Commentary: Retrieval practice protects memory against acute stress

Citation: Wolf OT and Kluge A (2017) Commentary: Retrieval practice protects memory against acute stress. A commentary on Retrieval practice protects memory against acute stress Nineteen years ago the impairing impact of stress on memory retrieval was observed in rats (de Quervain et al., 1998). Years later this effect was demonstrated in human participants (Kuhlmann et al. These non-replications may reflect a more moderate stress response and/or particularities of the learning material used in the studies (for reviews see Cadle and Zoladz, 2015; Gagnon and Wagner, 2016; Wolf, 2017). Studies in rodents revealed that this effect is caused by an interaction of a noradrenergic signal induced by the first response wave (the sympathetic nervous system) and a glucocorticoid signal induced by the second response wave (the hypothalamus-pituitary-adrenal (HPA) axis) (Roozendaal et al., 2006). The effect occurs once cortisol concentrations are elevated approx. 20–30 min after stress onset. The impairment lasts 2–3 h, which is longer than the typical stress induced cortisol elevations most likely reflecting non-genomic and genomic effects (Gagnon and Wagner, 2016; Wolf, 2017). Pharmacological studies revealed that blocking glucocorticoid secretion or blocking noradrenergic arousal with a beta blocker prevents the stress effects (de Quervain et al., 1998, 2007). In a recent paper published in Science, Smith, Floerke and Thomas tested the impact of different learning strategies on this effect (Smith et al., 2016). They used the retrieval practice strategy where participants try to retrieve the recently seen items without feedback. This strategy leads to superior memories in contrast to typical study practice (passive re-reading) approaches (Karpicke and Roediger, 2008; Roediger and Butler, 2011). On a side note it should be mentioned that studies using complex and dynamic learning material for controlling complex technical systems could, however, not observe the superiority of the testing-effect compared to additional practice (Kluge and Frank, 2014). Smith and colleagues reported that retrieval practice lead to superior memory performance. More importantly retrieval practice prevented the impairing effects of stress on memory retrieval observed in the group of participants which learned the items using the classical study practice approach. The study is thus the first to demonstrate that a rehearsal strategy might be able to create memory traces which are less sensitive to stress. Since the retrieval practice group shows an overall better memory performance it remains open whether the missing stress effects reflects better learning in the sense of " stronger memory traces in …