S4 – The Intricate Relationship between Stressful Events and Memory Processes: Exploring Modulatory Complexity

Numerous studies have indicated that stressful events, emotional arousal, and stress-related hormones can enhance memory consolidation. However, they can also have adverse effects on memory retrieval. Despite abundant empirical evidence identifying a variety of factors modulating different stages of memory, we still face significant challenges in understanding the general rules governing how living organisms manage these modulatory elements. The exploration of how stress and emotional factors influence memory performance presents a challenge due to the inherent complexity of this process. This complexity is reflected in its sensitivity to multiple variables, such as the intensity of the stressor, the memory phase, and the nature of the learned material. Despite the well-established effects of neuromodulators released in response to stress on emotional memory formation, it remains challenging to anticipate whether a specific type of memory will be enhanced, impaired, or prevented following a stressful event. In this symposium, experimental approaches highlighting this complexity will be presented, and some conceptualizations of this issue will be discussed.

Both a Garcia-effect and a continual learning training procedure lead to a similar behavioural phenotype: a decrease in the positive hedonic value assigned by the organism to a food taste. In both procedures snails (Lymnaea stagnalis) show a significant decrease in their feeding response to the food taste. However, the stressors that cause a Garcia-effect do not cause a Configural Learning effect and the stressors that cause a Configural Learning effect do not cause a Garcia-effect memory. We hypothesize that the configural learning training procedure cause a Landscape of Fear to be established in the brain of the snail whilst the Garcia-effect training procedure causes a Landscape of sickness to be established in the nervous system of the snail. I will go over the different and similar molecular pathways that the specific stressors elicit in the nervous system. These data show that the snail is more complicated than most of us imagine as it can easily make a cost benefit analysis of how stressors alter its behaviour.

Kenneth D. Lukowiak
lukowiak@ucalgary.ca
University of Calgary: Calgary, AB, CA
https://profiles.ucalgary.ca/kenneth-daniel-lukowiak

The importance of a dynamic fear memory is that the organism may have the chance to acquire, store and recall critical information, giving to the mnemonic process, the suitable relevance to cope with a changing environment. Such dynamism of a fear memory, and in particular the destabilization/reconsolidation process, is critically affected due to the internal emotional state resulting from, for example, the exposition to an unescapable stressor. Consequently, it represents a traumatic fear memory, pathognomonic of anxiety disorders. Understanding the neurophysiological changes associated to the dynamism of a fear memory, under particular negative emotional states, is relevant for the comprehension of the underlying mechanisms involved in the occurrence of traumatic and persistent memories, as well as for the rebuilding of potential therapeutics tools that could reestablish the adaptive dynamic of the fear memory trace. Here, we will focus on the relevant outcomes observed in animal models of fear learning and memory and its interaction with stressful experiences, along with the observations performed in humans under the psychiatric disorders previously mentioned.

Gastón Calfa
gaston.calfa@unc.edu.ar
Universidad Nacional de Córdoba: Cordoba, Córdoba, AR. Ins. de Farmacología Experimental
https://ifec.fcq.unc.edu.ar/integrantes_ifec/dr-gaston-calfa/&ved=2ahUKEwiWus3KkM-FAxV3gWEGHeNxBwwQFnoECBUQAQ&usg=AOvVaw0P0KzMXr4dHIYUe5QrPsz9

Astrocytes regulate glutamatergic synaptic transmission, presynaptic glutamate release and post synaptic NMDAR activity, via the release of gliotransmitters such as glutamate, D-serine and ATP. Here we summarize recent evidence showing that astroglial gliotransmission is critical for short-term fear memory, stress responses and chronic stress-induced depression.

Jimmy Stehberg
jstehberg@unab.cl
Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Universidad Andres Bello Santiago, Chile.
https://researchers.unab.cl/es/persons/jimmy-stehberg

Contextual fear memories undergo systems consolidation over time, with memory retrieval becoming more dependent on neocortical regions with loss of contextual details, eliciting fear generalization. Here we will address the influence of different training intensities on systems consolidation and memory specificity over time in rats, showing that a strong contextual fear conditioning protocol promotes time-dependent fear generalization associated with post-training corticosterone levels and increased engagement of Salience Network brain regions. The role of glucocorticoid receptors (GR) in the dorsomedial prefrontal cortex and the dorsal hippocampus in the modulation of contextual fear memory specificity will also be discussed.

Raquel V. Fornari
raquel.fornari@ufabc.edu.br
Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Brazil
https://www.ufabc.edu.br/ensino/docentes/raquel-vecchio-fornari