A reward effect on memory retention, consolidation, and generalization?

Reward improves memory through both encoding and consolidation processes. In this preregistered study, we tested whether reward effects on memory generalize from high-rewarded items to low-rewarded but episodically related items. Fifty-nine human volunteers incidentally encoded associations between unique objects and repeated scenes. Some scenes typically yielded high reward, whereas others typically yielded low reward. Memory was tested immediately after encoding (n = 29) or the next day (n = 30). Overall, reward had only a limited influence on memory. It did not enhance consolidation and its effect did not generalize to episodically related stimuli. We thus contribute to understanding the boundary conditions of reward effects on memory.

The first balloon-borne sample analysis of atmospheric carbonaceous components reveals new insights into formation processes.

Atmospheric aerosol optical, physical, and chemical properties play a fundamental role in the Earth's climate system. A better understanding of the processes involved in their formation, evolution, and interaction with radiation and the water cycle is critical. We report the analysis of atmospheric molecules/particles collected with a new sampling system that flew under regular weather balloons for the first time. The flight took place on January 18, 2022 from Reims (France). The samples were subsequently analyzed by high-resolution mass spectrometry (Orbitrap) to specifically infer hundreds of organic components present in 4 different layers from the troposphere to the stratosphere (up to 20 km). Additional measurements of O3, CO, and aerosol concentrations a few hours before this flight took place to contextualize the sampling. After separating common species found on each filter that might be common to atmospheric layers or residuals for contaminations, we found that each sample yields significant differences in the number and size of organic species detected that should reflect the unique composition of atmospheric layers. While tropospheric samples yield significantly oxidized and saturated components, with carbon numbers below 30 that might be explained by complex organics chemistry from local and distant source emissions, the upper tropospheric and stratospheric samples were associated with increased carbon numbers (C > 30), with a significantly reduced unsaturation number for the stratosphere, that might be induced by strong UV radiations. The multimodal distributions of carbon numbers in chemical formulas observed between 15 and 20 km suggest that oligomerization and growth of organic molecules may take place in aged air masses of tropical origin that are known to carry organic compounds even several km above the tropopause where their lifetime significantly increases. In addition, the presence of organics may also reflect the extended influence of wildfires smoke injected during the spring and summer in the NH hemisphere before the in situ observations and their long-lifetime in the upper troposphere and stratosphere.

Characterization of the Autoxidation of Terpenes at Elevated Temperature Using High-Resolution Mass Spectrometry: Formation of Ketohydroperoxides and Highly Oxidized Products from Limonene.

Low-temperature experiments on the oxidation of limonene-O2-N2 mixtures were conducted in a jet-stirred reactor (JSR) over a range of temperatures (520-800 K) under fuel-lean conditions (equivalence ratio φ = 0.5) with a short residence time (1.5 s) and a pressure of 1 bar. Collected samples of the reaction mixtures were analyzed by (i) online Fourier transform infrared spectroscopy (FTIR) and (ii) Orbitrap Q-Exactive high-resolution mass spectrometry after direct injection or chromatographic separation using reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) and soft ionization (with positive or negative heated electrospray ionization and atmospheric-pressure chemical ionization). H/D exchange using deuterated water (D2O) and a reaction with 2,4-dinitrophenylhydrazine (2,4-DNPH) were performed to probe the presence of OH, OOH, and C═O groups in the oxidized products. A broad range of oxidation products ranging from water to highly oxygenated products containing five and more O atoms were detected (C7H10O4,5, C8H12O2,4, C8H14O2,4, C9H12O, C9H14O1,3-5, C10H12O2, C10H14O1-9, C10H16O2-5, and C10H18O6). Mass spectrometry analyses were only qualitative, and quantification was performed with FTIR. The results are discussed in terms of reaction routes involving the initial formation of peroxy radicals, H atom transfer, and O2 addition sequences producing a large set of chemical products, including ketohydroperoxides and more oxygenated products. Carbonyl compounds derived from the Waddington oxidation mechanism on exo- and endo-double bonds (C═C) were observed in addition to their products of further oxidation. Products of the Korcek mechanism (carboxylic acids and carbonyls) were also detected.

