Search results for " CONSOLIDATION"

Hippocampal electrical stimulation disrupts associative learning when targeted at dentate spikes

2017

KEY POINTS Dentate spikes are fast fluctuations of hilar local-field potentials that take place during rest and are thought to reflect input arriving from the entorhinal cortex to the hippocampus. During dentate spikes, neuronal firing in hippocampal input (dentate gyrus) and output (CA1/CA3) regions is uncoupled. To date, the behavioural significance of dentate spikes is unknown. Here, we provide evidence that disrupting the dentate spike-related uncoupling of the dentate gyrus and the CA1/CA3 subregions for 1 h after training retards associative learning. We suggest dentate spikes play a significant role in memory consolidation. ABSTRACT Hippocampal electrophysiological oscillations, name…

2019

Traumatic brain injury (TBI) can lead to impaired cognition and memory consolidation. The acute phase (24–48 h) after TBI is often characterized by neural dysfunction in the vicinity of the lesion, but also in remote areas like the contralateral hemisphere. Protein homeostasis is crucial for synaptic long-term plasticity including the protein degradation systems, proteasome and autophagy. Still, little is known about the acute effects of TBI on synaptic long-term plasticity and protein degradation. Thus, we investigated TBI in a controlled cortical impact (CCI) model in the motor and somatosensory cortex of mice ex vivo-in vitro. Late long-term potentiation (l-LTP) was induced by theta-burs…

Mechanisms Underlying Memory Consolidation by Adult-Born Neurons During Sleep

2020

The mammalian hippocampus generates new neurons that incorporate into existing neuronal networks throughout the lifespan, which bestows a unique form of cellular plasticity to the memory system. Recently, we found that hippocampal adult-born neurons (ABNs) that were active during learning reactivate during subsequent rapid eye movement (REM) sleep and provided causal evidence that ABN activity during REM sleep is necessary for memory consolidation. Here, we describe the potential underlying mechanisms by highlighting distinct characteristics of ABNs including decoupled firing from local oscillations and ability to undergo profound synaptic remodeling in response to experience. We further di…

A competing risks tale on successful and unsuccessful fiscal consolidations

2019

Abstract This paper analyses the transitions out of fiscal consolidations using annual data for 17 industrial countries over the period 1975-2013 and applying a discrete-time competing risks duration model. Our approach allows us to distinguish the factors behind a successful or an unsuccessful end of fiscal consolidation episodes. The results show that economic and political factors, the size and typology of fiscal adjustments and the occurrence of crises explain the differences in the length and the success/failure of fiscal consolidations. Moreover, while fiscal adjustment programmes that end successfully display positive duration dependence, those that end in an unsuccessful manner are …

Acute effects of fluoxetine on inhibitory avoidance consolidation in male and female OF1 mice

2001

The effects of acute administration of fluoxetine on memory consolidation using an inhibitory avoidance task were investigated in male and female OF1 mice. Several doses of this antidepressant (5, 10, and 20 mg/kg) were intraperitoneally administered immediately after the training session. The test session was carried out four days later and response latencies were measured in both sessions. The results showed that the highest dose of fluoxetine significantly increased response latencies of inhibitory avoidance compared with the lowest dose and the control group. Sex differences in this task were observed, females showing a better performance. But the drug's effects were not sexually dimorp…

Negative emotional state modulates visual working memory in the late consolidation phase

2020

Although a considerable literature has grown up around the interactions between emotional state and visual working memory (VWM) performance, the mechanism underlying the impact of the negative emotional state on VWM remains unclear. The present study aimed to test whether the influence of emotional state is related to the early phase or late phase of VWM consolidation process. Across three experiments, we found that the negative emotional state did not affect VWM performance when the presentation time of stimuli was short. However, when the presentation time was long, the negative emotional state increased the VWM precision and reduced the VWM number. According to the two-phase model propos…

The Bandwidth of VWM Consolidation Varies With the Stimulus Feature: Evidence From Event-Related Potentials

2018

Our previous work suggests that 2 colors can be consolidated into visual short-term memory (VSTM) in parallel without a loss of memory precision, whereas consolidation of 2 orientations is performed in a strictly serial manner. Those experiments compared VSTM performance for simultaneously and sequentially presented stimuli. However, there is still controversy about whether the bandwidth for consolidation is determined by the type of information. To further investigate this issue, here we measured electroencephalography while participants attempted to consolidate 1, 2 or 4 simultaneously presented colors (Experiment 1) or orientations (Experiment 2) under limited presentation times. We used…

Effects of post-extinction l-DOPA administration on the spontaneous recovery and reinstatement of fear in a human fMRI study

2015

Relapse is a pertinent problem in the treatment of anxiety disorders. In the laboratory, relapse is modeled as return of conditioned fear responses after successful fear extinction and is explained by insufficient retrieval and/or expression of the fear-inhibitory extinction memory that is generated during extinction learning. We have shown in mice and humans that return of fear can be prevented by administration of a single dose of the dopamine precursor l-3,4-dihydroxyphenylalanine (l-DOPA) immediately after extinction. In mice, this effect could be attributed to an enhancement of extinction memory consolidation. In our human study, we could not exclude that l-DOPA might have acted by int…

Disvelare e conservare il palinsesto architettonico: il restauro del fronte chiaramontano nella corte interna del Collegio dei Santi Agostino e Tomma…

2020

La configurazione architettonica del Collegio dei SS. Agostino e Tommaso ad Agrigento è il risultato d’un plurisecolare processo di crescita per aggregazioni e revisioni intorno al nucleo fondativo trecentesco. La sua corte interna viene dunque a definirsi attraverso un percorso evolutivo di tipo processuale ed uno dei suoi lati mostra le tracce dell’originario palazzo Chiaramonte. Il contributo intende presentare una sintesi delle riflessioni che hanno condotto alla definizione del progetto di restauro, le matrici culturali che lo sostengono, le fasi dello studio analitico dei materiali e gli aspetti salienti del cantiere d’intervento, con particolare attenzione alla conservazione del fron…

Characterization of friction stir consolidated recycled billet by uniaxial compression tests with miniaturized cylindrical specimen

2023

Abstract. Friction stir consolidation (FSC) is a solid-state recycling method that directly converts machining scraps into semifinished billets. This process has been proven to be a more energy efficient and environmentally friendly technique compared to remelting based conventional recycling methods. During FSC, machining chips are transformed into a solid billet by the stirring action and friction heat of the rotating tool. Due to process mechanics, especially temperature gradient and strain rate, billets have shown different hardness values and grain size distribution across their sections. Therefore, in this research, miniaturized upsetting samples are extracted from the FSC billet. The…