Stress and long-term memory retrieval: a systematic review

Abstract Introduction The experience of stressful events can alter brain structures involved in memory encoding, storage and retrieval. Here we review experimental research assessing the impact of the stress-related hormone cortisol on long-term memory retrieval. Method A comprehensive literature search was conducted on PubMed, Web of Science and PsycNet databases with the following terms: "stress," "long-term memory," and "retrieval." Studies were included in the review if they tested samples of healthy human participants, with at least one control group, and with the onset of the stress intervention occurring after the encoding phase and shortly (up to one hour) before the final memory test. Results Thirteen studies were included in the qualitative synthesis (N = 962) and were classified according to the time elapsed between stress induction and memory retrieval (stress-retrieval delay), the stress-inducing protocol (stressor), the time of day in which stress induction took place, sex, and age of participants. Most studies induced stress with the Trier Social Stress Test (TSST) between 15 and 25 minutes before the final memory (mostly recall) test and showed significant increases in cortisol levels and memory impairment. Discussion The reviewed studies indicate that stress does impair retrieval, particularly when induced with the TSST, in the afternoon, up to 45 minutes before the onset of the final memory test, in healthy young men. These results may inform future research on the impact of stress-induced cortisol surges on memory retrieval.

Semantic memory, but not education or intelligence, moderates cognitive aging: a cross-sectional study

Objective: Aging studies regularly assume that years of education are a protective factor for baseline cognition. In developing countries with specific sociocultural issues, this relationship may not work as expected, and an unmet need remains for alternative resilience factors. This study aimed to analyze different moderators for the relationship between aging and general cognition that could reflect better protective factors. Methods: One hundred and fourteen Brazilian older adults, deemed healthy by global cognition, absence of psychiatric symptoms, or neurological history, participated in this cross-sectional study. Moderators for the relationship between age and global cognition included education, intelligence, and occupational factors. Semantic memory was added as a protective factor reflecting culturally acquired conceptual knowledge. Results: As expected, age alone is a predictor of global cognitive scores; surprisingly, however, education, intelligence, and occupation were not moderators of the association. Semantic memory was a significant moderator (p = 0.007), indicating that knowledge acquired during life may be a protective factor. Conclusion: In developing countries, the use of resilience factors based only on years of education may be misleading. Sociocultural issues influence the educational system and achievement and, consequently, affect the use of this simple measure. Resilience-factor studies should consider using crystallized abilities when studying populations with sociocultural particularities.

Sobre la memoria, la conciencia y el pensamiento en américa latina: Entre la laguna y el pantano / On the memory, consciousness, and thought in latin america: between the lagoon and the swamp

En el presente texto se desarrollan algunas rutas de análisis en torno a la pregunta ¿cómo incorporar éticamente el problema en sus acciones cotidianas, y del mismo modo, cómo evitar las exitosas estrategias del olvido y la indiferencia?; Se hace énfasis en la ganada importancia que tienen los procesos populares sobre todo juveniles, en tanto que, gracias a sus narrativas, acrecientan y triunfan cotidianamente sobre las retóricas autoritarias quebuscan silenciar la memoria.

Some routes of analyses around the following question: How to incorporate ethically the problem in their daily actions, and similarly, how to avoid the successful strategies of oblivion and indifference? are addressed in this paper. Certain emphasis is made on thegained importance that the popular processes have specially those related to the youth, while, thanks to their narratives, they increase and succeed, on a daily basis, over the authoritarian rhetoric seeking to silence memory.

NF-kB (Nuclear factor kappa B) su relación con aprendizaje, memoria y neurogénesis en el hipocampo / NF-kB (nuclear factor NF-kB) its relationship with learning, memory and neurogenesis in the hippocampus

En esta revisión bibliográfica focalizaremos sobre la importancia del factor de transcripción NF-kB en el sistema nervioso. NF-kB es una familia de factores de transcripción, conservada evolutivamente, involucrada en los mecanismos básicos celulares de la respuesta inmune, la inflamación, el desarrollo y la apoptosis, que también se expresa en el sistema nervioso central, especialmente en las áreas implicadas en el procesamiento de la memoria, y es activado por señales como el glutamato y el Ca2+. En los últimos años, numerosas investigaciones han comprobado su rol fundamental como parte de la vía de señalización en la regulación de la expresión de genes implicados en la memoria de largo término. Se comprobó la importancia del NF-kB en el neurodesarrollo, en la regulación de la supervivencia neuronal y de la neurogénesis en el hipocampo del adulto. También se comprobó un aumento de la actividad del NF-kB en el cerebro en modelos animales de depresión. Este efecto estaría mediado por el incremento de la IL-6, proinflamatoria. En el modelo de depresión de oscuridad constante también se observaron alteraciones en los niveles de las proteínas hipocampales per2 y npas2, vinculadas al ritmo circadiano. El conocimiento de la neurobiología de este factor de transcripción nos permitirá vislumbrar sus potenciales implicaciones clínicas, así como la posibilidad de influir farmacológicamente: en las memorias traumáticas, en la declinación cognitiva y en los trastornos del ánimo.

In this literature review, we will focus on the importance of the transcription factor NF-kB in the nervous system. NF-kB is a transcription factor family, evolutionarily conserved, which is involved in the basic mechanisms involved in the cellular immune response, inflammation, development and apoptosis, which is also expressed in the Central Nervous System, especially in the areas involved in the processing of memory, and it is activated by signals such as glutamate and Ca2+. In recent years, numerous studies have proven its key role as part of the signaling path in the regulation of the expression of genes in the long-term memory. The importance of NF-kB in neurodevelopment has also been verified in relation to the regulation of neuronal survibal and the neurogenesis in the adult hippocampus. An increase in the NF-kB activity in the brain has also been found in animal models of depression. This effect would be mediated by an increase in pro-inflammatory IL-6. In the model of Constant Drkness Depression, an alteration of the hippocampal protein levels per2 and npas2 linked to circadian rhythm was also observed. Knowing the neurobiology of this transcription factor will allow us to glimpse their potential clinical implications, and the possibility to influence pharmacologically in traumatic memories, in cognitive decline, and mood disorders.