Practice question

Alpha rhythm consists of regular 8-13 Hz oscillations most prominent over occipito-parietal cortex when a person is awake but resting quietly with eyes closed, minimizing visual input and mental effort. The rhythm arises from synchronized thalamocortical feedback loops in an idling yet alert cortex, suppressed by eye opening, mental arithmetic, attention or anxiety. Excited states replace alpha with low-amplitude fast beta activity, deep sleep produces high-amplitude slow delta, drowsiness shows theta, and focal damage causes pathological slowing. Thus alpha signifies relaxed wakefulness, not sleep or excitation.