Simulation-based learning influences real-life attitudes.

Humans can vividly simulate hypothetical experiences. This ability draws on our memories (e.g., of familiar people and locations) to construct imaginings that resemble real-life events (e.g., of meeting a person at a location). Here, we examine the hypothesis that we also learn from such simulated episodes much like from actual experiences. Specifically, we show that the mere simulation of meeting a familiar person (unconditioned stimulus; US) at a known location (conditioned stimulus; CS) changes how people value the location. We provide key evidence that this simulation-based learning strengthens pre-existing CS-US associations and that it leads to a transfer of valence from the US to the CS. The data thus highlight a mechanism by which we learn from simulated experiences.

Suppression weakens unwanted memories via a sustained reduction of neural reactivation.

Aversive events sometimes turn into intrusive memories. However, prior evidence indicates that such memories can be controlled via a mechanism of retrieval suppression. Here, we test the hypothesis that suppression exerts a sustained influence on memories by deteriorating their neural representations. This deterioration, in turn, would hinder their subsequent reactivation and thus impoverish the vividness with which they can be recalled. In an fMRI study, participants repeatedly suppressed memories of aversive scenes. As predicted, this process rendered the memories less vivid. Using a pattern classifier, we observed that suppression diminished the neural reactivation of scene information both globally across the brain and locally in the parahippocampal cortices. Moreover, the decline in vividness was associated with reduced reinstatement of unique memory representations in right parahippocampal cortex. These results support the hypothesis that suppression weakens memories by causing a sustained reduction in the potential to reactivate their neural representations.

Promoting farsighted decisions via episodic future thinking: A meta-analysis.

Episodic future thinking (EFT) denotes our capacity to imagine prospective events. It has been suggested to promote farsighted decisions that entail a trade-off between short-term versus long-term gains. Here, we meta-analyze the evidence for the impact of EFT on such intertemporal choices that have monetary or health-relevant consequences. Across 174 effect sizes from 48 articles, a three-level model yielded a medium-sized effect of g = .44, 95% (CI) [.33, .55]. Notably, this analysis included a substantial number of unpublished experiments, and the effect remained significant following further adjustments for remaining publication bias. We exploited the observed heterogeneity to determine critical core components that moderate the impact of EFT. Specifically, the effect was stronger when the imagined events were positive, more vivid, and related to the delayed choice. We further obtained evidence for the contribution of the episodicity and future-orientedness of EFT. These results indicate that the impact of EFT cannot simply be accounted for by other modes of prospection (e.g., semantic future thinking). Of note, EFT had a greater impact in samples characterized by choice impulsivity (e.g., in obesity), suggesting that EFT can ameliorate maladaptive decision making. It may accordingly constitute a beneficial intervention for individuals who tend to make myopic decisions. Our analyses moreover indicated that the effect is unlikely to merely reflect demand characteristics. This meta-analysis highlights the potential of EFT in promoting long-term goals, a finding that extends from the laboratory to real-life decisions. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Towards a Comprehensive Characterization of the Low-Temperature Autoxidation of Di-n-Butyl Ether.

In the present study, we investigated the oxidation of 2500 ppm of di-n-butyl ether under fuel-rich conditions (φ = 2) at low temperatures (460-780 K), a residence time of 1 s, and 10 atm. The experiments were carried out in a fused silica jet-stirred reactor. Oxidation products were identified and quantified in gas samples by gas chromatography and Fourier transform infrared spectrometry. Samples were also trapped through bubbling in cool acetonitrile for high-pressure liquid chromatography (HPLC) analyses. 2,4-dinitro-phenylhydrazine was used to derivatize carbonyl products and distinguish them from other isomers. HPLC coupled to high resolution mass spectrometry (Orbitrap Q-Exactive®) allowed for the detection of oxygenated species never observed before, i.e., low-temperature oxidation products (C8H12O4,6, C8H16O3,5,7, and C8H18O2,5) and species that are more specific products of atmospheric oxidation, i.e., C16H34O4, C11H24O3, C11H22O3, and C10H22O3. Flow injection analyses indicated the presence of high molecular weight oxygenated products (m/z > 550). These results highlight the strong similitude in terms of classes of oxidation products of combustion and atmospheric oxidation, and through autoxidation processes. A kinetic modeling of the present experiments indicated some discrepancies with the present data.

