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1.
Commun Biol ; 5(1): 896, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36050393

RESUMO

Similarity-based categorization can be performed by memorizing category members as exemplars or by abstracting the central tendency of the category - the prototype. In similarity-based categorization of stimuli with clearly identifiable dimensions from two categories, prototype representations were previously located in the hippocampus and the ventromedial prefrontal cortex (vmPFC) and exemplar representations in areas supporting visual memory. However, the neural implementation of exemplar and prototype representations in perceptual similarity-based categorization of single categories is unclear. To investigate these representations, we applied model-based univariate and multivariate analyses of functional imaging data from a dot-pattern paradigm-based task. Univariate prototype and exemplar representations occurred bilaterally in visual areas. Multivariate analyses additionally identified prototype representations in parietal areas and exemplar representations in the hippocampus. Bayesian analyses supported the non-presence of prototype representations in the hippocampus and the vmPFC. We additionally demonstrate that some individuals form both representation types simultaneously, probably granting flexibility in categorization strategies.


Assuntos
Memória , Córtex Pré-Frontal , Teorema de Bayes , Hipocampo , Humanos , Córtex Pré-Frontal/diagnóstico por imagem
2.
PLoS One ; 17(9): e0273455, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36070290

RESUMO

An important task for the law enforcement is to assess the accuracy of eyewitness testimonies. Recent research show that indicators of effortful memory retrieval, such as pausing and hedging (e.g. "I think", "maybe"), are more common in incorrect recall. However, a limitation in these studies is that participants are interviewed shortly after witnessing an event, as opposed to after greater retention intervals. We set out to mitigate this shortcoming by investigating the retrieval effort-accuracy relationship over time. In this study, participants watched a staged crime and were interviewed directly afterwards, and two weeks later. Half the participants also carried out a repetition task during the two-week retention interval. Results showed that the retrieval-effort cues Delays and Hedges predicted accuracy at both sessions, including after repetition. We also measured confidence, and found that confidence also predicted accuracy over time, although repetition led to increased confidence for incorrect memories. Moreover, retrieval-effort cues partially mediated between accuracy and confidence.


Assuntos
Memória , Rememoração Mental , Crime , Sinais (Psicologia) , Humanos
3.
J Behav Ther Exp Psychiatry ; 77: 101767, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36113904

RESUMO

BACKGROUND AND OBJECTIVES: Basic research suggest behavioral strategies for interferencing the reconsolidation of fear memories to be a promising approach in reducing clinical fears. However, first clinical studies revealed mixed results highlighting the need to identify boundary conditions. We experimentally tested the specific hypothesis that post-retrieval threat exposure prevents context renewal usually observed in protocols without fear memory reactivation. METHODS: In a preliminary investigation forty-three individuals with claustrophobic fears reactivated the individual phobic memory or not during a guided emotional imagery task and then performed standardized threat exposure to provide new information for updating the original memory. During retests seven and 28 days later, the context was different from that during treatment in half of the subjects. RESULTS: In those who were guided, the fear memory was successfully reactivated as indexed by increased skin conductance level (SCL) during the imagery of personal scenes relative to neutral scenes. During retests the subjects of the memory non-activation group showed a return of reported fear after context change that, however, was not observed after post-retrieval exposure. In line, autonomic arousal (SCL) decreased over time in the memory reactivation group only if the context changed during retest. LIMITATIONS: Limited sample size and the inclusion of an analog sample reduce the generalizability of the results. CONCLUSIONS: The reactivation of fear memory prior to treatment through guided imagery of past personal phobic situations prevented contextual renewal of phobic fears which was observed in those subjects without reactivation of memory.


Assuntos
Medo , Memória , Emoções , Medo/psicologia , Humanos , Memória/fisiologia
4.
PLoS One ; 17(9): e0274101, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36074790

RESUMO

Many studies have focused on understanding memory processes due to their importance in daily life. Differences in timing and power spectra of brain signals during encoding task have been linked to later remembered items and were recently used to predict memory retrieval performance. However, accuracies remain low when using non-invasive methods for acquiring brain signals, mainly due to the low spatial resolution. This study investigates the prediction of successful retrieval using estimated source activity corresponding either to cortical or subcortical structures through source localization. Electroencephalogram (EEG) signals were recorded while participants performed a declarative memory task. Frequency-time analysis was performed using signals from encoding and retrieval tasks to confirm the importance of neural oscillations and their relationship with later remembered and forgotten items. Significant differences in the power spectra between later remembered and forgotten items were found before and during the presentation of the stimulus in the encoding task. Source activity estimation revealed differences in the beta band power over the medial parietal and medial prefrontal areas prior to the presentation of the stimulus, and over the cuneus and lingual areas during the presentation of the stimulus. Additionally, there were significant differences during the stimuli presentation during the retrieval task. Prediction of later remembered items was performed using surface potentials and estimated source activity. The results showed that source localization increases classification performance compared to the one using surface potentials. These findings support the importance of incorporating spatial features of neural activity to improve the prediction of memory retrieval.


