The hippocampus in evolutionary perspective

Se trata de un congreso anual que reúne a investigadores de laboratorios de universidades tanto nacionales como extranjeras con el fin de estudiar procesos de aprendizaje, memoria, percepción, atención y sus bases cerebrales tanto en animales humanos como no humanos.Recent findings challenge the view that the hippocampal cognitive map is fundamentally spatial. In the first part of this talk I will consider whether the hippocampus is part of a domaingeneral or domain-specific system. Did it, in other words, evolve in response to selective pressures imposed by spatial conditions of the environment, or did the pressure come from the need for "relational" binding in general? In the second part of the talk I will discuss the longitudinal axis of the hippocampus, which supports spatial maps of different "scales". What is the function of this multi-scale system, and did all scales evolve simultaneously? Both of these issues raise questions that can be approached from a comparative perspective, and I will close by suggesting some possibilities.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Facultad de Psicología y Logopedia de la Universidad de Málaga. Departamento de Psicología Básica de la Universidad de Málaga. Sociedad Española de Psicología Experimenta

Reconsolidation of episodic memories:a subtle reminder triggers integration of new information

Recent demonstrations of “reconsolidation” suggest that memories can be modified when they are reactivated. Reconsolidation has been observed in human procedural memory and in implicit memory in infants. This study asks whether episodic memory undergoes reconsolidation. College students learned a list of objects on Day 1. On Day 2, they received a reminder or not, and then learned a second list. Memory for List 1 was tested immediately on Day 2 (Experiment 2) or on Day 3 (Experiment 1). Although the reminder did not moderate the number of items recalled from List 1 on either day, subjects who received a reminder incorrectly intermixed items from the second list when recalling List 1 on Day 3. Experiment 2 showed that this effect does not occur immediately and thus is time-dependent. The reminder did not affect memory for List 2 on Day 3 (Experiment 3), demonstrating that modification occurred only for the original memory (List 1). The study demonstrates the crucial role of reminders for the modification of episodic memory, that reconsolidation of episodic memory is time-dependent, and, in contrast to previous reconsolidation findings, that reconsolidation is also a constructive process, one that supports the incorporation of new information in memory

Autobiographical Memory Retrieval and Hippocampal Activation as a Function of Repetition and the Passage of Time

Multiple trace theory (MTT) predicts that hippocampal memory traces expand and strengthen as a function of repeated memory retrievals. We tested this hypothesis utilizing fMRI, comparing the effect of memory retrieval versus the mere passage of time on hippocampal activation. While undergoing fMRI scanning, participants retrieved remote autobiographical memories that had been previously retrieved either one month earlier, two days earlier, or multiple times during the preceding month. Behavioral analyses revealed that the number and consistency of memory details retrieved increased with multiple retrievals but not with the passage of time. While all three retrieval conditions activated a similar set of brain regions normally associated with autobiographical memory retrieval including medial temporal lobe structures, hippocampal activation did not change as a function of either multiple retrievals or the passage of time. However, activation in other brain regions, including the precuneus, lateral prefrontal cortex, parietal cortex, lateral temporal lobe, and perirhinal cortex increased after multiple retrievals, but was not influenced by the passage of time. These results have important implications for existing theories of long-term memory consolidation

Cognitive Neuroscience Analyses of Memory: A Historical Perspective

As part of the general trend toward interdisciplinary research in recent years, a growing number of investigators have come to consider both cognitive and neuroscientific perspectives when theorizing about memory. Although such cognitive neuroscience analyses are a relatively recent development, the approach has precedents in earlier scientific thinking about memory. In this article we present a historical review of three major issues in memory research---consolidation processes, the nature of memory representations, and multiple memory systems. We discuss the nature of the relation between cognitive and neuroscientific approaches to each of these issues with respect to the distinction between collateral, complementary, and convergent relations (Schacter, 1986). Although some early investigators offered analyses that linked psychological and physiological perspectives, there is little historical evidence of systematic or sustained interdisciplinary research. However, more recent work, especially with respect to hypotheses about memory systems, suggests progress toward establishing programmatic interdisciplinary research.Psycholog

Curiosity-driven memory enhancement persists over time but does not benefit from post-learning sleep

