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The hippocampus is considered essential for several forms of declarative memory, including spatial and social memory. Despite the extensive research of the classic subfields of the hippocampus, the fasciola cinerea (FC)—a medially located structure within the hippocampal formation—has remained largely unexplored. In the present study, we performed a morpho‐functional characterization of principal neurons in the mouse FC. Using in vivo juxtacellular recording of single neurons, we found that FC neurons are distinct from neighboring CA1 pyramidal cells, both morphologically and electrophysiologically. Specifically, FC neurons displayed non‐pyramidal morphology and granule cell‐like apical dendrites. Compared to neighboring CA1 pyramidal neurons, FC neurons exhibited more regular in vivo firing patterns and a lower tendency to fire spikes at short interspike intervals. Furthermore, tracing experiments revealed that the FC receives inputs from the lateral but not the medial entorhinal cortex and CA3, and it provides a major intra‐hippocampal projection to the septal CA2 and sparser inputs to the distal CA1. Overall, our results indicate that the FC is a morphologically and electrophysiologically distinct subfield of the hippocampal formation; given the established role of CA2 in social memory and seizure initiation, the unique efferent intra‐hippocampal connectivity of the FC points to possible roles in social cognition and temporal lobe epilepsy. [ABSTRACT FROM AUTHOR]

Studies of the impact of brain injury on memory processes often focus on the quantity and episodic richness of those recollections. Here, we argue that the organization of one's recollections offers critical insights into the impact of brain injury on functional memory. It is well‐established in studies of word list memory that free recall of unrelated words exhibits a clear temporal organization. This temporal contiguity effect refers to the fact that the order in which word lists are recalled reflects the original presentation order. Little is known, however, about the organization of recall for semantically rich materials, nor how recall organization is impacted by hippocampal damage and memory impairment. The present research is the first study, to our knowledge, of temporal organization in semantically rich narratives in three groups: (1) Adults with bilateral hippocampal damage and severe declarative memory impairment, (2) adults with bilateral ventromedial prefrontal cortex (vmPFC) damage and no memory impairment, and (3) demographically matched non‐brain‐injured comparison participants. We find that although the narrative recall of adults with bilateral hippocampal damage reflected the temporal order in which those narratives were experienced above chance levels, their temporal contiguity effect was significantly attenuated relative to comparison groups. In contrast, individuals with vmPFC damage did not differ from non‐brain‐injured comparison participants in temporal contiguity. This pattern of group differences yields insights into the cognitive and neural systems that support the use of temporal organization in recall. These data provide evidence that the retrieval of temporal context in narrative recall is hippocampal‐dependent, whereas damage to the vmPFC does not impair the temporal organization of narrative recall. This evidence of limited but demonstrable organization of memory in participants with hippocampal damage and amnesia speaks to the power of narrative structures in supporting meaningfully organized recall despite memory impairment. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Metabolic syndrome (MetS) has been linked to dementia. In this study, we examined the association of MetS with neuroimaging and cognition in dementia-free adults, offering insight into the impact of MetS on brain health prior to dementia onset. RESEARCH DESIGN AND METHODS: We included 37,395 dementia-free adults from the UK Biobank database. MetS was defined as having at least three of the following components: larger waist circumference; elevated levels of triglycerides, blood pressure, HbA1c; or reduced HDL cholesterol levels. Multivariable-adjusted linear regression was used to assess associations of MetS with structural neuroimaging and cognitive domains. RESULTS: MetS was associated with lower total brain (standardized β: −0.06; 95% CI −0.08, −0.04), gray matter (β: −0.10; 95% CI −0.12, −0.08) and hippocampal (for left side, β: −0.03, 95% CI −0.05, −0.01; for right side, β: −0.04, 95% CI −0.07, −0.02) volumes, and greater white matter hyperintensity (WMH) volume (β: 0.08; 95% CI 0.06, 0.11). Study participants with MetS performed poorer on cognitive tests of working memory (β: −0.10; 95% CI −0.13, −0.07), verbal declarative memory (β: −0.08; 95% CI −0.11, −0.05), processing speed (β: −0.06; 95% CI −0.09, −0.04), verbal and numerical reasoning (β: −0.07; 95% CI −0.09, −0.04), nonverbal reasoning (β: −0.03; 95% CI −0.05, −0.01), and on tests of executive function, where higher scores indicated poorer performance (β: 0.05; 95% CI 0.03, 0.08). More MetS components were also associated with less brain volume, greater WMH, and poorer cognition across all domains. CONCLUSIONS: MetS was associated poorer brain health in dementia-free adults, characterized by less brain volume, greater vascular pathology, and poorer cognition. Further research is necessary to understand whether reversal or improvement of MetS can improve brain health. [ABSTRACT FROM AUTHOR]

Summary: Acute exercise has been shown to affect long‐term memory and sleep. However, it is unclear whether exercise‐induced changes in sleep architecture are associated with enhanced memory. Recently, it has been shown that exercise followed by a nap improved declarative memory. Whether these effects transfer to night sleep and other memory domains has not yet been studied. Here, we investigate the influence of exercise on nocturnal sleep architecture and associations with sleep‐dependent procedural and declarative memory consolidation. Nineteen subjects (23.68 ± 3.97 years) were tested in a balanced cross‐over design. In two evening sessions, participants either exercised (high‐intensity interval training) or rested immediately after encoding two memory tasks: (1) a finger tapping task and (2) a paired‐associate learning task. Subsequent nocturnal sleep was recorded by polysomnography. Retrieval was conducted the following morning. High‐intensity interval training lead to an increased declarative memory retention (p = 0.047, d = 0.40) along with a decrease in REM sleep (p = 0.012, d = 0.75). Neither procedural memory nor NREM sleep were significantly affected. Exercise‐induced changes in N2 showed a positive correlation with procedural memory retention which did not withstand multiple comparison correction. Exploratory analyses on sleep spindles and slow wave activity did not reveal significant effects. The present findings suggest an exercise‐induced enhancement of declarative memory which aligns with changes in nocturnal sleep architecture. This gives additional support for the idea of a potential link between exercise‐induced sleep modifications and memory formation which requires further investigation in larger scaled studies. [ABSTRACT FROM AUTHOR]

The objective of image captioning models is to bridge the gap between the visual and linguistic modalities by generating natural language descriptions that accurately reflect the content of input images. In recent years, researchers have leveraged deep learning-based models and made advances in the extraction of visual features and the design of multimodal connections to tackle this task. This work presents a novel approach toward developing image captioning models that utilize an external kNN memory to improve the generation process. Specifically, we propose two model variants that incorporate a knowledge retriever component that is based on visual similarities, a differentiable encoder to represent input images, and a kNN-augmented language model to predict tokens based on contextual cues and text retrieved from the external memory. We experimentally validate our approach on COCO and nocaps datasets and demonstrate that incorporating an explicit external memory can significantly enhance the quality of captions, especially with a larger retrieval corpus. This work provides valuable insights into retrieval-augmented captioning models and opens up new avenues for improving image captioning at a larger scale. [ABSTRACT FROM AUTHOR]

Substantial progress has been made in understanding the neurocognitive underpinnings of learning math. Building on this work, it has been hypothesized that declarative and procedural memory, two domain-general learning and memory systems, play important roles in acquiring math skills. In a longitudinal study, we tested whether in fact declarative and procedural memory predict children's math skills during elementary school years. A sample of 109 children was tested across grades 2, 3 and 4. Linear mixed-effects regression and structural equation modeling revealed the following. First, learning in declarative but not procedural memory was associated with math skills within each grade. Second, declarative but not procedural memory in each grade was related to math skills in all later grades (e.g., declarative memory in grade 2 was related to math skills in grade 4). Sensitivity analyses showed that the pattern of results was robust, except for the longitudinal prediction of later math skills when accounting for stable inter-individual differences via the inclusion of random intercepts. Our findings highlight the foundational role of early domain-general learning and memory in children's acquisition of math. [ABSTRACT FROM AUTHOR]

