Psychological Stress Improves Hippocampal-Dependent Memory

Psychological Stress Improves Hippocampal-Dependent Memory

A large and growing body of research shows that acute stress improves memory performance while chronic stress impairs memory performance. However, the majority of the work in this area has relied on testing various correlates of memory performance after acute or chronic stress protocols in rodents. A particularly robust finding is that acute exposure to a stressor enhances hippocampal-dependent memory performance in the Morris Water Maze test of spatial navigation in rodents. Importantly though, the extent to which acute stress can improve hippocampal-dependent memory in humans remains unclear. One previous study using a Virtual Morris Water Maze (VMWM) test demonstrated that acute exposure to physical (cold) stress also improves hippocampal-dependent memory performance in humans. However, given that humans typically suffer from psychological (as opposed to physical) stress, the role of ethologically relevant (i.e. psychological) stress in human memory performance remains undetermined. We predicted that acute psychological stress in humans will also result in an improvement in hippocampal-dependent memory performance in the V M WM test. To that end, we employed a validated protocol for inducing psychological stress in humans, the Trier Social Stress Test (TSST) along with a placebo version of this protocol. Additional dependent measures included heart rate, biochemical correlates of stress (cortisol and alpha-amylase) as well as neuropsychological assessments of stress and anxiety. As predicted, and consistent with previous findings, preliminary analyses show that compared to participants in the placebo group, participants who experienced social stress (TSST) performed better on the VMWM test of spatial navigation.