Sleep-dependent memory processing is dependent on several factors at learning, including emotion, encoding strength, and knowledge of future relevance. Recent work documents the role of curiosity on learning, showing that memory associated with high-curiosity encoding states is retained better and that this effect may be driven by activity within the dopaminergic circuit. Here, we examined whether this curiosity effect was enhanced by or dependent on sleep-related consolidation. Participants learned the answers to trivia questions that they had previously rated on a curiosity scale, and they were shown faces between each question and answer presentation. Memory for these answers and faces was tested either immediately or after a 12-hour delay containing sleep or wakefulness, and polysomnography data was collected for a subset of the sleep participants. Although the curiosity effect for both the answers and incidentally-learned faces was replicated in immediate tests and after the 12-hour delay, the effect was not impacted by the presence of sleep in either case, nor did the effect show a relationship with total sleep time or time in slow-wave sleep. This study suggests that curiosity may be a learning factor that is not subsequently affected by sleep-dependent memory consolidation, but more work ought to examine the role of sleep on curiosity-driven memory in other contexts

spatial navigation deficit in the Morris water maze after single high dose of neonatal X-ray irradiation

ABSTRACT Ambiguous spatial behavior deficits induced in adult rats by different types of dentate gyrus lesions were examined by subjecting neonatal rats to x-ray irradiation, which reduces the granule cell population in fascia dentata without affecting the number of hilar neurons and pyramidal cells of Ammon's horn. Three-to six-month-old irradiated and intact male Long-Evans rats were tested in the Morris water maze. Four experiments were done. (i) Rats were trained to find an invisible escape platform, when started from any of four equidistant points at the circumference of the pool. (ii) The same rats then were trained to find a visible platform in the same pool. Poor performance of irradiated rats in both experiments suggested a visual deficit. (iii) Navigation in the absence of visual cues was studied in other rats trained in total darkness to find the escape platform under conditions of fixed start-fixed goal geometry. (iv) Contribution of nonvisual allocentric cues and egocentric path integration mechanisms to spatial performance of the above rats was tested in darkness after rotating both the start and goal positions by 90؇ clockwise. Impairment of irradiated rats in Exp. 3 and 4 and histological examination of their brains support the conclusion that 60-70% reduction of granule cells in the dorsal hippocampus causes significant deterioration in both allocentric and egocentric orientation

The brain decade in debate: I. Neurobiology of learning and memory

This article is a transcription of an electronic symposium in which some active researchers were invited by the Brazilian Society for Neuroscience and Behavior (SBNeC) to discuss the last decade's advances in neurobiology of learning and memory. The way different parts of the brain are recruited during the storage of different kinds of memory (e.g., short-term vs long-term memory, declarative vs procedural memory) and even the property of these divisions were discussed. It was pointed out that the brain does not really store memories, but stores traces of information that are later used to create memories, not always expressing a completely veridical picture of the past experienced reality. To perform this process different parts of the brain act as important nodes of the neural network that encode, store and retrieve the information that will be used to create memories. Some of the brain regions are recognizably active during the activation of short-term working memory (e.g., prefrontal cortex), or the storage of information retrieved as long-term explicit memories (e.g., hippocampus and related cortical areas) or the modulation of the storage of memories related to emotional events (e.g., amygdala). This does not mean that there is a separate neural structure completely supporting the storage of each kind of memory but means that these memories critically depend on the functioning of these neural structures. The current view is that there is no sense in talking about hippocampus-based or amygdala-based memory since this implies that there is a one-to-one correspondence. The present question to be solved is how systems interact in memory. The pertinence of attributing a critical role to cellular processes like synaptic tagging and protein kinase A activation to explain the memory storage processes at the cellular level was also discussed.University of Bristol Department of PsychologyUniversidade Federal de São Paulo (UNIFESP) Departamento de PsicobiologiaUniversity of California Center for Neurobiology of Learning and Memory Department of Neurobiology and BehaviorUniversity of California Neuropsychiatric InstituteUniversidade Federal do Rio Grande do Sul Instituto de Biociências Departamento de BioquímicaUniversity of Edinburgh Department of NeuroscienceUniversity of Arizona Department of PsychologyNorthwestern UniversityUniversidade de São Paulo Instituto de Biociências Departamento de FisiologiaUniversidade Federal do Paraná Departamento de Farmacologia Laboratório de Fisiologia e Farmacologia do Sistema Nervoso CentralUNIFESP, Depto. de PsicobiologiaSciEL

High temperature affects olive fruit fly populations in California's Central Valley

Olive fruit fly commonly infests olives in California’s Central Valley. Field studies indicate that trap counts for olive fruit fly adults in pesticide-free sites decrease in mid- and late summer and then rebound from September to November. Part of this decline is associated with heat stress that the flies experience in mid-July and August. Studies have shown that adult flies will die within a few days if they cannot access adequate amounts of water and carbohydrates. Flight ability is dramatically reduced when resources are unavailable. Olive fruit fly adults may use black scale honeydew as a carbohydrate source to help them survive hot periods. Heat also affects the fly’s reproduction and immature stages within olive fruit. Geographic information system (GIS) maps may be useful for predicting the risk of olive fruit fly infestation