In many domains, learners extract recurring units from continuous sequences. For example, in unknown languages, fluent speech is perceived as a continuous signal. Learners need to extract the underlying words from this continuous signal and then memorize them. One prominent candidate mechanism is statistical learning, whereby learners track how predictive syllables (or other items) are of one another. Syllables within the same word predict each other better than syllables straddling word boundaries. But does statistical learning lead to memories of the underlying words—or just to pairwise associations among syllables? Electrophysiological results provide the strongest evidence for the memory view. Electrophysiological responses can be time‐locked to statistical word boundaries (e.g., N400s) and show rhythmic activity with a periodicity of word durations. Here, I reproduce such results with a simple Hebbian network. When exposed to statistically structured syllable sequences (and when the underlying words are not excessively long), the network activation is rhythmic with the periodicity of a word duration and activation maxima on word‐final syllables. This is because word‐final syllables receive more excitation from earlier syllables with which they are associated than less predictable syllables that occur earlier in words. The network is also sensitive to information whose electrophysiological correlates were used to support the encoding of ordinal positions within words. Hebbian learning can thus explain rhythmic neural activity in statistical learning tasks without any memory representations of words. Learners might thus need to rely on cues beyond statistical associations to learn the words of their native language. Research Highlights: Statistical learning may be utilized to identify recurring units in continuous sequences (e.g., words in fluent speech) but may not generate explicit memory for words.Exposure to statistically structured sequences leads to rhythmic activity with a period of the duration of the underlying units (e.g., words).I show that a memory‐less Hebbian network model can reproduce this rhythmic neural activity as well as putative encodings of ordinal positions observed in earlier research.Direct tests are needed to establish whether statistical learning leads to declarative memories for words. [ABSTRACT FROM AUTHOR]

Theta oscillations support memory formation, but their exact contribution to the communication between prefrontal cortex (PFC) and the hippocampus is unknown. We tested the functional relevance of theta oscillations as a communication link between both areas for memory formation using transcranial alternating current stimulation (tACS). Healthy, young participants learned two lists of Dutch-German word pairs and retrieved them immediately and with a 30-min delay. In the encoding group (N = 30), tACS was applied during the encoding of list 1. List 2 was used to test stimulation aftereffects. In the retrieval group (N = 23), we stimulated during the delayed recall. In both groups, we applied tACS bilaterally at prefrontal and tempo-parietal sites, using either individualized theta frequency or 15 Hz (as control), according to a within-subject design. Stimulation with theta-tACS did not alter overall learning performance. An exploratory analysis revealed that immediate recall improved when word-pairs were learned after theta-tACS (list 2). Applying theta-tACS during retrieval had detrimental effects on memory. No changes in the power of the respective frequency bands were observed. Our results do not support the notion that impacting the communication between PFC and the hippocampus during a task by bilateral tACS improves memory. However, we do find evidence that direct stimulation had a trend for negatively interfering effects during immediate and delayed recall. Hints for beneficial effects on memory only occurred with aftereffects of the stimulation. Future studies need to further examine the effects during and after stimulation on memory formation. [ABSTRACT FROM AUTHOR]

In the wake of several traumatic experiences, a French woman in her early 50s began to have visions and intuitive impressions about seven past lives she felt she had lived. She was able to verify memories of the most recent life and identify the deceased, an American Marine fatally wounded in Vietnam. It then became clear that she had been subliminally influenced by this life in various ways from childhood, most strongly following an NDE at 18. On the eve of the Russian invasion of Ukraine, she began to have detailed visions of a Don Cossack who had served in the Imperial Guard of Catherine the Great and Alexander I, dying during Napoleon's retreat from Moscow in 1812. Although the Cossack story is plausible, it has not been possible to investigate it or to identify the individual involved; nonetheless, here too there are apparent behavioral influences on the subject's present life. Although the subject recalled the other five lives in fragments only, some of these also seem to have impacted her unconsciously. This study explores the nature of past-life remembering and demonstrates how presumptive past lives may exercise an influence behaviorally, emotionally, and somatically, even in the absence of conscious recall. [ABSTRACT FROM AUTHOR]

Many studies claim that visual regularities can be learned unconsciously and without explicit awareness. For example in the contextual cueing paradigm, studies often make claims using a standard reasoning based on two results: (1) a reliable response time (RT) difference between repeated vs. new stimulus displays and (2) a close-to-chance sensitivity when participants are asked to explicitly recognize repeated stimulus displays. From this pattern of results, studies routinely conclude that the sensitivity of RT responses is higher than that of explicit responses—an empirical situation we call Indirect Task Advantage (ITA). Many studies further infer from an ITA that RT effects were driven by a form of recognition that exceeds explicit memory: implicit recognition. However, this reasoning is flawed because the sensitivity underlying RT effects is never computed. To properly establish a difference, a sensitivity comparison is required. We apply this sensitivity comparison in a reanalysis of 20 contextual cueing studies showing that not a single study provides consistent evidence for ITAs. Responding to recent correlation-based arguments, we also demonstrate the absence of evidence for ITAs at the level of individual participants. This lack of ITAs has serious consequences for the field: If RT effects can be fully explained by weak but above-chance explicit recognition sensitivity, what is the empirical content of the label "implicit"? Thus, theoretical discussions in this paradigm-and likely in other paradigms using this standard reasoning-require serious reassessment because the current data from contextual cueing studies is insufficient to consider recognition as implicit. [ABSTRACT FROM AUTHOR]

We tested whether second language (L2) learners rely more on explicit memory during structural priming at lower than at higher proficiency levels (Hartsuiker & Bernolet, 2017). We compared within-L2 priming with lexical overlap in 100 low and 100 high proficiency French L2 speakers under low versus high working memory load conditions induced with a letter series recall task presented between primes and targets. The high load condition would prevent explicit recall of primes during target production. Both groups primed more under low than high load. The effect of load was similar across groups, but exploratory analyses with proficiency as a continuous variable sug)gested that, with increasing proficiency, participants primed less und discuss how these findings support the idea that learners exploit explicit memory more during priming in early versus later stages of acquisition. Overall, this study showed that explicit memory influences syntactic processing across the L2 learning trajectory. [ABSTRACT FROM AUTHOR]

Declarative memory retrieval is thought to involve reinstatement of neuronal activity patterns elicited and encoded during a prior learning episode. Furthermore, it is suggested that two mechanisms operate during reinstatement, dependent on task demands: individual memory items can be reactivated simultaneously as a clustered occurrence or, alternatively, replayed sequentially as temporally separate instances. In the current study, participants learned associations between images that were embedded in a directed graph network and retained this information over a brief 8 min consolidation period. During a subsequent cued recall session, participants retrieved the learned information while undergoing magnetoencephalographic recording. Using a trained stimulus decoder, we found evidence for clustered reactivation of learned material. Reactivation strength of individual items during clustered reactivation decreased as a function of increasing graph distance, an ordering present solely for successful retrieval but not for retrieval failure. In line with previous research, we found evidence that sequential replay was dependent on retrieval performance and was most evident in low performers. The results provide evidence for distinct performance-dependent retrieval mechanisms, with graded clustered reactivation emerging as a plausible mechanism to search within abstract cognitive maps. [ABSTRACT FROM AUTHOR]

