Influencing social-emotional actions The effect of theta-gamma coupled tACS on social-emotional actions and aPFC-M1 functional connectivity

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2019-08-01
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en
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In our everyday life we are used to regulating our social-emotional behaviour, for example, when you want to approach a fellow researcher at a conference for a possible collaboration. An important brain region involved in the implementation of social-emotional control is the anterior prefrontal cortex (aPFC). Previous research found that control over social-emotional behaviour is implemented by thetaband oscillations in the aPFC that are phase-locked to the power increase of gamma band oscillations in the motor cortex. In this project we studied the effects of non-invasive brain stimulation on socialemotional behaviour using transcranial alternating current stimulation (tACS). We aimed to investigate (1) whether we can influence social-emotional actions by applying different types of theta-gamma coupled tACS and (2) how the functional connectivity patterns of the brain change as a consequence of the different stimulation conditions. In our tACS/fMRI study, 44 healthy participants performed the approach-avoidance task while receiving tACS stimulation (in-phase, anti-phase or sham) in the MR scanner. During the task, the participant used a joystick to either approach happy faces and avoid angry faces (affect-congruent condition) or avoid happy faces and approach angry faces (affect-incongruent condition). Error rates and reaction times were measured during the task, together with ongoing brain activity. We found reduced congruency effects for error rates but not for reaction times in-phase stimulation as compared to anti-phase stimulation. Moreover, a stronger functional connectivity was found between aPFC (or lateral frontal pole) and M1 for in-phase compared to anti-phase stimulation. These findings show improvement in social-emotional control when theta-band oscillations of the aPFC are phase-coupled to the power increases of the gamma band oscillations of the M1. This research has high clinical relevance as the findings suggest that theta-gamma coupled tACS could ultimately be used to develop possible new treatments for social, emotional and behavioural disorders, such as social anxiety.
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Faculteit der Sociale Wetenschappen