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

Abstract

Summary It has long been known that cortisol affects learning and memory processes. Despite a wealth of research dedicated to cortisol effects on learning and memory, the strength or even directionality of the effects often vary. A number of the factors that alter cortisol’s effects on learning and memory are well-known. For instance, effects of cortisol can be modulated by emotional arousal and the memory phase under study. Despite great advances in understanding factors that explain variability in cortisol’s effects, additional modulators of cortisol effects on memory exist that are less widely acknowledged in current basic experimental research. The goal of the current review is to disseminate knowledge regarding less well-known modulators of cortisol effects on learning and memory. Since several models for the aetiology of anxiety, such as post-traumatic stress disorder (PTSD), incorporate stress and the concomitant release of cortisol as important vulnerability factors, enhanced understanding of mechanisms by which cortisol exerts beneficial as opposed to detrimental effects on memory is very important. Further elucidation of the factors that modulate (or alter) cortisol’s effects on memory will allow reconciliation of seemingly inconsistent findings in the basic and clinical literatures. The present review is based on a symposium as part of the 42nd International Society of Psychoneuroendocrinology Conference, New York, USA, that highlighted some of those modulators and their underlying mechanisms.

Differential effects of stress-induced cortisol responses on recollection and familiarity-based recognition memory

“…A few studies have examined the relationship between pre-learning baseline cortisol levels and free recall in healthy young adults, and have either reported no significant relationship (e.g., Ackerman et al, 2013), or a significant association only under certain conditions, such as after intentional but not incidental encoding (Preuß, Schoofs, & Wolf, 2009), after a night of sleep but not after a no-sleep delay of equal length (Bennion, Steinmetz, Kensinger, & Payne, 2013), and when the materials are emotional rather than neutral (Preuß et al, 2009). Although in the two latter studies a positive association was observed between pre-learning cortisol levels and memory performance, negative relationships between baseline cortisol and memory performance have also been reported in healthy young adults (e.g., Van Honk et al, 2003). However, no previous study that we are aware of has examined the relationship between pre-learning cortisol levels and recognition memory or the processes of recollection and familiarity.…”

“…There is good evidence, primarily from animals but also from human studies, that glucocorticoids influence memory via actions on mineralocorticoid (MR) and glucocorticoid receptors (GR) in medial temporal lobe structures, and that the MR/GR binding ratio can determine how stress impacts memory. Both GRs and MRs are found in the hippocampus (and amygdala), but MRs are found in much lower densities in cortical regions (for a review, see van Ast et al, 2013). Thus, the effects of stress on different memory processes may be a function of the ratio of GR and MR receptors in the brain regions supporting those processes.…”

“…There are a host of possible reasons why the reported effects of stress are not entirely consistent, including possible interactions with the emotional content of the to-be-remembered information (and the psychological arousal induced by the emotional information), and possible differences in stress effects on memory for “central” and “peripheral” details of the information (Payne et al, 2006). Other possible modulatory influences on stress effects include the timing of the stress with respect to memory phases, different actions of glucocorticoid and mineralocorticoid receptors in different brain regions, and individual differences in personality characteristics as well as genetic and epigenetic factors (reviewed by van Ast et al, 2013). …”

“…The trait measures were administered because prior studies suggest that individual differences in emotional regulation strategies and arousal predisposition can mediate responses to external stress (for a review, see van Ast et al, 2013) as well as effects of post-learning manipulations on memory (e.g., Nielson & Lorber, 2009). However, no significant relationship was observed between any of the trait measures and cortisol levels or responses, nor were any relationships observed between trait measures and memory performance, thus we do not discuss the measures further.…”

Modulación de la memoria emocional: una revisión de los principales factores que afectan los recuerdos

“…Hay evidencia que señala que los eventos con contenido emocional se recuerdan en mayor medida que los neutros (Bradley et al, 1992;Cahill & McGaugh, 1995Christianson, 1992;van Ast et al, 2013). Dolcos, LaBar y Cabeza (2004) demostraron que el recuerdo de imágenes (tanto placenteras como displacenteras) con contenido emocional es mayor que el de las imágenes neutras.…”