Given continued failure of BACE1 inhibitor programs at symptomatic and prodromal stages of Alzheimer's disease (AD), clinical trials need to target the earlier preclinical stage. However, trial design is complex in this population with negative diagnosis of classical hippocampal amnesia on standard memory tests. Besides recent advances in brain imaging, electroencephalogram, and fluid-based biomarkers, new cognitive markers should be established for earlier diagnosis that can optimize recruitment to BACE1 inhibitor trials in presymptomatic AD. Notably, accelerated long-term forgetting (ALF) is emerging as a sensitive cognitive measure that can discriminate between asymptomatic individuals with high risks for developing AD and healthy controls. ALF is a form of declarative memory impairment characterized by increased forgetting rates over longer delays (days to months) despite normal storage within the standard delays of testing (20–60 min). Therefore, ALF may represent a harbinger of preclinical dementia and the impairment of systems memory consolidation, during which memory traces temporarily stored in the hippocampus become gradually integrated into cortical networks. This review provides an overview of the utility of ALF in a rational design of next-generation BACE1 inhibitor trials in preclinical AD. I explore potential mechanisms underlying ALF and relevant early-stage biomarkers useful for BACE1 inhibitor evaluation, including synaptic protein alterations, astrocytic dysregulation and neuron hyperactivity in the hippocampal-cortical network. Furthermore, given the physiological role of the isoform BACE2 as an AD-suppressor gene, I also discuss the possible association between the poor selectivity of BACE1 inhibitors and their side effects (e.g., cognitive worsening) in prior clinical trials. [ABSTRACT FROM AUTHOR]

The relationship between consciousness and individual agency is examined from a bottom-up evolutionary perspective, an approach somewhat different from other ways of dealing with the issue, but one relevant to the question of animal consciousness. Two ways are identified that would decouple the two, allowing consciousness of a limited kind to exist without agency: (1) reflex pathways that incorporate conscious sensations as an intrinsic component (InCs), and (2) reflexes that are consciously conditioned and dependent on synaptic plasticity but not memory (CCRs). Whether InCs and CCRs exist as more than hypothetical constructs is not clear, and InCs are in any case limited to theories where consciousness depends directly on EM field-based effects. Consciousness with agency, as we experience it, then belongs in a third category that allows for deliberate choice of alternative actions (DCs), where the key difference between this and CCR-level pathways is that DCs require access to explicit memory systems whereas CCRs do not. CCRs are nevertheless useful from a heuristic standpoint as a conceptual model for how conscious inputs could act to refine routine behaviors while allowing evolution to optimize phenomenal experience (i.e., qualia) in the absence of individual agency, a somewhat counterintuitive result. However, so long as CCRs are not a required precondition for the evolution of memory-dependent DC-level processes, the later could have evolved first. If so, the adaptive benefit of consciousness when it first evolved may be linked as much to the role it plays in encoding memories as to any other function. The possibility that CCRs are more than a theoretical construct, and have played a role in the evolution of consciousness, argues against theories of consciousness focussed exclusively on higher-order functions as the appropriate way to deal with consciousness as it first evolved, as it develops in the early postnatal period of life, or with the conscious experiences of animals other than ourselves. An evolutionary perspective also resolves the problem of free will, that it is best treated as a property of a species rather than the individuals belonging to that species whereas, in contrast, agency is an attribute of individuals. [ABSTRACT FROM AUTHOR]

In the present paper, we carry out a replication of a seminal paper by Kahneman, D. & Beatty, J. (1967). Perception & Psychophysics, 2(3),101–105 for using pupillometry as an implicit measure of auditory processing load, specifically, non-verbal auditory processing. While numerous papers since have supported the notion that pupillometry is a fairly reliable index of processing load in general (Zekveld, A. A., Koelewijn, T., and Kramer, S. E. (2018). Trends in Hearing, 22,1–25; Winn, M. B., Wendt, D., Koelewijn, T., and Kuchinsky, S. E. (2018). Trends in Hearing, 22,1–32), they typically have relied on memory recall, and/or more sophisticated cognitive tasks such as language comprehension or split attention. Kahneman and Beatty's paper, despite that it was published more than 50 years ago, continues to be the primary citation to support the claim that pupillometry is a reliable index of task difficulty for a simple non-verbal pitch discrimination task therefore giving us an implicit measure for listening effort (e.g.,Kramer, S. E., Lorens, A., Coninx, F., Zekveld, A. A., Piotrowska, A., & Skarzynski, H. (2013). Language and Cognitive Processes, 28(4),426–442; Schlemmer, K. B., Kulke, F., Kuchinke, L., & Van Der Meer, E. (2005). Psychophysiology, 42(4),465–472; Lisi, M., Bonato, M., and Zorzi, M. (2015). Biological Psychology, 112,39–45). This type of task takes very little explicit memory, is non-verbal, and relies heavily on more low-level, automatic perceptual processing. Using two different replication studies, one exact, and one modified, we only replicated the main result in the modified replication. The true replication failed to replicate on all nine statistical tests. Overall, our findings suggest that pupil dilation can be used as an implicit measure of task difficulty for a simple, non-semantic, auditory task, however, the robustness of the effect appears relatively weak in comparison with the original study, and the amount of variation across participants much greater. [ABSTRACT FROM AUTHOR]

A growing body of evidence demonstrates that individual differences in declarative memory may be an important predictor of second language (L2) abilities. However, the evidence comes from studies using different declarative memory tasks that vary in their reliance on verbal abilities and task demands, which preclude estimating the size of the relationship between declarative memory and L2 learning. To address these concerns, we examined the relationship between verbal and nonverbal declarative memory abilities within the same task while controlling for task demands and stimulus modality, to estimate the upper bound of the relationship between verbal and nonverbal declarative memory. Results indicate that when task demands and stimulus modality are controlled, verbal and nonverbal declarative memory abilities shared a medium-to-large amount of underlying variance. However, future studies should exercise caution in appraising associations between declarative memory abilities and L2 learning until a more precise understanding of the underlying mechanisms is achieved. [ABSTRACT FROM AUTHOR]

Research findings reveal a relationship between acute bouts of exercise and procedural/declarative memory. Prior systematic reviews report small/moderate effects of acute exercise on episodic long-term declarative memory. A somewhat overlooked issue is the influence of exercise on specific types of episodic memory processing. The primary focus of this systematic review and meta-analysis was to evaluate the effects of acute bouts of exercise prior to, during, and following encoding on free-, cued-recall, and recognition episodic memory. PubMed, Scopus, and EBSCO databases were entered, and 42 experiments were subject tometa-analysis. Exercise prior to encoding improved memory (d = 0.23) and affected free-recall (d = 0.40) tests of memory more than cued-recall (d = 0.08) or recognition (d = -0.06) memory. Exercise following encoding improved memory (d = 0.33) and affected recognition (d = 0.62) memory more than free- (d = 0.19) or cued-recall (d = 0.14) memory. Exercise during encoding did not influence memory (d = -0.04). Moderator analyses revealed that exercise before encoding impacted memory differentially on the basis of age, exercise type, and test-timing. When exercise occurred after encoding, age and exercise type, but not timing of the test influenced memory performance. Exercise before and after encoding has selective effects on episodicmemory. Additional experiments that evaluate how bouts of exercise influence memory encoding are warranted. [ABSTRACT FROM AUTHOR]

Targeted Memory Reactivation (TMR) is a noninvasive tool to manipulate memory consolidation during sleep. TMR builds on the brain's natural processes of memory reactivation during sleep and aims to facilitate or bias these processes in a certain direction. The basis of this technique is the association of learning content with sensory cues, such as odors or sounds, that are presented during subsequent sleep to promote memory reactivation. Research on TMR has drastically increased over the last decade with rapid developments. The aim of the present review is to highlight the most recent advances of this research. We focus on effects of TMR on the strengthening of memories in the declarative, procedural and emotional memory domain as well as on ways in which TMR can be used to promote forgetting. We then discuss advanced technical approaches to determine the optimal timing of TMR within the ongoing oscillatory activity of the sleeping brain as well as the specificity of TMR for certain memory contents. We further highlight the specific effects of TMR during REM sleep and in influencing dream content. Finally, we discuss recent evidence for potential applications of TMR for mental health, educational purposes and in the home setting. In conclusion, the last years of research have provided substantial advances in TMR that can guide future endeavors in research and application. [ABSTRACT FROM AUTHOR]

