Working memory-related frontal theta activity is decreased under acute stress

Acute stress impairs prefrontal cortex (PFC) function and has detrimental effects on working memory (WM) performance. Converging evidence from electrophysiological studies suggests a close link between WM processes and frontal theta (FT) activity (4-8 Hz). However, the effect of stress on WM-related FT activity has not been investigated yet. To shed light on this topic we acquired EEG data from 31 healthy male subjects who underwent a stressful and a neutral control condition. In both conditions, they performed an n-back WM task at two different difficulty levels. Our results showed that WM-related FT activity was decreased under stress. Behaviorally, we found performance impairments under stress in the difficult task condition that were related to FT decreases. Increased cortisol levels indicated a successful moderate stress induction. These findings indicate that FT is a potential neurobiological marker for intact PFC functioning during WM and further supports the recently made assumption that FT acts in the PFC to optimize performance.