Beyond pulsed inhibition: Alpha oscillations modulate attenuation and amplification of neural activity in the awake resting-state

Alpha oscillations are a distinctive feature of the awake resting state of the human brain. However, their functional role in resting-state neuronal dynamics remains poorly understood. Here we show that, during resting wakefulness, alpha oscillations drive an alternation of attenuation and amplification bouts in neural activity. Our analysis indicates that inhibition is activated in pulses that last for a single alpha cycle and gradually suppress neural activity,while excitation is successively enhancedover a fewalpha cycles toamplify neural activity. Furthermore, we show that long-termalpha amplitude fluctuations—the ‘‘waxing and waning’’ phenomenon—are an attenuation-amplificationmechanismdescribed by a power-lawdecay of the activity rate in the ‘‘waning’’ phase. Importantly, we do not observe such dynamics during non-rapid eyemovement (NREM) sleep with marginal alpha oscillations. The results suggest that alpha oscillations modulate neural activity not only through pulses of inhibition (pulsed inhibition hypothesis) but also by timely enhancement of excitation (or disinhibition).