Inhibitory control, or the ability to suppress unwanted thoughts or behaviour, is essential in everyday life, yet often underappreciated. The critical importance of inhibition becomes clear when the process fails, as in attention deficit hyperactivity disorder (ADHD) and Tourette’s syndrome where there is too little inhibition, or as in Parkinson’s disease where there is too much, resulting in slowness of movement (bradykinesia) and rigidity. Over the past decade, lesion studies, single cell recordings and neuroimaging research have identified a fronto-subthalamic network mediating behavioural inhibition. The power (i.e. amplitude) of oscillations in the beta band (15-30Hz) within these regions has been linked to successful inhibition. However, very little is known about how beta oscillations facilitate communication between the different cortical and subcortical areas. This not only limits our mechanistic understanding of the brain’s inhibitory control system, it also hampers the development of more effective treatment strategies for neurological and psychiatric patients suffering from inhibitory control deficits.
The overarching aim of this proposal was to identify oscillatory signatures that are causally relevant for inhibitory control, and to develop an innovative neuromodulatory approach to restore normal inhibitory control. Specifically, we made use of novel transcranial alternating current stimulation (tACS) approaches, capable of dynamically synchronising or desynchronising oscillatory activity, to (1) Investigate the causal role of beta oscillatory phase (WP1), and cross-frequency coupling between the beta and gamma frequencies (WP2). (2) Develop a proof of concept for a non-invasive adaptive stimulation approach to ameliorate abnormal neural communication (WP3).