Steinkrauss and Slotnick (2024) reviewed neuroimaging studies linking the hippocampus with implicit memory. They conclude that there is no convincing evidence that the hippocampus is associated with implicit memory because prior studies are confounded by explicit memory (among other factors). Here, we ask a different yet equally important question: do reports of unconscious hippocampal activity reflect a Type-I error (i.e. a false positive)? We find that 39% of studies linking the hippocampus with implicit memory (7 of 18) do not report correcting for multiple comparisons. These results indicate that many unconscious hippocampal effects may reflect a Type-I error. [ABSTRACT FROM AUTHOR]

According to the traditional memory-systems view, the hippocampus is critical during explicit (conscious) long-term memory, whereas other brain regions support implicit (nonconscious) memory. In the last two decades, some fMRI studies have reported hippocampal activity during implicit memory tasks. The aim of the present discussion paper was to identify whether any implicit memory fMRI studies have provided convincing evidence that the hippocampus is associated with nonconscious processes without being confounded by conscious processes. Experimental protocol and analysis parameters included the stimulus type(s), task(s), measures of subjective awareness, explicit memory accuracy, the relevant fMRI contrast(s) or analysis, and confound(s). A systematic review was conducted to identify implicit memory studies that reported fMRI activity in the hippocampus. After applying exclusion criteria, 13 articles remained for analysis. We found that there were no implicit memory fMRI studies where subjective awareness was absent, explicit memory performance was at chance, and there were no confounds that could have driven the observed hippocampal activity. The confounds included explicit memory (including false memory), imbalanced attentional states between conditions (yielding activation of the default-mode network), imbalanced stimuli between conditions, and differential novelty. As such, not a single fMRI study provided convincing evidence that implicit memory was associated with the hippocampus. Neuropsychological evidence was also considered, and implicit memory deficits were caused by factors known to disrupt brain regions beyond the hippocampus, such that the behavioral effects could not be attributed to this region. The present results indicate that implicit memory is not associated with the hippocampus. [ABSTRACT FROM AUTHOR]

An editorial is presented on the interactions between the cortex and hippocampus during learning and memory. Topics include new insights into hippocampal contributions to memory-related behaviors, the role of cortical regions in aversive memory processing, and theoretical perspectives on cortico-hippocampal interactions.

The generalized Langevin equation (GLE) provides an attractive theoretical framework for investigating the dynamics of conformational fluctuations of polymeric systems. While the memory kernel is a central function in the GLE, explicit analytical forms for this function have been challenging to obtain, even for the simple models of polymer dynamics. Here, we achieve an explicit analytical expression for the memory kernel in the GLE for the end-to-end vector of Rouse chains in the overdamped limit. Our derivation takes advantage of the finding that the dynamics of the end-to-end vector of Rouse chains with both free ends are equivalent to those of Rouse chains with one free end and the other fixed. For the latter model, we first show that the equations of motion of the Rouse modes as well as their statistical properties can be obtained under the boundary conditions where the free end is held fixed temporarily. We then analytically solve the terms associated with intrachain interactions in the GLE. By formally comparing these terms with the GLE based on the Rouse modes, we obtain an explicit expression for the memory kernel, along with analytical forms for the potential field and the random colored noise force. Our analytical memory kernel is confirmed by numerical calculations in the Laplace space and is shown to yield asymptotic behaviors that are consistent with previous studies. Finally, we utilize our analytical result to simulate the cyclization dynamics of Rouse chains and discuss the scaling of the cyclization time with chain length. [ABSTRACT FROM AUTHOR]

In order to memorize and discriminate threatening and safe stimuli, the processing of the actual absence of threat seems crucial. Here, we measured brain activity with fMRI in response to both threat conditioned stimuli and their outcomes by combining threat learning with a subsequent memory paradigm. Participants (N = 38) repeatedly saw a variety of faces, half of which (CS+) were associated with an aversive unconditioned stimulus (US) and half of which were not (CS-). When an association was later remembered, the hippocampus had been more active (than when forgotten). However, the ventromedial prefrontal cortex predicted subsequent memory specifically during safe associations (CS- and US omission responses) and the left dorsolateral prefrontal cortex during outcomes in general (US and US omissions). In exploratory analyses of the theoretically important US omission, we found extended involvement of the medial prefrontal cortex and an enhanced functional connectivity to visual and somatosensory cortices, suggesting a possible function in sustaining sensory information for an integration with semantic memory. Activity in visual and somatosensory cortices together with the inferior frontal gyrus also predicted memory performance one week after learning. The findings imply the importance of a close interplay between prefrontal and sensory areas during the processing of safe outcomes—or 'nothing'—to establish declarative safety memory. [ABSTRACT FROM AUTHOR]

Mild cognitive impairment (MCI) is a transitional or prodromal stage of dementia in which autonomies are largely preserved (autonomies are not particularly affected). However, this condition may entail a depletion of decision-making (DM) abilities likely due to a gradual deterioration of the prefrontal cortex and subcortical brain areas underlying cognitive–emotional processing. Given the clinical implications of a decline in self-determination observed in some MCI sufferers, the present systematic review was aimed at investigating the literature addressing DM processes in patients with MCI, consistent with PRISMA guidelines. The six online databases inquired yielded 1689 research articles that were screened and then assessed based on eligibility and quality criteria. As a result, 41 studies were included and classified following the PICOS framework. Overall, patients with MCI who underwent neuropsychological assessment were found to be slightly or moderately impaired in DM abilities related to financial management, medical adherence, specific cognitive performances, risky conditions, and especially uncertain life circumstances. Comparative cross-sectional studies indicated not only mid-stage cognitive functioning in MCI but also borderline or deficit DM patterns evaluated through different tasks and procedures. Further research addressing MCI profiles suggested an association between explicit memory, executive functions, and DM performance. These findings highlight the diversity of MCI manifestations, in addition to the critical importance of DM features and correlates in patients' daily functioning. Due to a lack of consensus on both MCI and DM, this review paper sought to shed light on assessment and intervention strategies accounting for the interplay between emotion, motivation, and learning to foster DM in cognitively impaired individuals. [ABSTRACT FROM AUTHOR]

In 2023, the medical journal Resuscitation published the results of the latest study by Sam Parnia and his team, the AWARE II, in which they aimed to study consciousness after cardiac arrest and during the resuscitation process. Once again, the main objective was to detect any near-death experience (NDE) in which explicit memories occurred, either visual--of hidden images--or auditory. An important novelty was the measurement of EEG and cerebral oximetry during the brief pauses of CPR. Out of 28 interviews the researchers conducted with survivors, six patients reported NDEs, but none of them explicitly recalled either the hidden images or the auditory stimuli. However, in other patients from the study, some EEG activity that the authors deemed "compatible with consciousness" was detected during resuscitation, at least in some frequencies and brain areas. These data reopened the debate about whether the lucid consciousness of NDEs is generated by the dying brain. Parnia's own reflections in his earlier Bigelow contest essay denied this possibility. The AWARE II results did not resolve this question, but Parnia and his team suggested a possible explanation, still very theoretical, of NDEs based on brain disinhibition and ac-tivation of dormant brain circuits that would give access to "new dimensions of reality". [ABSTRACT FROM AUTHOR]

