Electrophysiology of human action control

To respond adequately to environmental challenges it is often required to transiently suppress motor actions. This research project should investigate in which way such a flexible action control is implemented in the human brain. In particular the role of rhythmic brain activity and interregional interaction of distinct cortical areas during these functions is to be clarified. We hypothesize that a network consisting of sensorimotor and anterior cingulate cortex as well as prefrontal brain areas is involved in the initiation of motor inhibition, whereas a network including primary, premotor and motor cingulate cortex and the supplementary motor area is expected to contribute to the release of inhibition. Neural synchrony at Alpha (around 10 Hz) and Beta (13 to 20 Hz) frequency bands should be found within the above mentioned networks. There will be a focus on the exact temporal evolution of the communication within and between task-relevant networks. Electroencephalography (EEG) - non-invasive recording of electrical brain activity - will be the method used in the project. The methodological focus will be on analysis of transient phase coupling and amplitude changes within selected frequency bands. The benefit of the project should be additional knowledge about the electrophysiological basis of adaptive and flexible action control in behavior which might then be relevant for an understanding of several neurological and psychiatric disorders. In addition, the obtained results could be of relevance in the field of artificial intelligence where there might be important applications of action control.

Not only execution of motor acts is important but also their efficient, context dependent suppression. For instance, while dining in a restaurant usually a guest takes the spoon and starts eating after the waiter has put the soup on the table in front of the guest. If however, the waiter tells you that the soup is extremely hot the person has to inhibit starting to eat (execution of motor program) for a certain period of time to prevent negative aftermath. In this project it was investigated how such context dependent motor inhibition is implemented in the human brain. Results from a series of experiments suggests that rhythmical brain activity at a frequency of approximately ten periods per second (so called Alpha brain activity) is relevant for inhibition of behaviour. Rather transient cancelling of already initiated or planned movements is associated with alpha activity in a right frontal brain area, whereas rather sustained suppression of actions is reflected by high alpha waves in the motor- relevant brain areas. However, this longer lasting motor inhibition can be overcome if a change in context requires execution of a movement. This is then reflected by transient activity of a fronto-central brain network that comprises the so called anterior cingulate cortex and motor brain areas. These studies give a complete picture of how action control is implemented in the human brain. This can be of particular importance when investigating psychiatric and neurological disorders with a deficit in action control (such as Tourette Syndrome, Dystonia or Attention Deficit Hyperactivity Disorder).