Assuntos
Memória , Rememoração Mental , Encéfalo , Mapeamento Encefálico , Eletroencefalografia , Humanos
5.
Nat Commun ; 13(1): 4733, 2022 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-36096993

RESUMO

Memories are stored in the brain as cellular ensembles activated during learning and reactivated during retrieval. Using the Tet-tag system in mice, we label dorsal dentate gyrus neurons activated by positive, neutral or negative experiences with channelrhodopsin-2. Following fear-conditioning, these cells are artificially reactivated during fear memory recall. Optical stimulation of a competing positive memory is sufficient to update the memory during reconsolidation, thereby reducing conditioned fear acutely and enduringly. Moreover, mice demonstrate operant responding for reactivation of a positive memory, confirming its rewarding properties. These results show that interference from a rewarding experience can counteract negative affective states. While memory-updating, induced by memory reactivation, involves a relatively small set of neurons, we also find that activating a large population of randomly labeled dorsal dentate gyrus neurons is effective in promoting reconsolidation. Importantly, memory-updating is specific to the fear memory. These findings implicate the dorsal dentate gyrus as a potential therapeutic node for modulating memories to suppress fear.


Assuntos
Medo , Hipocampo , Animais , Medo/fisiologia , Hipocampo/fisiologia , Aprendizagem , Memória/fisiologia , Camundongos , Neurônios/fisiologia
6.
Molecules ; 27(17)2022 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-36080178

RESUMO

Silk protein products have been used for a wide range of applications. This review focuses on the studies conducted relative to cognitive functions with silk fibroin enzyme hydrolysates (FEH) in humans and animals. All known studies reported in PubMed and Google Scholar have been included. Studies have been conducted on children, high school and college students, adults and seniors, ranging in ages from 7-92 years. Doses of 200-600 mg silk FEH per day for three weeks to 16 weeks have been used. Based on these studies, it can be concluded that silk FEH exhibit beneficial cognitive effects with respect to memory and learning, attention, mental focus, accuracy, memory recall, and overall memory and concentration. These conclusions are supported by studies in rats and mice. Mechanistic studies that have been conducted in animals and cell culture systems are also reviewed. These studies indicate that silk FEH exerts its positive effects on memory and learning by providing neuroprotection via a complex mechanism involving its potent antioxidant and inflammation-inhibiting activities. Acetylcholine (ACh) is secreted by cholinergic neurons, and plays a role in encoding new information. Silk FEH were shown to decrease the levels of the pro-oxidant and pro-inflammatory mediators interlukin-1 (IL-1ß), IL-6 and tumor necrosis factor-alpha (TNF-α), protecting the cholinergic system from oxidative stress, thus enhancing ACh levels in the brain, which is known to promote cognitive functions. In addition, the expression of brain-derived neurotrophic factor (BNDF), which is involved in the survival of neurons, is enhanced, and an increase in the expression of the phosphorylated cAMP response element-binding protein (p-CREB) occurs, which is known to play a positive role in cognitive functions. No adverse effects have been reported in association with the use of silk FEH.


Assuntos
Fibroínas , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Criança , Cognição , Fibroínas/farmacologia , Humanos , Aprendizagem , Memória , Camundongos , Pessoa de Meia-Idade , Ratos , Seda/farmacologia , Adulto Jovem
7.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1753-1756, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085854