To investigate how the interplay between the declarative and procedural memory systems and learning conditions influences second language acquisition, we conducted a cross-sectional study involving 102 primary, secondary, and university English learners in a real-world English-medium educational context. Linguistic and non-linguistic measures of declarative and procedural memory were used. The untimed grammaticality judgement test was used to measure the learners' grammatical knowledge of nine features considered to have been taught explicitly (Explicitly Taught) and four others that were likely not taught explicitly (Not Explicitly Taught). To control for random variability at item and participant level, we constructed a series of linear mixed-effects models to examine the effects of memory. Overall, declarative memory was associated with both structural types across the educational levels while procedural memory was associated with learners' performance at lower levels of L2 acquisition, contrary to Ullman's declarative and procedural memory model. [ABSTRACT FROM AUTHOR]

Hippocampal ripple oscillations have been implicated in important cognitive functions such as memory consolidation and planning. Multiple computational models have been proposed to explain the emergence of ripple oscillations, relying either on excitation or inhibition as the main pacemaker. Nevertheless, the generating mechanism of ripples remains unclear. An interesting dynamical feature of experimentally measured ripples, which may advance model selection, is intra-ripple frequency accommodation (IFA): a decay of the instantaneous ripple frequency over the course of a ripple event. So far, only a feedback-based inhibition-first model, which relies on delayed inhibitory synaptic coupling, has been shown to reproduce IFA. Here we use an analytical mean-field approach and numerical simulations of a leaky integrate-and-fire spiking network to explain the mechanism of IFA. We develop a drift-based approximation for the oscillation dynamics of the population rate and the mean membrane potential of interneurons under strong excitatory drive and strong inhibitory coupling. For IFA, the speed at which the excitatory drive changes is critical. We demonstrate that IFA arises due to a speed-dependent hysteresis effect in the dynamics of the mean membrane potential, when the interneurons receive transient, sharp wave-associated excitation. We thus predict that the IFA asymmetry vanishes in the limit of slowly changing drive, but is otherwise a robust feature of the feedback-based inhibition-first ripple model. Author summary: The hippocampus plays a central role in the acquisition and consolidation of explicit memories. During sleep or rest, hippocampal neurons replay recently acquired memories, while the neuronal network exhibits high-frequency oscillations, so-called ripples. To study the potential function of ripples, their generation mechanism needs to be clarified. Here we analyze a model network of inhibitory interneurons as a potential ripple pacemaker. We derive an analytical approximation of the ripple dynamics that explains why the ripple frequency tends to decay over the course of an event (intra-ripple frequency accommodation, IFA). Studying dynamical phenomena such as IFA advances model selection and enables an understanding of how rhythmic brain activity contributes to cognitive functions. [ABSTRACT FROM AUTHOR]

Cross‐frequency coupling (CFC) between brain oscillations during non‐rapid‐eye‐movement (NREM) sleep (e.g. slow oscillations [SO] and spindles) may be a neural mechanism of overnight memory consolidation. Declines in CFC across the lifespan might accompany coinciding memory problems with ageing. However, there are few reports of CFC changes during sleep after learning in older adults, controlling for baseline effects. Our objective was to examine NREM CFC in healthy older adults, with an emphasis on spindle activity and SOs from frontal electroencephalogram (EEG), during a learning night after a declarative learning task, as compared to a baseline night without learning. Twenty‐five older adults (M [SD] age = 69.12 [5.53] years; 64% female) completed a two‐night study, with a pre‐ and post‐sleep word‐pair associates task completed on the second night. SO‐spindle coupling strength and a measure of coupling phase distance from the SO up‐state were both examined for between‐night differences and associations with memory consolidation. Coupling strength and phase distance from the up‐state peak were both stable between nights. Change in coupling strength between nights was not associated with memory consolidation, but a shift in coupling phase towards (vs. away from) the up‐state peak after learning predicted better memory consolidation. Also, an exploratory interaction model suggested that associations between coupling phase closer to the up‐state peak and memory consolidation may be moderated by higher (vs. lower) coupling strength. This study supports a role for NREM CFC in sleep‐related memory consolidation in older adults. [ABSTRACT FROM AUTHOR]

Evidence implicating theta rhythms in declarative memory encoding and retrieval, together with the notion that both retrieval and consolidation involve memory reinstatement or replay, suggests that post-learning theta rhythm modulation can promote early consolidation of newly formed memories. Building on earlier work employing theta neurofeedback, we examined whether theta-frequency transcranial alternating stimulation (tACS) can engender effective consolidation of newly formed episodic memories, compared with beta frequency stimulation or sham control conditions. We compared midline frontal and posterior parietal theta stimulation montages and examined whether benefits to memory of theta upregulation are attributable to consolidation rather than to retrieval processes by using a washout period to eliminate tACS after-effects between stimulation and memory assessment. Four groups of participants viewed object pictures followed by a free recall test during three study-test cycles. They then engaged in tACS (frontal theta montage/parietal theta montage/frontal beta montage/sham) for a period of 20 min, followed by a 2-h break. Free recall assessments were conducted after the break, 24 h later, and 7 days later. Frontal midline theta-tACS induced significant off-line retrieval gains at all assessment time points relative to all other conditions. This indicates that theta upregulation provides optimal conditions for the consolidation of episodic memory, independent of mental-state strategies. [ABSTRACT FROM AUTHOR]

This study investigated the time orientation of older adults in group conversations and its association with their memory functioning. We hypothesized that those with a greater ability to memorize recently accessed information would talk about more recent topics in natural conversations. To test this hypothesis, we used dictation data from older adults' group conversations and categorized their utterances in terms of the time to which the utterances refer. While inheriting the conventional coding categories for the temporal focus of the utterances, Past, Present, and Future, this study assigned a new category, Recent, to an utterance that referred to an event within the past month to distinguish between recent and remote memories. We further classified utterances concerning whether they were experience-based or knowledge-based, based on the distinction between two types of declarative memories: episodic and semantic memories. We found that the frequency of knowledge-based utterances had significant positive associations with memory functioning if they were Recent-tagged. However, the frequency of experience-based utterances had no significant association with memory functions, irrespective of whether the sentence was Past- or Recent-tagged. Based on the results, we discussed what type of intervention program would be effective in preserving or improving memory function in older adults. [ABSTRACT FROM AUTHOR]

In three experiments, we investigated explicit and implicit knowledge about the location of letters on the QWERTY keyboard in young students, and the mechanisms involved. Participants completed a verbal report task in which they were asked to locate the 21 letters of the Italian alphabet on a blank QWERTY keyboard (explicit memory). Subsequently, they carried out a motor production task, i.e., typing letters on a blank keyboard (implicit memory). Consistent with previous studies and several theories emphasizing the importance of implicit knowledge in typing, results showed that explicit knowledge about the QWERTY keyboard is systematically worse than procedural knowledge (Experiment 1). These two types of knowledge, however, are related. Second, we showed that explicit memory for letter position was affected when participants were engaged in a secondary task that required hands/arms movements. Specifically, loading participants' sensorimotor resources led to a decrease in explicit memory performance when the secondary task required hand/arm movements (hand/arms tapping) compared to when it required legs-feet movements (control condition). This result suggests that explicit knowledge is modulated by sensorimotor simulation (Experiment 2). Third, compared to a purely verbal response, pointing to the key on the keyboard did not improve explicit memory accuracy (Experiment 3). Taken together, the results indicate that sensorimotor simulation, and not just gestures, modulates the accessibility to explicit mental representations of verbal/spatial material, like letters on a keyboard. [ABSTRACT FROM AUTHOR]

