coupling in the Relationship between Acute Stress and Executive Functions

Die Rolle von Phasen-Amplituden-Kopplungen im Zusammenhang zwischen akutem Stress und exekutiven Funktionen

  • Phase-amplitude cross-frequency coupling is a mechanism thought to facilitate communication between neuronal ensembles. The mechanism could underlie the implementation of complex cognitive processes, like executive functions, in the brain. This thesis contributes to answering the question, whether phase-amplitude cross-frequency coupling - assessed via electroencephalography (EEG) - is a mechanism by which executive functioning is implemented in the brain and whether an assumed performance effect of stress on executive functioning is reflected in phase-amplitude coupling strength. A huge body of studies shows that stress can influence executive functioning, in essence having detrimental effects. In two independent studies, each being comprised of two core executive function tasks (flexibility and behavioural inhibition as well as cognitive inhibition and working memory), beta-gamma phase-amplitude coupling was robustly detected in the left and right prefrontal hemispheres. No systematic pattern of coupling strength modulation by either task demands or acute stress was detected. Beta-gamma coupling might also be present in more basic attention processes. This is the first investigation of the relationship between stress, executive functions and phase-amplitude coupling. Therefore, many aspects have not been explored yet. For example, studying phase precision instead of coupling strength as an indicator for phase-amplitude coupling modulations. Furthermore, data was analysed in source space (independent component analysis); comparability to sensor space has still to be determined. These as well as other aspects should be investigated, due to the promising finding of very robust and strong beta-gamma coupling for all executive functions. Additionally, this thesis tested the performance of two widely used phase-amplitude coupling measures (mean vector length and modulation index). Both measures are specific and sensitive to coupling strength and coupling width. The simulation study also drew attention to several confounding factors, which influence phase-amplitude coupling measures (e. g. data length, multimodality).
  • Sind exekutive Funktionen über Frequenzbandkopplungen im Gehirn implementiert und spiegelt sich ein vermuteter Verhaltenseffekt von Stress auf exekutive Funktionen in Frequenzbandkopplungen wieder? Diese Frage wurde in zwei elektrophysiologischen Experimenten untersucht. Es zeigte sich eine konsistente und robuste Frequenzbandkopplung zwischen Beta und Gamma. Die Ergebnisse indizieren, dass eine weitere Untersuchung der funktionellen Bedeutsamkeit dieser Frequenzbandkopplung für exekutive Funktionen und Stress sinnvoll ist. Zudem weist die Arbeit Validität und Reliabilität zweier gängiger Kopplungsmaße nach.

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Author:Mareike Hülsemann
Advisor:Ewald Naumann
Document Type:Doctoral Thesis
Date of completion:2017/03/08
Publishing institution:Universität Trier
Granting institution:Universität Trier, Fachbereich 1
Date of final exam:2016/12/15
Release Date:2017/03/08
Tag:Cortisol; Frequenzbandkopplungen; Phasen-Amplituden-Kopplung
cross-frequency coupling; mean vector length; modulation index; phase-amplitude coupling; simulation study
GND Keyword:Arbeitsgedächtnis; Elektroencephalogramm; Exekutive Funktionen; Flexibilität; Inhibition; Stress
Institutes:Fachbereich 1 / Psychologie
Dewey Decimal Classification:1 Philosophie und Psychologie / 15 Psychologie / 150 Psychologie

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