RESUMO

Traumatic Brain Injury (TBI) patients present high levels of physical stress, which in some situations can manifest as Plateau Wave (PW) episodes. This intense stress phenomenon can be evidenced by Heart Rate Variability (HRV). Thus, the multivariate and simultaneous analysis of cardio-cerebrovascular oscillations, involving the RR intervals, mean arterial pressure (MAP) and the amplitude of intracranial pressure (AMP), will be useful to understand the interconnections between body signals, allowing the interpretation of the combined activity of pathophysiological mechanisms. In this work, the multiscale representation of the Transfer Entropy (TE) and of its decomposition in the network of these three interacting processes is obtained, based on a Vector AutoRegressive Fractionally Integrated (VARFI) framework for Gaussian processes. This method allows to assess directed interactions and to quantify the information flow accounting for the simultaneous presence of short-term dynamics and long-range correlations. The results show that the baseline RR, but not MAP can provide information about the possibility of a PW arising. During PW, the long-term correlations highlight synergistic interactions between MAP and AMP processes on RR. The multiscale decomposition of the information along with the incorporation of the long term correlations allowed a better description of HRV during PW, highlighting the fact that the HRV mirrors this cerebrovascular phenomena.


Assuntos
Lesões Encefálicas Traumáticas , Pressão Intracraniana , Monofosfato de Adenosina , Frequência Cardíaca , Humanos , Memória
8.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1036-1040, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36086289

RESUMO

Automatic interpretation of cluster structure in rapidly arriving data streams is essential for timely detection of interesting events. Human activities often contain bursts of repeating patterns. In this paper, we propose a new relative of the Visual Assessment of Cluster Tendency (VAT) model, to interpret cluster evolution in streaming activity data where shapes of recurring patterns are important. Existing VAT algorithms are either suitable only for small batch data and unscalable to rapidly evolving streams, or cannot capture shape patterns. Our proposed incremental algorithm processes streaming data in chunks and identifies repeating patterns or shapelets from each chunk, creating a Dictionary-of-Shapes (DoS) that is updated on the fly. Each chunk is transformed into a lower dimensional representation based on it's distance from the shapelets in the current DoS. Then a small set of transformed chunks are sampled using an intelligent Maximin Random Sampling (MMRS) scheme, to create a scalable VAT image that is incrementally updated as the data stream progresses. Experiments on two upper limb activity datasets demonstrate that the proposed method can successfully and efficiently visualize clusters in long streams of data and can also identify anomalous movements.


Assuntos
Algoritmos , Memória , Análise por Conglomerados , Humanos
9.
Proc Natl Acad Sci U S A ; 119(32): e2201578119, 2022 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-35914156

RESUMO

Passive priming of prior knowledge to assimilate ongoing experiences underlies advanced cognitive processing. However, the necessary neural dynamics of memory assimilation remains elusive. Uninstructed brain could also show boosted creativity, particularly after idling states, yet it remains unclear whether the idling brain can spontaneously spark relevant knowledge assimilations. We established a paradigm that links/separates context-dependent memories according to geometrical similarities. Mice exploring one of four contexts 1 d before undergoing contextual fear conditioning in a square context showed a gradual fear transfer to preexposed geometrically relevant contexts the next day, but not after 15 min. Anterior cingulate cortex neurons representing relevant, rather than distinct, memories were significantly coreactivated during postconditioning sleep only, before their selective integration the next day during testing. Disrupting sleep coreactivations prevented assimilation while preserving recent memory consolidation. Thus, assimilating pertinent memories during sleep through coreactivation of their respective engrams represents the neural underpinnings of sleep-triggered implicit cortical learning.


Assuntos
Encéfalo , Aprendizagem , Consolidação da Memória , Sono , Animais , Encéfalo/fisiologia , Medo/fisiologia , Giro do Cíngulo/fisiologia , Memória , Consolidação da Memória/fisiologia , Camundongos
10.
Int J Mol Sci ; 23(15)2022 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-35955662

RESUMO

Memories are lasting representations over time of associations between stimuli or events. In general, the relatively slow consolidation of memories requires protein synthesis with a known exception being the so-called Anesthesia Resistant Memory (ARM) in Drosophila. This protein synthesis-independent memory type survives amnestic shocks after a short, sensitive window post training, and can also emerge after repeated cycles of training in a negatively reinforced olfactory conditioning task, without rest between cycles (massed conditioning-MC). We discussed operational and molecular mechanisms that mediate ARM and differentiate it from protein synthesis-dependent long-term memory (LTM) in Drosophila. Based on the notion that ARM is unlikely to specifically characterize Drosophila, we examined protein synthesis and MC-elicited memories in other species and based on intraspecies shared molecular components and proposed potential relationships of ARM with established memory types in Drosophila and vertebrates.