Many commonly employed performance validity tests (PVTs) are several decades old and vulnerable to compromise, leading to a need for novel instruments. Because implicit/non-declarative memory may be robust to brain damage, tasks that rely upon such memory may serve as an effective PVT. Using a simulation design, this experiment evaluated whether novel tasks that rely upon perceptual memory hold promise as PVTs. Sixty healthy participants were provided instructions to simulate symptoms of mild traumatic brain injury (TBI), and they were compared to a group of 20 honest responding individuals. Simulator groups received varying levels of information concerning TBI symptoms, resulting in naïve, sophisticated, and test-coached groups. The Word Memory Test, Test of Memory Malingering, and California Verbal Learning Test-II Forced Choice Recognition Test were administered. To assess perceptual memory, selected images from the Gollin Incomplete Figures and Mooney Closure Test were presented as visual perception tasks. After brief delays, memory for the images was assessed. No group differences emerged on the perception trials of the Gollin and Mooney figures, but simulators remembered fewer images than the honest responders. Simulator groups differed on the standard PVTs, but they performed equivalently on the Gollin and Mooney figures, implying robustness to coaching. Relying upon a criterion of 90% specificity, the Gollin and Mooney figures achieved at least 90% sensitivity, comparing favorably to the standard PVTs. The Gollin and Mooney figures hold promise as novel PVTs. As perceptual memory tests, they may be relatively robust to brain damage, but future research involving clinical samples is necessary to substantiate this assertion. [ABSTRACT FROM AUTHOR]

During the learning process, music can activate important neural areas in the brain, promoting the retention of information and memory formation. However, studies testing music effects on memory had found different improvements, which could be due to the methodological differences across studies. Thus, the purpose of this article was to systematically review the literature and meta-analyze the effects of music on Rattus norvegicus' explicit memory (Maze tests) only in controlled investigations. The seven studies included led to a very homogeneous analysis (I2 = 0%), confirming the consistency of the significant standardized mean difference (SMD) between the memory of animals exposed and not exposed to music (SMD 0.60 (95% CI 0.38; 0.83, p < 0.001)). Exploratory analysis suggests music benefits on memory can be acquired when begun at any age, when tested with the three types of mazes evaluated, with exposure lasting from 8 to 83 days and when the age on test day was either under 30 days or over 30 days. To expand the actual understanding of music effects on memory, future studies should investigate different types of music and animal species, with different sex and health conditions, at different time points. [ABSTRACT FROM AUTHOR]

The author cites the prominence of theories that locate serious adult psychopathology in the preverbal infant's inability to formulate or represent traumatic experience. The work of two such authors, H. Levine and D. B. Stern, is briefly considered. The frame of reference for this investigation is that clinical and academic research findings are highly relevant to psychoanalytic theorizing. It is argued that when such findings are considered, a view of the infant with "primordial and unrepresented" states of mind has little evidence to support it. In fact, research findings summarized herein point to an opposite view: that of the "competent infant," one with highly accurate perceptual discrimination capacities and an innate ability to register and represent subjective experience in both procedural and declarative memory, even prenatally. Given the infant's competencies, it seems implausible to hold that representational deficits are at the heart of serious adult psychopathology, which is instead seen to be the result of defensive maneuvers against unknowable and unspeakable truth rather than the absence of a preverbal representational capacity. Current research findings seem to pose a significant challenge for psychoanalytic theories that espouse "primitive mental states"; "unrepresented," "unformulated," or "unsymbolized" experience; or "nonconscious" states. [ABSTRACT FROM AUTHOR]

Background: Uncovering the functional relevance underlying verbal declarative memory (VDM) genome-wide association study (GWAS) results may facilitate the development of interventions to reduce age-related memory decline and dementia. Methods: We performed multi-omics and pathway enrichment analyses of paragraph (PAR-dr) and word list (WL-dr) delayed recall GWAS from 29,076 older non-demented individuals of European descent. We assessed the relationship between single-variant associations and expression quantitative trait loci (eQTLs) in 44 tissues and methylation quantitative trait loci (meQTLs) in the hippocampus. We determined the relationship between gene associations and transcript levels in 53 tissues, annotation as immune genes, and regulation by transcription factors (TFs) and microRNAs. To identify significant pathways, gene set enrichment was tested in each cohort and meta-analyzed across cohorts. Analyses of differential expression in brain tissues were conducted for pathway component genes. Results: The single-variant associations of VDM showed significant linkage disequilibrium (LD) with eQTLs across all tissues and meQTLs within the hippocampus. Stronger WL-dr gene associations correlated with reduced expression in four brain tissues, including the hippocampus. More robust PAR-dr and/or WL-dr gene associations were intricately linked with immunity and were influenced by 31 TFs and 2 microRNAs. Six pathways, including type I diabetes, exhibited significant associations with both PAR-dr and WL-dr. These pathways included fifteen MHC genes intricately linked to VDM performance, showing diverse expression patterns based on cognitive status in brain tissues. Conclusions: VDM genetic associations influence expression regulation via eQTLs and meQTLs. The involvement of TFs, microRNAs, MHC genes, and immune-related pathways contributes to VDM performance in older individuals. [ABSTRACT FROM AUTHOR]

Hunger refers to (1) the meaning of certain bodily sensations; (2) a mental state of anticipation that food will be good to eat; and (3) an organizing principal, which prioritizes feeding. Definitions (1) and (2) are the focus here, as (3) can be considered their consequent. Definition (1) has been linked to energy-depletion models of hunger, but these are no longer thought viable. Definition (2) has been linked to learning and memory (L&M) models of hunger, but these apply just to palatable foods. Nonetheless, L&M probably forms the basis for hunger generally, as damage to declarative memory can eradicate the experience of hunger. Currently, there is no general L&M model of hunger, little understanding of how physiology intersects with a L&M approach, and no understanding of how Definitions (1) and (2) are related. We present a new L&M model of human hunger. People learn associations between internal (e.g., tummy rumbles) and external cues (e.g., brand names) and food. These associations can be to specific foods (episodic memories) or food-related categories (semantic memories). When a cue is encountered, it may lead to food-related memory retrieval. If retrieval occurs, the memory's affective content allows one to know if food will be good to eat now—hunger—a cognitive operation learned in childhood. These memory processes are acutely inhibited during satiety, and chronically by multiple biological parameters, allowing physiology to modulate hunger. Implications are considered for the process of making hunger judgments, thirst, the cephalic phase response, and motivational and lay theories of hunger. [ABSTRACT FROM AUTHOR]

Recent experimental evidence has led to the idea that the neural mechanisms supporting spatial navigation have been flexibly adapted to organize concepts and memories through spatial codes. The "phylogenetic continuity hypothesis" (Buszáki & Moser, 2013) further proposes that the mechanisms supporting episodic and semantic memory would have respectively evolved from self-based (i.e. egocentric) and map-based (i.e. allocentric) spatial navigation mechanisms. Recent studies have observed traces of this phylogenetic continuity in human behavior, but the full original model has not yet been tested. Here, we evaluated the relationships between the four model components by using two sets of tasks in the spatial navigation and declarative memory domains based on complex materials and emphasizing the self vs. map-based processing (i.e. route vs. survey component for spatial navigation and episodic vs. semantic component for declarative memory). Consistent with the model predictions, the results of a multiple multivariate regression analysis revealed a specific across-domain relationship, such that route-based navigation performance specifically predicted episodic memory performance (self-based, egocentric components), while survey navigation performance specifically predicted the semantic memory one (map-based, allocentric components). The results of an additional regression analysis on the within-domain transformation process from self-based to map-based representations confirmed that route-based navigation specifically predicted survey navigation, while episodic memory specifically predicted semantic memory. Our results provide further behavioral evidence in support of the general hypothesis that the neural machinery evolved to map the physical world might have been recycled to organize memory and conceptual knowledge. Crucially, they also support the more specific hypothesis that the organizational principles involved in higher-level processing of information have inherited the fundamental distinction between different reference frames (egocentric vs. allocentric) for navigation in the physical world. [ABSTRACT FROM AUTHOR]

