Several lines of evidence suggest that asymmetric anterior brain activation is related to affective style, linking left hemisphere activation to positive affect and right hemisphere activation to negative affect. However, previous reports of left frontal hypoactivation in depressed patients were not confirmed in recent studies. This study evaluated additional characteristics of resting EEG alpha (8–13 Hz) asymmetry in 15 clinically depressed patients and 22 healthy adults by recording EEG activity on two separate occasions, 2–4 weeks apart. Across both sessions, group differences in anterior EEG asymmetry were compatible with the original hypothesis. However, groups differed in temporal stability of anterior EEG asymmetry, which was retest reliable in controls but not depressed patients. In contrast, temporal stability of posterior EEG asymmetry was acceptable in both groups. Increased variability of anterior EEG asymmetry may be a characteristic feature for depression, and, if so, this would challenge the notion that anterior EEG alpha asymmetry is a trait marker for depression.

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Cognitive control involves adjustments in behavior to conflicting information, develops throughout childhood and declines in aging. Accordingly, developmental and age-related changes in cognitive control and response-conflict detection were assessed in a response-compatibility task. We recorded performance measures, pre-RT activity and medial frontal negativity (MFN), sequentially-occurring, putative ERP indices, respectively, of cognitive control and response-conflict detection. When response conflict reached the highest levels by requiring incompatible responses on post-error trials, children and older adults showed the greatest performance decrements. ERPs indicated that young adults implemented control (pre-RT) and detected the increased conflict (MFN) only when that conflict was at the highest levels, whereas children and older adults did so at lower levels (e.g., post-error, compatible responses). Consequently, the developmental and age-related performance decrements observed here may be due to the undifferentiated and inefficient manner in which children and older adults recruited the processes associated with cognitive-control and response-conflict detection.

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