Assuntos
Anestesia , Proteínas de Drosophila , Animais , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Memória , Memória de Longo Prazo
11.
J Womens Health (Larchmt) ; 31(8): 1087-1096, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35980243

RESUMO

Background: The experience and even existence of cognitive deficits in the postpartum period is uncertain, with only a few scientific studies, reporting inconsistent results. Methods: In this study, we investigate cognition in 86 women (43 first-time mothers 1 year postpartum and 43 non-mothers). Results: Mothers and non-mothers showed no significant differences on measures of objective cognition (verbal memory, working memory, and processing speed or theory of mind). Despite the absence of objective differences, mothers self-reported significantly worse subjective memory than non-mothers. To interpret the difference between objective and subjective measures of memory, we investigated relationships between subjective memory, objective memory, and wellbeing. Mothers, but not non-mothers, showed a positive correlation between subjective and objective measures of memory, indicating mothers are "in-tune" with their memory performance. Mothers also demonstrated a positive relationship between subjective memory and wellbeing (sleep, anxiety, and depression), where better wellbeing correlated with higher subjective memory. This relationship was not apparent in non-mothers. The results suggest that poorer sleep, higher anxiety, and higher depression are related to reports of poorer self-reported memory in mothers. Conclusion: Our results add to our growing understanding of maternal cognition at 1 year postpartum, with no evidence of cognitive differences between mothers and non-mothers.


Assuntos
Transtornos Cognitivos , Ansiedade/psicologia , Cognição , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/psicologia , Feminino , Humanos , Memória , Período Pós-Parto/psicologia
12.
Neuroimage ; 262: 119581, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-35995375

RESUMO

Active navigation seems to yield better spatial knowledge than passive navigation, but it is unclear how active decision-making influences learning and memory. Here, we examined the contributions of theta oscillations to memory-related exploration while testing theories about how they contribute to active learning. Using electroencephalography (EEG), we tested individuals on a maze-learning task in which they made discrete decisions about where to explore at each choice point in the maze. Half the participants were free to make active decisions at each choice point, and the other half passively explored by selecting a marked choice (matched to active exploration) at each intersection. Critically, all decisions were made when stationary, decoupling the active decision-making process from movement and speed factors, which is another prominent potential role for theta oscillations. Participants were then tested on their knowledge of the maze by traveling from object A to object B within the maze. Results show an advantage for active decision-making during learning and indicate that the active group had greater theta power during choice points in exploration, particularly in midfrontal channels. These findings demonstrate that active exploration is associated with theta oscillations during human spatial navigation, and that these oscillations are not exclusively related to movement or speed. Results demonstrating increased theta oscillations in prefrontal regions suggest communication with the hippocampus and integration of new information into memory. We also found evidence for alpha oscillations during active navigation, suggesting a role for attention as well. This study finds support for a general mnemonic role for theta oscillations during navigational learning.


Assuntos
Navegação Espacial , Hipocampo , Humanos , Aprendizagem em Labirinto , Memória , Ritmo Teta
13.
Neuropharmacology ; 218: 109215, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-35977628

RESUMO

We recently reported that the competitive NMDAR antagonist (R,S)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) does not suppress NMDAR-mediated field EPSPs (fEPSPNMDA) or long-term potentiation (LTP) in vitro at concentrations that block contextual conditioning in vivo. Here we tested one possible explanation for the mismatch - that the hippocampus is relatively resistant to CPP compared to other brain structures engaged in contextual fear conditioning. Using the context pre-exposure facilitation effect (CPFE) paradigm to separate the hippocampal and extra-hippocampal components of contextual learning, we found that the active enantiomer (R)-CPP suppressed the hippocampal component with an IC50 of 3.1 mg/kg, a dose that produces brain concentrations below those required to block fEPSPNMDA or LTP. Moreover, using in-vivo calcium imaging of place cells and spatial engrams to directly assess hippocampal spatial coding, we found that (R)-CPP dose-dependently reduced the development of place cells and interfered with the formation of stable spatial engrams when it was administered prior to exposing mice to a novel context. Both effects occurred at doses that interfered with freezing to context in CPFE experiments. We conclude that (R)-CPP blocks memory formation by interfering with hippocampal function, but that it does so by modulating NMDARs at sites that are not engaged in vitro in the same manner that they are in vivo - perhaps through interneuron circuits that do not contribute to fEPSPs and are not required to elicit LTP using standard induction protocols in vitro, but are essential for successful mnemonic function in vivo.