Cognition refers to the mental action or process through which an individual acquires knowledge solves problems and makes decisions for the future. In other words, cognition may be defined as the mental processes which account for the daily activities carried out by an individual. Deficits in these mental processes tend to affect the memory, attention, verbal a n d non-verbal learning, visual and auditory processing, and motor functioning of an individual, thereby resulting in cognitive impairment. Memory is classified into two types, that is, explicit memory and implicit memory. Explicit memory involves the conscious recall of the information received in the past while implicit memory refers to the information or knowledge which is unconsciously and effortlessly recalled. [ABSTRACT FROM AUTHOR]

In the modern system of criticism and analysis of works, the meaning of the text depends on the discovery of the relationships between the subject and the pre-texts, the implicit and explicit memories of the work, as well as the metatextual components that give birth to it; intertextual analysis forms its theoretical basis and methodology. Among the theorists of this method, Roland Barthes allows the audience to get new and creative interpretations and meanings by the arrangement of the texts and the discovery of the overt and covert layers of the works in each other. On the other hand, between history and literature, in addition to commonalities and philosophical confrontations, there are hidden links and emerging meanings; one of the examples of which can be found in the systematic connection between Juvayni's historiography in Jahangushay and Ferdowsi's epic writing in Shahnameh. Therefore, adopting a descriptive-analytical approach, this research tries to discover a new meaning in why Jahangushay history was created in relation to its dominant pre-text, Shahnameh. Considering the relationships between aspects and dimensions of the influence in the formation of some structural elements, the comparative explanation of the literary perspective, and the analysis of the identity and motivational categories of the texts in relation to each other, one can conclude that in his historiography, not only was Juvayni influenced by Ferdowsi's technique and method, but in a confrontational system, he has tried to recreate a text on the level of the Shahnameh and revive a national epic in prose form. [ABSTRACT FROM AUTHOR]

Stress impacts prefrontal cortex (PFC) activity and modulates working memory performance. In a recent study, stimulating the dorsolateral PFC (dlPFC) using transcranial direct current stimulation (tDCS) interacted with social stress in modulating participants' working memory. More specifically, stress disrupted the enhancing effects of dlPFC tDCS on working memory performance. The current study aimed to further explore these initial findings by randomizing healthy females to four experimental conditions (N = 130); stimulation (right dlPFC tDCS vs. sham) and stress manipulation (social stress vs. control). Participants performed cognitive tasks (i.e., visual working memory task and a visual declarative memory task) at baseline and post-stimulation. They also completed self-report measures of stress and anxiety. A significant stimulation × stress interaction was evident in the declarative memory (One-Card Learning, OCL) task, while working memory performance was unaffected. Though tDCS stimulation and stress did not interact to affect working memory, further research is warranted as these initial findings suggest that immediate visual-memory learning may be affected by these factors. The limited number of earlier studies, as well as the variability in their designs, provides additional impetus for studying the interactive effects of stress and tDCS on human visual learning. [ABSTRACT FROM AUTHOR]

Two assumptions commonly applied in convection schemes—the diagnostic and quasi‐equilibrium assumptions—imply that convective activity (e.g., convective precipitation) is controlled only by the large‐scale (macrostate) environment at the time. In contrast, numerical experiments indicate a "memory" or dependence of convection also on its own previous activity whereby subgrid‐scale (microstate) structures boost but are also boosted by convection. In this study we investigated this memory by comparing single‐column model behavior in two idealized tests previously executed by a cloud‐resolving model (CRM). Conventional convection schemes that employ the diagnostic assumption fail to reproduce the CRM behavior. The memory‐capable org and Laboratoire de Météorologie Dynamique Zoom cold pool schemes partially capture the behavior, but fail to fully exhibit the strong reinforcing feedbacks implied by the CRM. Analysis of this failure suggests that it is because the CRM supports a linear (or superlinear) dependence of the subgrid structure growth rate on the precipitation rate, while the org scheme assumes a sublinear dependence. Among varying versions of the org scheme, the growth rate of the org variable representing subgrid structure is strongly associated with memory strength. These results demonstrate the importance of parameterizing convective memory, and the ability of idealized tests to reveal shortcomings of convection schemes and constrain model structural assumptions. Plain Language Summary: Convection (clouds) has memory, can remember its own history, and is affected by it when evolving to the next step. However, this memory effect is often neglected in convection schemes, which are approximate sub‐models used to represent (parameterize) convective processes in climate models whose resolutions are too low to properly resolve convection. In this study we apply two simple tests to probe the memory behavior of various convection schemes. We found that most conventional schemes fail to mimic the memory response of a cloud‐resolving model (CRM) where convection is properly represented. In two schemes where memory is parameterized, their responses are more similar but still bear significant differences to the CRM. We show that this discrepancy can be explained by the equations used in these schemes. For one of the schemes, we also found that the strength of memory is related to the growth rate of the memory variable, rather than its absolute value. Overall, our results demonstrate the importance of taking memory into account in convection schemes, and show that the two tests implemented here are simple but useful in shining light on potential shortcomings of convection schemes and hence also ways to improve them. Key Points: Several convection schemes were tested via two recently proposed, idealized experiments designed to isolate memory‐like behaviorAll schemes either fail to show any such behavior, or show weaker memory than an explicit cloud‐resolving modelBy fitting simple equation sets to the results, structural assumptions and parameters related to subgrid memory processes can be constrained [ABSTRACT FROM AUTHOR]

Knowing a language involves knowing a large number of idiosyncratic units such as individual words and collocations which must be learned from the input. This study explores the role of implicit and explicit memory, as well as language experience, and specifically print exposure, with regard to adult native English speakers' knowledge of vocabulary and collocations. Consistent with prior research, our findings reveal a strong correlation between print exposure and performance on both language tasks. However, contrary to predictions, there were no significant effects of either implicit or explicit memory on either task. We argue that this is most likely due to the fact that language learning relies primarily on memory for associations between form and meaning and between words rather than memory sequences of meaningless phonological forms. [ABSTRACT FROM AUTHOR]

One of the most common distinctions in long-term memory is that between semantic (i.e., general world knowledge) and episodic (i.e., recollection of contextually specific events from one's past). However, emerging cognitive neuroscience data suggest a surprisingly large overlap between the neural correlates of semantic and episodic memory. Moreover, personal semantic memories (i.e., knowledge about the self and one's life) have been studied little and do not easily fit into the standard semantic-episodic dichotomy. Here, we used fMRI to record brain activity while 48 participants verified statements concerning general facts, autobiographical facts, repeated events, and unique events. In multivariate analysis, all four types of memory involved activity within a common network bilaterally (e.g., frontal pole, paracingulate gyrus, medial frontal cortex, middle/superior temporal gyrus, precuneus, posterior cingulate, angular gyrus) and some areas of the medial temporal lobe. Yet the four memory types differentially engaged this network, increasing in activity from general to autobiographical facts, from autobiographical facts to repeated events, and from repeated to unique events. Our data are compatible with a component process model, in which declarative memory types rely on different weightings of the same elementary processes, such as perceptual imagery, spatial features, and self-reflection. [ABSTRACT FROM AUTHOR]

