There is a wealth of literature that links spontaneous slow frequency oscillations with activation or approach motivational behavior that may be implicated as a driving force behind impulsivity, while alpha oscillations are involved with cessation of activity or inhibition processes (see for a review Knyazev, 2007, 2011, Knyazev et al., 2008b). Developmentally, a shift from a preponderance of spontaneous theta oscillations to alpha has been linked with the development of prefrontal inhibitory control in humans (Segalowitz et al., 2010). Consistent with this interpretation, spontaneous slow wave power (e.g., theta) has been found to be higher in children compared to adults as well as in different psychiatric conditions characterized by impulsivity, such as conduct disorder, antisocial behavior, and alcoholism compared with normal controls (Rangaswamy et al., 2003, see for review Segalowitz, Santesso, 2010). By the same token, tonic and phasic slow frequencies, such as theta power, have been interpreted to behave differently with respect to cognitive performance. Phasic theta power increases with increased cognitive performance and decreases with decreasing performance (e.g., Gevins et al., 1998). On the other hand, tonic theta is reported to increase with decreased cognitive activity and decrease with increased cognitive activity (cf. Rangaswamy, Porjesz, 2003).