Assuntos
Células de Lugar , Animais , Hipocampo , Memória , Camundongos , N-Metilaspartato/farmacologia , Células de Lugar/metabolismo , Pirazinas , Receptores de N-Metil-D-Aspartato/metabolismo
14.
Transl Psychiatry ; 12(1): 354, 2022 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-36045119

RESUMO

Posttraumatic stress disorder (PTSD) is characterised by dysregulated hypothalamic-pituitary-adrenal axis activity and altered glucocorticoid receptor sensitivity. Early treatment with glucocorticoids may reduce PTSD risk, although the effect of such treatment on the aetiologically critical step of traumatic-memory-formation remains unclear. Here we examine the effects of exogenous cortisol (hydrocortisone) in a preclinical model of PTSD, using a factorial (Drug × Sex), randomised-controlled, double-blind design. Healthy men and women (n = 120) were randomised to receive 30 mg oral hydrocortisone or matched placebo immediately after watching a stressful film. Effects on film-related intrusions were assessed acutely in the lab, and ecologically using daily memory diaries for one week. We found that participants receiving hydrocortisone showed a faster reduction in daily intrusion frequency. Voluntary memory was assessed once, at the end of the week, but was unaffected by hydrocortisone. Exploratory analyses indicated sex-dependent associations between intrusions and baseline estradiol and progesterone levels. In men receiving hydrocortisone, higher baseline estradiol levels were associated with fewer intrusions, whereas women exhibited the opposite pattern. By contrast, progesterone levels were positively associated with intrusions only in men treated with hydrocortisone. The findings suggest that hydrocortisone promotes an accelerated degradation of sensory-perceptual representations underlying traumatic intrusive memories. In addition, while sex alone was not an important moderator, the combination of sex and sex-hormone levels (especially estradiol) influenced hydrocortisone's effects on involuntary aversive memories. Future well-powered experimental studies may provide a basis for a precision-psychiatry approach to optimising early post-traumatic glucocorticoid treatments that target intrusive memories, based on individual endocrinological profiles.


Assuntos
Hidrocortisona , Transtornos de Estresse Pós-Traumáticos , Estradiol/farmacologia , Feminino , Humanos , Hidrocortisona/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Masculino , Memória , Sistema Hipófise-Suprarrenal/metabolismo , Progesterona/farmacologia , Transtornos de Estresse Pós-Traumáticos/tratamento farmacológico
15.
Behav Res Ther ; 157: 104167, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35963181

RESUMO

We investigated if improving a patient's memory for the content of their treatment, via the Memory Support Intervention, improves illness course and functional outcomes. The platform for investigating this question was major depressive disorder (MDD) and cognitive therapy (CT). Adults diagnosed with MDD (N = 178) were randomly allocated to CT + Memory Support (n = 91) or CT-as-usual (n = 87). Both treatments were comprised of 20-26, 50-min sessions over 16 weeks. Blind assessments were conducted before and immediately following treatment (post-treatment) and 6 months later (6FU). Patient memory for treatment, assessed with a free recall task, was higher in CT + Memory Support for past session recall at post-treatment. Both treatment arms were associated with reductions in depressive symptoms and functional impairment except: CT + Memory Support exhibited lower depression severity at 6FU (b = -3.09, p = 0.050, d = -0.27), and greater reduction in unhealthy days from baseline to 6FU (b = -4.21, p = 0.010, d = -1.07), compared to CT-as-usual. While differences in illness course and functional outcomes between the two treatment arms were limited, it is possible that future analyses of the type of memory supports and longer follow-up may yield more encouraging outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT01790919. Registered October 6, 2016.


Assuntos
Terapia Cognitivo-Comportamental , Transtorno Depressivo Maior , Adulto , Depressão/terapia , Transtorno Depressivo Maior/psicologia , Humanos , Memória , Resultado do Tratamento
16.
Elife ; 112022 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-35993533

RESUMO

Replay, the sequential reactivation within a neuronal ensemble, is a central hippocampal mechanism postulated to drive memory processing. While both rate and place representations are used by hippocampal place cells to encode behavioral episodes, replay has been largely defined by only the latter - based on the fidelity of sequential activity across neighboring place fields. Here, we show that dorsal CA1 place cells in rats can modulate their firing rate between replay events of two different contexts. This experience-dependent phenomenon mirrors the same pattern of rate modulation observed during behavior and can be used independently from place information within replay sequences to discriminate between contexts. Our results reveal the existence of two complementary neural representations available for memory processes.