Memory suppression and its deficiency in psychological disorders: A focused meta-analysis.

It is still debated whether suppressing the retrieval of unwanted memories causes forgetting and whether this constitutes a beneficial mechanism. To shed light on these 2 questions, we scrutinize the evidence for such suppression-induced forgetting (SIF) and examine whether it is deficient in psychological disorders characterized by intrusive thoughts. Specifically, we performed a focused meta-analysis of studies that have used the think/no-think procedure to test SIF in individuals either affected by psychological disorders or exhibiting high scores on related traits. Overall, across 96 effects from 25 studies, we found that avoiding retrieval leads to significant forgetting in healthy individuals, with a small to moderate effect size (0.28, 95% CI [0.14, 0.43]). Importantly, this effect was indeed larger than for more anxious (-0.21, 95% CI [-0.41, -0.02]) or depressed individuals (0.05, 95% CI [-0.19, 0.29])-though estimates for the healthy may be inflated by publication bias. In contrast, individuals with a stronger repressive coping style showed greater SIF (0.42, 95% CI [0.32, 0.52]). Furthermore, moderator analyses revealed that SIF varied with the exact suppression mechanism that participants were instructed to engage. For healthy individuals, the effect sizes were considerably larger when instructions induced specific mechanisms of direct retrieval suppression or thought substitution than when they were unspecific. These results suggest that intact suppression-induced forgetting is a hallmark of psychological well-being, and that inducing more specific suppression mechanisms fosters voluntary forgetting. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Variability in the analysis of a single neuroimaging dataset by many teams.

Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses1. The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset2-5. Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed.

Forming attitudes via neural activity supporting affective episodic simulations.

Humans have the adaptive capacity for imagining hypothetical episodes. Such episodic simulation is based on a neural network that includes the ventromedial prefrontal cortex (vmPFC). This network draws on existing knowledge (e.g., of familiar people and places) to construct imaginary events (e.g., meeting with the person at that place). Here, we test the hypothesis that a simulation changes attitudes towards its constituent elements. In two experiments, we demonstrate how imagining meeting liked versus disliked people (unconditioned stimuli, UCS) at initially neutral places (conditioned stimuli, CS) changes the value of these places. We further provide evidence that the vmPFC codes for representations of those elements (i.e., of individual people and places). Critically, attitude changes induced by the liked UCS are based on a transfer of positive affective value between the representations (i.e., from the UCS to the CS). Thereby, we reveal how mere imaginings shape attitudes towards elements (i.e., places) from our real-life environment.

An adaptive function of mental time travel: Motivating farsighted decisions.

The episodic memory system allows us to experience the emotions of past, counterfactual, and prospective events. We outline how this phenomenological experience can convey motivational incentives for farsighted decisions. In this way, we challenge important arguments for Mahr & Csibra's (M&C's) conclusion that future-oriented mental time travel is unlikely to be a central function of episodic memory.

Phosphonate-Mediated Immobilization of Rhodium/Bipyridine Hydrogenation Catalysts.

RhL2 complexes of phosphonate-derivatized 2,2'-bipyridine (bpy) ligands L were immobilized on titanium oxide particles generated in situ. Depending on the structure of the bipy ligand-number of tethers (1 or 2) to which the phosphonate end groups are attached and their location on the 2,2'-bipyridine backbone (4,4'-, 5,5'-, or 6,6'-positions)-the resulting supported catalysts showed comparable chemoselectivity but different kinetics for the hydrogenation of 6-methyl-5-hepten-2-one under hydrogen pressure. Characterization of the six supported catalysts suggested that the intrinsic geometry of each of the phosphonate-derivatized 2,2'-bipyridines leads to supported catalysts with different microstructures and different arrangements of the RhL2 species at the surface of the solid, which thereby affect their reactivity.

Increased hippocampus to ventromedial prefrontal connectivity during the construction of episodic future events.

