Alina Studenova | Unifying evoked responses and oscillatory neuronal dynamics

What we know about the functioning of the human brain is to a very large extent based on non-invasive electrophysiological recordings such as electro-and magnetoencephalography (EEG/MEG). With these techniques, one can obtain two main types of neuronal activity: evoked responses and oscillations. Evoked responses are events that occur in the brain as a reaction to a sensory stimulus or as preparation for a movement, i.e., they are transient time- and phase-locked responses to stimuli. Oscillations are ongoing, spontaneous rhythmic waves, meaning they occur with or without stimulus. Evoked responses and oscillations are often considered distinct types of activity. However, we suggest that some evoked responses and some oscillations should not be regarded as different neuronal phenomena but rather can be viewed as one and the same process. The unifying principle is the baseline-shift mechanism, which is based on two prerequisites: 1) the amplitude of oscillations changes after the stimulus onset; and 2) oscillations are asymmetric around zero. If prerequisites are met, then an evoked response is generated due to oscillatory dynamics. In the talk, I will share the results of our three studies investigating which evoked responses and oscillations may comply with the baseline-shift mechanism. By revealing a mechanistic connection between evoked responses and oscillations, we provide an integrative outlook on neuronal signals.