How do our brains store memories? We now know that this is a complex and dynamic process, involving multiple regions of the brain. A brain region, called the hippocampus, plays an important role in memory formation. While we sleep, the hippocampus works to consolidate information, and eventually creates stable, long-term memories that are then stored in other parts of the brain. But how does the hippocampus do this? Neuroscientists believe that it can replay the patterns of brain activity that represent particular memories. By repeatedly doing this while we sleep, the hippocampus can then direct the transfer of this information to the rest of the brain for storage. The behaviour of nerve cells in the brain underpins these patterns of brain activity. When a nerve cell is active, it fires tiny electrical impulses that can be detected experimentally. The brain thus represents information in two ways: which nerve cells are active and when (sequential patterns); and how active the nerve cells are (how fast they fire electrical impulses or firing rate). For example, when an animal moves from one location to another, special place cells in the hippocampus become active in a distinct sequence. Depending on the context, they will also fire faster or slower. We know that the hippocampus can replay sequential patterns of nerve cell activity during memory consolidation, but whether it can also replay the firing rates associated with a particular experience is still unknown. Tirole, Huelin Gorriz et al. set out to determine if the hippocampus could also preserve the information encoded by firing rate during replay. In the experiments, rats explored two different environments that they had not seen before. The activity of the rats' place cells was recorded before and after they explored, and also later while they were sleeping. Analysis of the recordings revealed that during replay, the rats' hippocampi could indeed reproduce both the sequential patterns of activity and the firing rate of the place cells. It also confirmed that each environment was associated with unique firing rates ­ in other words, the firing rates were memory-specific. These results contribute to our understanding of how the hippocampus represents and processes information about our experiences. More broadly, they also shed new light on how the brain lays down memories, by revealing a key part of the mechanism that it uses to consolidate that information.


Assuntos
Hipocampo , Células de Lugar , Animais , Hipocampo/fisiologia , Memória/fisiologia , Neurônios/fisiologia , Células de Lugar/fisiologia , Ratos
17.
Hippocampus ; 32(10): 765-775, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36000813

RESUMO

Growth factors, such as insulin-like growth factor 1 (IGF-1), among others are known for their critical involvement in learning and memory processes. IGF-1 regulates cognitive functions, synapse density, neurotransmission, and adult neurogenesis and induces structural and synaptic plasticity-specific changes. Although IGF-1 has been suggested to participate in different memory processes, its role in memories associated with negative emotional experiences still remains to be elucidated. The principal aim of the present study was to test whether IGF-1 overexpression using adenoviral vectors in basolateral amygdala (BLA) influences both the expression and formation of contextual fear memory, as well as the hippocampal structural plasticity associated with such memory trace. We found that IGF-1 overexpression promotes the formation and expression of a specific contextual fear memory trace, and such effect persisted at least 7 days after recall. Moreover, the overexpression of this growth factor in BLA upregulates the activation of the ERK/MAPK pathway in this brain structure. In addition, intra-BLA IGF-1 overexpression causes dorsal hippocampus (DH) structural plasticity modifications promoting changes in the proportion of mature dendritic spines in the CA1 region, after a weak conditioning protocol. The present findings contribute to the knowledge underlying BLA-DH trace memory of fear and reveal important new insights into the neurobiology and neurochemistry of fear acquisition modulated by IGF-1 overexpression. The understanding of how IGF-1 modulates the formation of a fear contextual trace may pave the way for the development of novel therapeutic strategies focused on fear, anxiety, and trauma-related disorders.


Assuntos
Complexo Nuclear Basolateral da Amígdala , Complexo Nuclear Basolateral da Amígdala/fisiologia , Medo/fisiologia , Hipocampo/fisiologia , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Memória/fisiologia
18.
Zoolog Sci ; 39(4)2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35960033

