Recent studies suggest brain oscillations as a mechanism for cerebral integration. Such integration can exist across a number of functional domains, with different frequency rhythms associated with each domain. Here, evidence is summarized which shows that delta oscillations depend on activity of motivational systems and participate in salience detection. Theta oscillations are involved in memory and emotional regulation. Alpha oscillations participate in inhibitory processes which contribute to a variety of cognitive operations such as attention and memory. The importance of inhibitory functions associated with alpha oscillations increases during the course of evolution. In ontogenesis, these functions develop later and may be more sensitive to a variety of detrimental environmental influences. In a number of developmental stages and pathological conditions, a deficient alpha and/or increased slow-wave activity are associated with cognitive deficits and a lack of inhibitory control. It is shown that slow-wave and alpha oscillations are reciprocally related to each other. This reciprocal relationship may reflect an inhibitory control over motivational and emotional drives which is implemented by the prefrontal cortex.