scholarly journals Functional and evolutionary trade-offs co-occur between two consolidated memory phases in Drosophila melanogaster

2012 ◽  
Vol 279 (1744) ◽  
pp. 4015-4023 ◽  
Author(s):  
Fabrice Lagasse ◽  
Celine Moreno ◽  
Thomas Preat ◽  
Frederic Mery
Keyword(s):  
Evolutionary Dynamics ◽  
Functional Relationship ◽  
Learning Task ◽  
Long Term Memory ◽  
Phenotypic Traits ◽  
Trade Offs ◽  
Memory Phase ◽  
Fitness Benefits ◽  
Benefits And Costs

Memory is a complex and dynamic process that is composed of different phases. Its evolution under natural selection probably depends on a balance between fitness benefits and costs. In Drosophila , two separate forms of consolidated memory phases can be generated experimentally: anaesthesia-resistant memory (ARM) and long-term memory (LTM). In recent years, several studies have focused on the differences between these long-lasting memory types and have found that, at the functional level, ARM and LTM are antagonistic. How this functional relationship will affect their evolutionary dynamics remains unknown. We selected for flies with either improved ARM or improved LTM over several generations, and found that flies selected specifically for improvement of one consolidated memory phase show reduced performance in the other memory phase. We also found that improved LTM was linked to decreased longevity in male flies but not in females. Conversely, males with improved ARM had increased longevity. We found no correlation between either improved ARM or LTM and other phenotypic traits. This is, to our knowledge, the first evidence of a symmetrical evolutionary trade-off between two memory phases for the same learning task. Such trade-offs may have an important impact on the evolution of cognitive capacities. On a neural level, these results support the hypothesis that mechanisms underlying these forms of consolidated memory are, to some degree, antagonistic.

Song and infant-directed speech facilitate word learning

2019 ◽  
Vol 73 (7) ◽  
pp. 1036-1054
Author(s):  
Weiyi Ma ◽  
Anna Fiveash ◽  
Elizabeth Hellmuth Margulis ◽  
Douglas Behrend ◽  
William Forde Thompson
Keyword(s):  
Language Learning ◽  
Word Learning ◽  
Word Association ◽  
Learning Task ◽  
Learning Performance ◽  
Long Term Memory ◽  
Term Memory ◽  
English Speaking ◽  
The Relationship

Two separate lines of research have examined the influence of song and infant-directed speech (IDS—a speech register that includes some melodic features) on language learning, suggesting that the use of musical attributes in speech input can enhance language learning. However, the benefits of these two types of stimuli have never been directly compared. In this investigation, we compared the effects of song and IDS for immediate word learning and long-term memory of the learned words. This study examines whether the highly musical stimuli (i.e., song) would facilitate language learning more than the less musical stimuli (i.e., IDS). English-speaking adults were administered a word learning task, with Mandarin Chinese words presented in adult-directed speech (ADS), IDS, or song. Participants’ word learning performance was assessed immediately after the word learning task (immediate word learning) and then 1 day later (long-term memory). Results showed that both song and IDS facilitated immediate word learning and long-term memory of the words; however, this facilitative effect did not differ between IDS and song, suggesting that the relationship between the degree of musicality and language learning performance is not linear. In addition, song and IDS were found to facilitate the word association process (mapping a label to its referent) rather than the word recognition process. Finally, participants’ confidence in their answers might not differ among ADS, IDS, and sung words.

scholarly journals Heterologous Priming-Boosting with DNA and Modified Vaccinia Virus Ankara Expressing Tryparedoxin Peroxidase Promotes Long-Term Memory against Leishmania major in Susceptible BALB/c Mice

2006 ◽  
Vol 75 (2) ◽  
pp. 852-860 ◽  
Author(s):  
Carmel B. Stober ◽  
Uta G. Lange ◽  
Mark T. M. Roberts ◽  
Antonio Alcami ◽  
Jenefer M. Blackwell
Keyword(s):  
Vaccinia Virus ◽  
Leishmania Major ◽  
Long Term Memory ◽  
Effector Phase ◽  
Modified Vaccinia Virus Ankara ◽  
Tryparedoxin Peroxidase ◽  
Memory Phase ◽  
Ifn Γ ◽  
Susceptible Populations