RESUMO

Epicatechin (EpiC) enhances long-term memory (LTM) formation in the pond snail Lymnaea stagnalis. Here we investigated at the level of a single neuron, RPeD1, which is a necessary site for LTM formation of operant conditioning of aerial respiration, how EpiC may bring about its enhancing effect on LTM formation. When snails were operantly conditioned in EpiC (15 mg/l) by a single 0.5 h training session, which typically only results in memory lasting ∼3 h, they now formed LTM lasting at least 24 h. We recorded from RPeD1 in semi-intact preparations made from snails 24 h after a single 0.5 h training session in EpiC or pond water (PW) and found that the firing and bursting rate of RPeD1 decreased significantly in the EpiC preparations compared to the PW preparations. However, the excitability (i.e., number of spikes evoked by injected depolarizing current) of RPeD1 was not different between the two preparations. We next performed "in vitro" operant training in semi-intact preparations made from naïve snails. In the training, we applied a gentle tactile stimulus to the pneumostome area every time the semi-intact preparation began to open. The preparations exposed to EpiC-saline (15 mg/l) exhibited significantly increased RPeD1 excitability compared with saline only preparations. These results suggest that EpiC can alter some electrophysiological properties of a neuron that is a necessary site for learning and memory formation.


Assuntos
Catequina , Lymnaea , Animais , Lymnaea/fisiologia , Memória/fisiologia , Memória de Longo Prazo/fisiologia , Neurônios/fisiologia , Caramujos
19.
Mol Brain ; 15(1): 74, 2022 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-36038926

RESUMO

Accumulating evidence has shown that intestinal inflammations in inflammatory bowel disease (IBD) also drive pathological responses in organs outside the intestine, including the brain. Previous studies using the dextran sodium sulfate (DSS)-induced colitis model have shown that colonic inflammation contributes to the development of anxiety- and depression-related behaviors; however, little is known about whether memory function is affected. Here, we subjected male and female C57BL/6J mice to DSS-induced colitis for 6 days, followed by Pavlovian conditioned fear (CF) tests 15 days after the start of inflammation, when local colonic inflammation has receded. The contextual and cued CF tests were used to assess associative fear memory. We found that DSS-induced colitis led to significant impairment in contextual fear memory in both male and female mice; on the other hand, auditory cued fear memories were comparable between control and DSS-treated mice. There were marked signs of astrogliosis in the hippocampal regions 17 days (D17) after colitis induction. Furthermore, molecular characterization of hippocampi showed marked but transient increases in the expression of inflammatory genes Nfkb, Trem2 (microglial marker), GFAP (astrocyte marker), Il1b, and S100a8 in DSS-treated mice. While the expression of Nfkb, Trem2, and GFAP showed a peak on day 10, the S100a8 expression was high on days 10 and 17 and subsided on day 42. Interestingly, expression of Bdnf remained elevated in the times assessed (D10, 17, 42). Together, these results demonstrated that DSS-induced colitis could induce prolonged neuroinflammation and impaired contextual fear memory.


Assuntos
Colite , Animais , Colite/complicações , Colo/patologia , Sulfato de Dextrana , Modelos Animais de Doenças , Medo , Feminino , Inflamação/patologia , Masculino , Glicoproteínas de Membrana , Memória , Camundongos , Camundongos Endogâmicos C57BL , NF-kappa B , Receptores Imunológicos
20.
PLoS One ; 17(8): e0272427, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35917361

RESUMO

Errorful learning suggests that, when perfect learning has not yet been attained, errors can enhance future learning if followed by corrective feedback. Research on memory updating has shown that after retrieval, memory becomes more malleable and prone to change. Thus, retrieval of a wrong answer might provide a good context for the incorporation of feedback. Here, we tested this hypothesis using sentences including pragmatic sentence implications, commonly used for the study of false memories. Across two experiments with young adults, we hypothesized that corrective feedback would be more efficient at reducing false memories if provided immediately after retrieval, when memory is more malleable than after being exposed to the material. Participants' memory was assessed as a function of the type of learning task (Experiment 1: retrieval vs. restudy; and Experiment 2: active vs. passive recognition); and whether participants received corrective feedback or not. In both experiments, we observed that retrieval not only improved correct recall (replicating the testing effect) but also promoted the correction of false memories. Notably, corrective feedback was more effective when given after errors that were committed during retrieval rather than after restudy (Experiment 1) or after passive recognition (Experiment 2). Our results suggest that the benefits of retrieval go beyond the testing effect since it also facilitates false memories correction. Retrieval seems to enhance memory malleability, thus improving the incorporation of feedback, compared to the mere presentation of the information. Our results support the use of learning strategies that engage in active and explicit retrieval because, even if the retrieved information is wrong-when immediate feedback is provided-memory updating is promoted and errors are more likely to be corrected.


Assuntos
Memória , Rememoração Mental , Retroalimentação , Retroalimentação Psicológica , Humanos , Reconhecimento Psicológico , Adulto Jovem
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