Interacting with brain oscillations to change perception
Brain oscillations reflect interactions between neuronal elements which functionally assemble through synchronization in specific frequency bands, depending on the state of the brain and on the task that is currently being executed. This gives rise to brain rhythms that can be measured on the scalp by electroencephalography (EEG). Transcranial magnetic stimulation (TMS) can be used to stimulate cortical areas in rhythmic pulse-trains, at frequencies that characterize EEG-signals. This raises two intriguing questions: Could frequency-tuned TMS be used to transiently entrain brain oscillations, and would this result in behavioural consequences? My talk covers (1) EEG-signatures that carry information on the excitability of visual cortex (amenable to attention control) and predict perception of an upcoming visual event. It then addresses the questions whether (2) these signatures can be transiently entrained by frequency-tuned rhythmic TMS, and whether (3) this alters perception in expected directions, i.e. in line with the proposed functional roles of these oscillations. The results provide information on the role of brain oscillations in perception and attention, and reveal new mechanisms of TMS actions.