ABSTRACT Leishmaniasis affects 12 million people, but there are no vaccines in routine clinical use. Th1 polarizing vaccines that elicit long-term protection are required to prevent disease in susceptible populations. We recently showed that heterologous priming-boosting with tryparedoxin peroxidase (TRYP) DNA followed by TRYP-modified vaccinia virus Ankara (TRYP MVA) protected susceptible BALB/c mice from Leishmania major. Here we compared treatment with TRYP DNA with treatment with TRYP DNA/TRYP MVA. We found that equivalent levels of protection during the postvaccination effector phase correlated with equivalent levels of serum immunoglobulin G2a and gamma interferon (IFN-γ) in draining lymph nodes. In contrast, challenge infection during the memory phase revealed that there was enhanced clinical efficacy with TRYP DNA/TRYP MVA. This correlated with higher levels of effector phase splenic IFN-γ, sustained prechallenge levels of memory phase IFN-γ, and a more polarized post-L. major challenge Th1 response compared to the Th2/Treg response. Thus, TRYP DNA/TRYP MVA, but not TRYP DNA alone, provides long-term protection against murine leishmaniasis.

scholarly journals Optimal prediction with resource constraints using the information bottleneck

2020 ◽  
Author(s):  
Vedant Sachdeva ◽  
Thierry Mora ◽  
Aleksandra M. Walczak ◽  
Stephanie Palmer
Keyword(s):  
Resource Constraints ◽  
Internal Representation ◽  
Motion Prediction ◽  
Long Term Memory ◽  
Resource Limitations ◽  
Information Bottleneck ◽  
Trade Offs ◽  
Markovian Dynamics ◽  
The Future

Responding to stimuli requires that organisms encode information about the external world. Not all parts of the signal are important for behavior, and resource limitations demand that signals be compressed. Prediction of the future input is widely beneficial in many biological systems. We compute the trade-offs between representing the past faithfully and predicting the future for input dynamics with different levels of complexity. For motion prediction, we show that, depending on the parameters in the input dynamics, velocity or position coordinates prove more predictive. We identify the properties of global, transferrable strategies for time-varying stimuli. For non-Markovian dynamics we explore the role of long-term memory of the internal representation. Lastly, we show that prediction in evolutionary population dynamics is linked to clustering allele frequencies into non-overlapping memories, revealing a very different prediction strategy from motion prediction.

scholarly journals Word learning deficit among Chinese dyslexic children

2006 ◽  
Vol 33 (1) ◽  
pp. 145-161 ◽  
Author(s):  
CONNIE SUK-HAN HO ◽  
DAVID W. CHAN ◽  
SUK-MAN TSANG ◽  
SUK-HAN LEE ◽  
KEVIN K. H. CHUNG
Keyword(s):  
Word Learning ◽  
Word Association ◽  
Learning Task ◽  
Control Group ◽  
Long Term Memory ◽  
New Words ◽  
Dyslexic Group ◽  
Word Writing ◽  
Own Name

The present study examined word learning difficulties in Chinese dyslexic children, readers of a nonalphabetic script. A total of 105 Hong Kong Chinese children were recruited and divided into three groups: Dyslexic (mean age 8;8), CA control (mean age 8;9), and RL control (mean age 6;11). They were given a word learning task and a familiar word writing task. It was found that the Dyslexic group performed less well than the RL group in learning irregular words over trials but not the regular ones. Error analyses showed that the Dyslexic group made more orthographic and word association errors but less intra-wordlist interference errors than the RL control group. The Dyslexic group also performed significantly less well than both control groups in writing familiar words (e.g. their own name). These findings suggest that Chinese dyslexic children have difficulty learning new words, especially irregular ones, and retaining overlearned words in long-term memory. We conclude that Chinese dyslexic children have a specific impairment in word learning like their alphabetic counterparts.

