Topic: endogenous fluctuations

Brain rhythms in the alpha frequency range [8Hz-12Hz] are present in idling conditions and sleep. They have also an important role in cognition, e.g. they modulate activity of task-irrelevant neural populations, and enhances selective attention among others. A prominent occipital alpha wave emerges in mammals when the subjects close eyes (alpha generation) and it is blocked when opening eyes (alpha blocking). This switch in alpha power is accompanied by an inverse switch in gamma activity [1]. With open eyes, the brain receives strong input from the external world and responds by strong gamma-