Across time and space: spatial-temporal binding under stress

Successful episodic memory requires binding of event details across spatial and temporal gaps. The neural processes underlying mnemonic binding, however, are not fully understood. Moreover, although acute stress is known to modulate memory, if and how stress changes mnemonic integration across time and space is unknown. To elucidate these issues, we exposed participants to a stressor or a control manipulation shortly before they completed, while electroencephalography was recorded, an encoding task that systematically varied the demands for spatial and temporal integration. Associative memory was tested 24 h later. While early event-related potentials, including the P300 and Late Positive Component, distinguished different levels of spatiotemporal discontinuity, only later Slow Waves were linked to subsequent remembering. Furthermore, theta oscillations were specifically associated with successful mnemonic binding. Although acute stress per se left mnemonic integration largely unaffected, autonomic activity facilitated object memory and glucocorticoids enhanced detail memory, indicative for mnemonic integration. At the neural level, stress amplified the effects of spatiotemporal discontinuity on early information processing. Together, our results indicate that temporal and spatial gaps recruit early neural processes, providing attentional resources. The actual binding success, however, appears to depend on later processes as well as theta power and may be shaped by major stress response systems.