Frontal midline theta observed in humans during attention-related tasks is integral to understanding brain functioning during information processing. In one study, researchers examined event-related EEG changes during the performance of mental calculations in alcoholics and control subjects. The study was based on the hypothesis that performance deficits would be indicated by reduced frontal theta power in alcoholic patients. Researchers recorded EEGs in adult alcoholics and normal volunteers during the performance of a simple addition problem (active theta) and during a resting interval (resting theta). The difference between resting and active theta power is a measure of processing capacity—the lower the resting theta power and the higher the active theta power, the more efficient the brain processing (Klimesch et al. 2001). The difference in theta power between resting and problem-solving conditions was significantly lower in alcoholics compared with control subjects at the anterior frontal electrodes. Alcoholics manifested increased resting theta and decreased active theta, indicating decreased and inefficient processing capacity. These deficits in performance, indexed by low evoked (active) theta power during mental effort, reflect frontal lobe dysfunction in alcoholics (Suresh et al. submitted [a]). These deficits involve inhibitory processes and are manifested as impairments in working memory and sustained attention.
