Dynamically changing effects of corticosteroids on human hippocampal and prefrontal processing

Abstract

Stress has a powerful impact on memory. Corticosteroids, released in response to stress, are thought to mediate, at least in part, these effects by affecting neuronal plasticity in brain regions involved in memory formation, including the hippocampus and prefrontal cortex. Animal studies have delineated aspects of the underlying physiological mechanisms, revealing rapid, nongenomic effects facilitating synaptic plasticity, followed several hours later by a gene-mediated suppression of this plasticity. Here, we tested the hypothesis that corticosteroids would also rapidly upregulate and slowly downregulate brain regions critical for episodic memory formation in humans. To target rapid and slow effects of corticosteroids on neural processing associated with memory formation, we investigated 18 young, healthy men who received 20 mg hydrocortisone either 30 or 180 min before a memory encoding task in a double-blind, placebo-controlled, counter-balanced, crossover design. We used functional MRI to measure neural responses during these memory encoding sessions, which were separated by a month. Results revealed that corticosteroids' slow effects reduced both prefrontal and hippocampal responses, while no significant rapid actions of corticosteroids were observed. Thereby, this study provides initial evidence for dynamically changing corticosteroid effects on brain regions involved in memory formation in humans.

Residual effects of emotion are reflected in enhanced visual activity after sleep

“…Nevertheless, despite overall poorer memory performance for backgrounds presented with negative (vs. neutral) content, there was greater perceptual processing in those cases where participants managed to successfully retrieve negative contexts, but only following sleep. The fact that group differences were revealed only in neural activity and not in behavior suggests that neural markers may be more sensitive to the effects of study history and sleep than behavioral outcomes, which is consistent with work in many domains that find a similar pattern of results (neural effects in absence of behavioral effects; e.g., Henckens et al, 2012;Van Stegeren, Roozendaal, Kindt, Wolf, & Joëls, 2010). Importantly, because there were no behavioral group differences, the number of correctly recognized objects did not differ across groups, and it is unlikely that memory trace strength differed (as this should have resulted in behavioral group differences).…”

Modulatory mechanisms of cortisol effects on emotional learning and memory: Novel perspectives

“…One recent study directly tested rapid versus slow corticosteroid effects on neural processing associated with memory formation in men (Henckens et al, 2012). Although no behavioral effects of cortisol were found, cortisol’s slow effects reduced prefrontal and hippocampal responses, while no significant rapid effects of cortisol were observed.…”

Physiological Evidence Consistent with Reduced Neuroplasticity in Human Adolescents Born Preterm

“…Emerging evidence also suggests abnormalities in neurochemical and hormone production and responsiveness, although this has yet to be examined in late preterm children. For example, early preterm birth is associated with long-term alterations in cortisol secretion and stress responsiveness (Grunau et al, 2007;Fernandez et al, 2008;Sullivan et al, 2008), and exposure of extremely preterm infants to stressors in the neonatal intensive care unit is associated with regional changes in brain size and functional connectivity (Smith et al, 2011).…”