By Lucilla De Arcangelis (Caserta, Italy).
Recent evidence suggests that the alpha rhythm plays an active role in information processing, modulating behavioral and cognitive performance. However, the functional link between alpha activity and architecture of neuronal dynamics remains poorly understood. To address this question, here we study collective neural activity during resting wake and NREM sleep, a physiologic state with marginal presence of alpha rhythm. We show that, during resting wake, alpha oscillations drive alternation of attenuation and amplification bouts in neural activity. Our analysis indicates that inhibition is activated in pulses that act on avalanches within an alpha cycle and gradually suppress neural activity, while excitation is successively enhanced over the timescales of a few alpha cycles to amplify neural activity. Furthermore, we show that long-term, periodic fluctuations in alpha amplitude, known as the ”waxing and waning” phenomenon, are associated with an attenuation-amplification mechanism acting over the timescales of several seconds and described by a power law decay of the activity rate in the “waning” phase. Importantly, we do not observe such dynamics during NREM sleep. These findings suggest that the alpha rhythm functions as a “pacemaker” for the rhythmic alternation of inhibition and excitation bouts across multiple timescales, the “waxing and waning” being a long-term control mechanism of cortical excitability.