Both the hippocampus and ventromedial prefrontal cortex (vmPFC) appear to be critical for episodic future simulation. Damage to either structure affects one's ability to remember the past and imagine the future, and both structures are commonly activated as part of a wider core network during future simulation. However, the precise role played by each of these structures and, indeed, the direction of information flow between them during episodic simulation, is still not well understood. In this study, we scanned participants using functional magnetic resonance imaging while they imagined future events in response to object cues. We then used dynamic causal modeling to examine effective connectivity between the left anterior hippocampus and vmPFC during the initial mental construction of the events. Our results show that while there is strong bidirectional intrinsic connectivity between these regions (i.e., irrespective of task conditions), only the hippocampus to vmPFC connection increases during the construction of episodic future events, suggesting that the hippocampus initiates event simulation in response to retrieval cues, driving activation in the vmPFC where episodic details may be further integrated.

Episodic Future Thinking: Mechanisms and Functions.

Episodic future thinking refers to the capacity to imagine or simulate experiences that might occur in one's personal future. Cognitive, neuropsychological, and neuroimaging research concerning episodic future thinking has accelerated during recent years. This article discusses research that has delineated cognitive and neural mechanisms that support episodic future thinking as well as the functions that episodic future thinking serves. Studies focused on mechanisms have identified a core brain network that underlies episodic future thinking and have begun to tease apart the relative contributions of particular regions in this network, and the specific cognitive processes that they support. Studies concerned with functions have identified several domains in which episodic future thinking produces performance benefits, including decision making, emotion regulation, prospective memory, and spatial navigation.

Characterizing the role of the hippocampus during episodic simulation and encoding.

The hippocampus has been consistently associated with episodic simulation (i.e., the mental construction of a possible future episode). In a recent study, we identified an anterior-posterior temporal dissociation within the hippocampus during simulation. Specifically, transient simulation-related activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. In line with previous theoretical proposals of hippocampal function during simulation, the posterior hippocampal activity was interpreted as reflecting a transient retrieval process for the episodic details necessary to construct an episode. In contrast, the sustained anterior hippocampal activity was interpreted as reflecting the continual recruitment of encoding and/or relational processing associated with a simulation. In the present study, we provide a direct test of these interpretations by conducting a subsequent memory analysis of our previously published data to assess whether successful encoding during episodic simulation is associated with the anterior hippocampus. Analyses revealed a subsequent memory effect (i.e., later remembered > later forgotten simulations) in the anterior hippocampus. The subsequent memory effect was transient and not sustained. Taken together, the current findings provide further support for a component process model of hippocampal function during simulation. That is, unique regions of the hippocampus support dissociable processes during simulation, which include the transient retrieval of episodic information, the sustained binding of such information into a coherent episode, and the transient encoding of that episode for later retrieval.

Priming, not inhibition, of related concepts during future imagining.

Remembering the past and imagining the future both involve the retrieval of details stored in episodic memory and rely on the same core network of brain regions. Given these parallels, one might expect similar component processes to be involved in remembering and imagining. While a strong case can be made for the role of inhibition in memory retrieval, few studies have examined whether inhibition is also necessary for future imagining and results to-date have been mixed. In the current study, we test whether related concepts are inhibited during future imagining using a modified priming approach. Participants first generated a list of familiar places and for each place, the people they most strongly associate with it. A week later, participants imagined future events involving recombinations of people and places, immediately followed by a speeded response task in which participants made familiarity decisions about people's names. Across two experiments, our results suggest that related concepts are not inhibited during future imagining, but rather are automatically primed. These results fit with recent work showing that autobiographically significant concepts (e.g., friends' names) are more episodic than semantic in nature, automatically activating related details in memory and potentially fuelling the flexible simulation of future events.

Imagining the future: The core episodic simulation network dissociates as a function of timecourse and the amount of simulated information.