scholarly journals Adaptive repulsion of long-term memory representations is triggered by event similarity

2020 ◽  
Author(s):  
Avi J. H. Chanales ◽  
Alexandra G. Tremblay-McGaw ◽  
Brice A. Kuhl
Keyword(s):  
Learning Task ◽  
Task Demands ◽  
Supplementary Information ◽  
Long Term Memory ◽  
Memory Interference ◽  
Color Similarity ◽  
Color Memory ◽  
Fourth Experiment ◽  
Repulsion Effect

ABSTRACTWe tested whether similarity between events triggers an adaptive repulsion of long-term memories. Subjects completed an associative learning task in which objects were paired with faces. Critically, the objects consisted of pairs that were identical except for their color values, which were parametrically varied in order to manipulate interference. Performance on associative memory tests confirmed that color similarity robustly influenced interference. Separate tests of color memory showed that high similarity triggered a repulsion of long-term memories, wherein remembered colors were biased away from colors of competing objects. This repulsion effect was replicated across three experiments. In a fourth experiment, the repulsion effect was fully eliminated when task demands promoted integration, instead of discrimination, of similar memories. Finally, we show that repulsion of color memory was highly adaptive: greater repulsion was associated with less memory interference. These findings reveal that similarity between events triggers adaptive distortions in how events are remembered.SUPPLEMENTARY INFORMATIONThree supplementary figures are included.

scholarly journals Intrinsically regulated learning is modulated by synaptic dopamine availability

2018 ◽  
Author(s):  
Pablo Ripollés ◽  
Laura Ferreri ◽  
Ernest Mas-Herrero ◽  
Helena Alicart ◽  
Alba Gómez-Andrés ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Learning Task ◽  
Pharmacological Intervention ◽  
Long Term Memory ◽  
Behavioral Measures ◽  
Double Blind ◽  
Learning Success ◽  
New Information ◽  
Regulated Learning

ABSTRACTWe recently provided evidence that an intrinsic reward-related signal—triggered by successful learning in absence of any external feedback—modulated the entrance of new information into long-term memory via the activation of the dopaminergic midbrain, hippocampus, and ventral striatum (the SN/VTA-Hippocampal loop; Ripollés et al., 2016). Here, we used a double-blind, within-subject randomized pharmacological intervention to test whether this learning process is indeed dopamine-dependent. A group of healthy individuals completed three behavioural sessions of our learning task after the intake of different pharmacological treatments: a dopaminergic precursor, a dopamine receptor antagonist or a placebo. Results show that the pharmacological intervention bidirectionally modulated behavioral measures of both learning and pleasantness, inducing memory benefits after 24 hours only for those participants with a high sensitivity to reward. These results provide causal evidence for a dopamine-dependent mechanism instrumental in intrinsically regulated learning, and further suggest that subject-specific dopamine sensitivity drastically alters learning success.

scholarly journals Ultrastructural Evidence for a Role of Astrocytes and Glycogen-Derived Lactate in Learning-Dependent Synaptic Stabilization

2019 ◽  
Vol 30 (4) ◽  
pp. 2114-2127 ◽  
Author(s):  
E Vezzoli ◽  
C Calì ◽  
M De Roo ◽  
L Ponzoni ◽  
E Sogne ◽  
...  
Keyword(s):  
Structural Changes ◽  
Glycogen Metabolism ◽  
Selective Inhibition ◽  
Long Term Potentiation ◽  
Learning Task ◽  
Long Term Memory ◽  
Spine Density ◽  
Synaptic Changes

