Whereas alpha activity is largely characteristic of the organism at rest, beta activity is associated with active mental states related to emotional or cognitive processing and even anxious arousal (Ray & Cole, 1985). Early preclinical research found that increased beta activity was observed in cats in hunting situations, which was interpreted as reflecting a state of expectancy and inhibition of movement (Steriade et al., 1990). More recent research with humans has corroborated the role of ‘sensorimotor’ beta activity in motor inhibition by demonstrating that initiating movement is robustly accompanied by decreases in beta power (Engel & Fries, 2010). Benzodiazepines, which bind specifically to GABA receptors (Tallman & Gallager, 1985), produce increases in beta power (Domino, French, Pohorecki, Galus, & Pandit, 1989), which has been interpreted as evidence for a role of GABA in the production of beta activity. This hypothesis is supported by findings from empirical work and computational modeling approaches (Muthukumaraswamy, Edden, Jones, Swettenham, & Singh, 2009; Whittington, Traub, Kopell, Ermentrout, & Buhl, 2000).