Neuroimaging data indicate that episodic memory (i.e., remembering specific past experiences) and episodic simulation (i.e., imagining specific future experiences) are associated with enhanced activity in a common set of neural regions, often referred to as the core network. This network comprises the hippocampus, parahippocampal cortex, lateral and medial parietal cortex, lateral temporal cortex, and medial prefrontal cortex. Evidence for a core network has been taken as support for the idea that episodic memory and episodic simulation are supported by common processes. Much remains to be learned about how specific core network regions contribute to specific aspects of episodic simulation. Prior neuroimaging studies of episodic memory indicate that certain regions within the core network are differentially sensitive to the amount of information recollected (e.g., the left lateral parietal cortex). In addition, certain core network regions dissociate as a function of their timecourse of engagement during episodic memory (e.g., transient activity in the posterior hippocampus and sustained activity in the left lateral parietal cortex). In the current study, we assessed whether similar dissociations could be observed during episodic simulation. We found that the left lateral parietal cortex modulates as a function of the amount of simulated details. Of particular interest, while the hippocampus was insensitive to the amount of simulated details, we observed a temporal dissociation within the hippocampus: transient activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. Because the posterior hippocampal and lateral parietal findings parallel those observed during episodic memory, the present results add to the evidence that episodic memory and episodic simulation are supported by common processes. Critically, the present study also provides evidence that regions within the core network support dissociable processes.

Reducing future fears by suppressing the brain mechanisms underlying episodic simulation.

Imagining future events conveys adaptive benefits, yet recurrent simulations of feared situations may help to maintain anxiety. In two studies, we tested the hypothesis that people can attenuate future fears by suppressing anticipatory simulations of dreaded events. Participants repeatedly imagined upsetting episodes that they feared might happen to them and suppressed imaginings of other such events. Suppressing imagination engaged the right dorsolateral prefrontal cortex, which modulated activation in the hippocampus and in the ventromedial prefrontal cortex (vmPFC). Consistent with the role of the vmPFC in providing access to details that are typical for an event, stronger inhibition of this region was associated with greater forgetting of such details. Suppression further hindered participants' ability to later freely envision suppressed episodes. Critically, it also reduced feelings of apprehensiveness about the feared scenario, and individuals who were particularly successful at down-regulating fears were also less trait-anxious. Attenuating apprehensiveness by suppressing simulations of feared events may thus be an effective coping strategy, suggesting that a deficiency in this mechanism could contribute to the development of anxiety.

Comparison of Zirconium Phosphonate-Modified Surfaces for Immobilizing Phosphopeptides and Phosphate-Tagged Proteins.

Different routes for preparing zirconium phosphonate-modified surfaces for immobilizing biomolecular probes are compared. Two chemical-modification approaches were explored to form self-assembled monolayers on commercially available primary amine-functionalized slides, and the resulting surfaces were compared to well-characterized zirconium phosphonate monolayer-modified supports prepared using Langmuir-Blodgett methods. When using POCl3 as the amine phosphorylating agent followed by treatment with zirconyl chloride, the result was not a zirconium-phosphonate monolayer, as commonly assumed in the literature, but rather the process gives adsorbed zirconium oxide/hydroxide species and to a lower extent adsorbed zirconium phosphate and/or phosphonate. Reactions giving rise to these products were modeled in homogeneous-phase studies. Nevertheless, each of the three modified surfaces effectively immobilized phosphopeptides and phosphopeptide tags fused to an affinity protein. Unexpectedly, the zirconium oxide/hydroxide modified surface, formed by treating the amine-coated slides with POCl3/Zr(4+), afforded better immobilization of the peptides and proteins and efficient capture of their targets.

Repetition-Related Reductions in Neural Activity during Emotional Simulations of Future Events.

Simulations of future experiences are often emotionally arousing, and the tendency to repeatedly simulate negative future outcomes has been identified as a predictor of the onset of symptoms of anxiety. Nonetheless, next to nothing is known about how the healthy human brain processes repeated simulations of emotional future events. In this study, we present a paradigm that can be used to study repeated simulations of the emotional future in a manner that overcomes phenomenological confounds between positive and negative events. The results show that pulvinar nucleus and orbitofrontal cortex respectively demonstrate selective reductions in neural activity in response to frequently as compared to infrequently repeated simulations of negative and positive future events. Implications for research on repeated simulations of the emotional future in both non-clinical and clinical populations are discussed.