Objective: To develop a classification framework based on random forest (RF) modeling to outline the declarative memory profile of patients with panic disorder (PD) compared to a healthy control sample. Methods: We developed RF models to classify the declarative memory profile of PD patients in comparison to a healthy control sample using the Rey Auditory Verbal Learning Test (RAVLT). For this study, a total of 299 patients with PD living in the city of Rio de Janeiro (70.9% females, age 39.9 6 7.3 years old) were recruited through clinician referrals or self/family referrals. Results: Our RF models successfully predicted declarative memory profiles in patients with PD based on RAVLT scores (lowest area under the curve [AUC] of 0.979, for classification; highest root mean squared percentage [RMSPE] of 17.2%, for regression) using relatively bias-free clinical data, such as sex, age, and body mass index (BMI). Conclusions: Our findings also suggested that BMI, used as a proxy for diet and exercises habits, plays an important role in declarative memory. Our framework can be extended and used as a prospective tool to classify and examine associations between clinical features and declarative memory in PD patients. [ABSTRACT FROM AUTHOR]

The recall of a distant memory may appear satisfying and suggest successful retrieval is inherently rewarding. If the brain incentivizes retrieval attempts on the prospect of an internal retrieval reward, then the desire for that reward might natively reinforce declarative memory access. But what determines the level of retrieval satisfaction? We tested the idea that retrieval attempt uncertainty drives retrieval satisfaction. For instance, the more distant the memory, the more satisfying should it be to successfully retrieve it. Alternatively, the brain issues rewards based on the level of confidence in recall independent of the recall achievement. If so, then more confident retrieval is also more satisfying. In an online experiment containing five Swahili-English word pair study sessions spaced across one week, we tested 30 English-speaking participants' recall satisfaction and memory confidence during learning as well as in a final cued recall test. We hypothesized that retrieval satisfaction should either increase or decrease with retrieval uncertainty as indicated by time since encoding, and how little in overall they recalled from the session. We found that retrieval satisfaction decreased with time since encoding and with study session retrieval performance. Moreover, we found that retrieval confidence and satisfaction ratings were highly related in the experiment. We also found a reliable interaction between confidence and word difficulty indicating that confidently recalled difficult items induced more satisfaction. Thus, the brain appears to reward both retrieval confidence and to a lesser extent, fruitful retrieval effort. Our findings may explain seemingly irrational self-regulated study behavior such as avoiding learning-efficient but difficult training protocols, as effects of a system rationally seeking to accrue intrinsic cognitive reward. [ABSTRACT FROM AUTHOR]

The chronic intake of 3,4‐methylenedioxymethamphetamine (MDMA, "ecstasy") bears a strong risk for sustained declarative memory impairments. Although such memory deficits have been repeatedly reported, their neurofunctional origin remains elusive. Therefore, we here investigate the neuronal basis of altered declarative memory in recurrent MDMA users at the level of brain connectivity. We examined a group of 44 chronic MDMA users and 41 demographically matched controls. Declarative memory performance was assessed by the Rey Auditory Verbal Learning Test and a visual associative learning test. To uncover alterations in the whole brain connectome between groups, we employed a data‐driven multi‐voxel pattern analysis (MVPA) approach on participants' resting‐state functional magnetic resonance imaging data. Recent MDMA use was confirmed by hair analyses. MDMA users showed lower performance in delayed recall across tasks compared to well‐matched controls with moderate‐to‐strong effect sizes. MVPA revealed a large cluster located in the left postcentral gyrus of global connectivity differences between groups. Post hoc seed‐based connectivity analyses with this cluster unraveled hypoconnectivity to temporal areas belonging to the auditory network and hyperconnectivity to dorsal parietal regions belonging to the dorsal attention network in MDMA users. Seed‐based connectivity strength was associated with verbal memory performance in the whole sample as well as with MDMA intake patterns in the user group. Our findings suggest that functional underpinnings of MDMA‐related memory impairments encompass altered patterns of multimodal sensory integration within auditory processing regions to a functional heteromodal connector hub, the left postcentral gyrus. In addition, hyperconnectivity in regions of a cognitive control network might indicate compensation for degraded sensory processing. [ABSTRACT FROM AUTHOR]

Posttraumatic stress disorder (PTSD) is associated with changes in multiple neurophysiological systems, including verbal declarative memory deficits. Vagus Nerve Stimulation (VNS) has been shown in preliminary studies to enhance function when paired with cognitive and motor tasks. The purpose of this study was to analyze the effect of transcutaneous cervical VNS (tcVNS) on attention, declarative and working memory in PTSD patients. Fifteen PTSD patients were randomly assigned to active tcVNS (N = 8) or sham (N = 7) stimulation in a double-blinded fashion. Memory assessment tests including paragraph recall and N-back tests were performed to assess declarative and working memory function when paired with active/sham tcVNS once per month in a longitudinal study during which patients self-administered tcVNS/sham twice daily. Active tcVNS stimulation resulted in a significant improvement in paragraph recall performance following pairing with paragraph encoding for PTSD patients at two months (p < 0.05). It resulted in a 91 % increase in paragraph recall performance within group (p = 0.03), while sham tcVNS exhibited no such trend in performance improvement. In the N-back study, positive deviations in accuracy, precision and recall measures on different day visits (7,34,64,94) of patients with respect to day 1 revealed a pattern of better performance of the active tcVNS population compared to sham VNS which did not reach statistical significance. Our sample size was small. These preliminary results suggest that tcVNS improves attention, declarative and working memory, which may improve quality of life and productivity for patients with PTSD. Future studies are required to confirm these results. • We analyzed the effect of transcutaneous cervical VNS (tcVNS) on attention, declarative and working memory in PTSD patients. • We did a longitudinal study with memory assessment tests to assess memory function when paired with active/sham stimulation. • Results suggested an improvement in declarative and working memory performance in the active tcVNS population. [ABSTRACT FROM AUTHOR]

The prevailing view in human cognitive neuroscience associates the medial temporal lobes (MTLs) with declarative memory. Compelling experimental evidence has, however, demonstrated that these regions are specialized according to the representations processed, irrespective of the cognitive domain assessed. This account was supported by the study of patients with bilateral medial temporal amnesia, who exhibit impairments in perceptual tasks involving complex visual stimuli. Yet, little is known regarding the impact of unilateral MTL damage on complex visual abilities. To address this issue, we administered a visual matching task to 20 patients who underwent left (N = 12) or right (N = 8) anterior temporal lobectomy for drug‐resistant epilepsy and to 38 healthy controls. Presentation viewpoint was manipulated to increase feature ambiguity, as this is critical to reveal impairments in perceptual tasks. Similar to control participants, patients with left‐sided damage succeeded in all task conditions. In contrast, patients with right‐sided damage had decreased accuracy compared with that of the other two groups, as well as increased response time. Notably, the accuracy of those with right‐sided damage did not exceed chance level when feature ambiguity was high (i.e., when stimuli were presented from different viewpoints) for the most complex classes of stimuli (i.e., scenes and buildings, compared with single objects). The pattern reported in bilateral patients in previous studies was therefore reproduced in patients with right, but not left, resection. These results suggest that the complex visual‐representation functions supported by the MTL are right‐lateralized, and raise the question as to how the representational account of these regions applies to representations supported by left MTL regions. [ABSTRACT FROM AUTHOR]

According to the commonly accepted opinion, memory engrams are formed and stored at the level of neural networks due to a change in the strength of synaptic connections between neurons. This hypothesis of synaptic plasticity (HSP), formulated by Donald Hebb in the 1940s, continues to dominate the directions of experimental studies and the interpretations of experimental results in the field. The universal acceptance of the HSP has transformed it from a hypothesis into an incontrovertible theory. In this article, I show that the entire body of experimental and clinical data obtained in studies of long-term memory in mammals and humans is inconsistent with the HSP. Instead, these data suggest that long-term memory is formed and stored at the intracellular level where it is reliably protected from ongoing synaptic activity, including pathological epileptic activity. It seems that the generally accepted HSP became a serious obstacle to understanding the mechanisms of memory and that progress in this field requires rethinking this doctrine and shifting experimental efforts toward exploring the intracellular mechanisms. [ABSTRACT FROM AUTHOR]