Abstract Long-term memory formation (LTM) is a process accompanied by energy-demanding structural changes at synapses and increased spine density. Concomitant increases in both spine volume and postsynaptic density (PSD) surface area have been suggested but never quantified in vivo by clear-cut experimental evidence. Using novel object recognition in mice as a learning task followed by 3D electron microscopy analysis, we demonstrate that LTM induced all aforementioned synaptic changes, together with an increase in the size of astrocytic glycogen granules, which are a source of lactate for neurons. The selective inhibition of glycogen metabolism in astrocytes impaired learning, affecting all the related synaptic changes. Intrahippocampal administration of l-lactate rescued the behavioral phenotype, along with spine density within 24 hours. Spine dynamics in hippocampal organotypic slices undergoing theta burst-induced long-term potentiation was similarly affected by inhibition of glycogen metabolism and rescued by l-lactate. These results suggest that learning primes astrocytic energy stores and signaling to sustain synaptic plasticity via l-lactate.

scholarly journals Sleep after learning aids the consolidation of factual knowledge, but not relearning

SLEEP ◽  
2020 ◽  
Author(s):  
James N Cousins ◽  
Teck Boon Teo ◽  
Zhi Yi Tan ◽  
Kian F Wong ◽  
Michael W L Chee
Keyword(s):  
Learning Outcomes ◽  
Learning Task ◽  
Memory Effects ◽  
Long Term Memory ◽  
Factual Knowledge ◽  
Nocturnal Sleep ◽  
Learning Session ◽  
Learning Aids ◽  
Before And After

Abstract Study Objectives Sleep strengthens and reorganizes declarative memories, but the extent to which these processes benefit subsequent relearning of the same material remains unknown. It is also unclear whether sleep-memory effects translate to educationally realistic learning tasks and improve long-term learning outcomes. Methods Young adults learned factual knowledge in two learning sessions that were 12 h apart and separated by either nocturnal sleep (n = 26) or daytime wakefulness (n = 26). Memory before and after the retention interval was compared to assess the effect of sleep on consolidation, while memory before and after the second learning session was compared to assess relearning. A final test 1 week later assessed whether there was any long-term advantage to sleeping between two study sessions. Results Sleep significantly enhanced consolidation of factual knowledge (p = 0.01, d = 0.72), but groups did not differ in their capacity to relearn the materials (p = 0.72, d = 0.10). After 1 week, a numerical memory advantage remained for the sleep group but was no longer significant (p = 0.21, d = 0.35). Conclusions Reduced forgetting after sleep is a robust finding that extends to our ecologically valid learning task, but we found no evidence that sleep enhances relearning. Our findings can exclude a large effect of sleep on long-term memory after 1 week, but hint at a smaller effect, leaving open the possibility of practical benefits from organizing study sessions around nocturnal sleep. These findings highlight the importance of revisiting key sleep-memory effects to assess their relevance to long-term learning outcomes with naturalistic learning materials.

scholarly journals Treating symptomatic infections and the co-evolution of virulence and drug resistance

2020 ◽  
Author(s):  
Samuel Alizon
Keyword(s):  
Evolutionary Dynamics ◽  
Adaptive Dynamics ◽  
Drug Resistant ◽  
Treatment Rate ◽  
Virulence Evolution ◽  
Trade Offs ◽  
Virulent Strains ◽  
Host Mortality ◽  
Parameter Values

AbstractAntimicrobial therapeutic treatments are by definition applied after the onset of symptoms, which tend to correlate with infection severity. Using mathematical epidemiology models, I explore how this link affects the coevolutionary dynamics between the virulence of an infection, measured via host mortality rate, and its susceptibility to chemotherapy. I show that unless resistance pre-exists in the population, drug-resistant infections are initially more virulent than drug-sensitive ones. As the epidemic unfolds, virulence is more counter-selected in drug-sensitive than in drug-resistant infections. This difference decreases over time and, eventually, the exact shape of genetic trade-offs govern long-term evolutionary dynamics. Using adaptive dynamics, I show that two types of evolutionary stable strategies (ESS) may be reached in the context of this simple model and that, depending on the parameter values, an ESS may only be locally stable. In general, the more the treatment rate increases with virulence, the lower the ESS value. Overall, both on the short-term and long-term, having treatment rate depend on infection virulence tend to favour less virulent strains in drug-sensitive infections. These results highlight the importance of the feedbacks between epidemiology, public health policies and parasite evolution, and have implications for the monitoring of virulence evolution.

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