Episodic Memory Processes Research Articles

An embedded computational framework of memory: Accounting for the influence of semantic information in verbal short-term memory

We introduce the Embedded Computational Framework of Memory (eCFM), a model that integrates structured semantic word representations with an instance-based memory model to account for the influence of semantic information in verbal short-term memory. The eCFM combines principles from the episodic MINERVA 2 model and the semantic Latent Semantic Analysis model. After reviewing how semantic information impacts verbal short-term memory performance, we demonstrate eCFM’s ability to reconcile various phenomena within a common computational framework. Our model captures key findings, such as the influence of semantic information in serial recall, its reduction in serial reconstruction, and the impact of task difficulty on semantic information. In five experiments, we tested predictions derived from the eCFM. Experiments 1 and 2 manipulated list organization, with Experiment 1 using alternating lists of related or unrelated words and Experiment 2 using blocked lists. Experiment 3 varied presentation rates, Experiment 4 revisited the detrimental effect of semantic information on order information, and Experiment 5 explored false recall. We found that semantic information interacts with list composition, presentation rate affects the magnitude of its influence, and semantic information impacts order information contrary to the dominant view. Additionally, increasing the number of related study words to a non-studied semantic lure boosts false recall. The eCFM captured these findings as well as memory at the item level. Our demonstration provides insight into the cognitive mechanisms underlying verbal short-term memory and the interplay of semantic and episodic memory processes in recall.

The Impact of Episodic Memory on Decision-Making in Aging: Scenarios from Everyday Life Situations.

Background: Decision-making is a highly complex process that depends on numerous cognitive functions, such as episodic memory. It is also influenced by aging. However, how changes in episodic memory with age contribute to changes in decision-making is not clear yet. Objective: This work aimed to examine the role of two memory processes, recollection and familiarity, in decision-making in ageing. Method: Thirty young adults and 30 older adults performed two episodic memory tasks: recognition, which allowed for the measurement of recollection and familiarity, and recall, which allowed for the measurement of recollection. In both tasks, they first viewed a series of pictures and then were asked to recognise or recall them respectively. They also performed an original scenario task based on situations inspired by everyday life, evaluating decision-making under conditions of either risk or ambiguity. In this task, participants were presented with short descriptions of situations requiring a decision and had to choose between two given options. Results: Lower performances was observed in recall and recognition tasks in older than in young adults. In the scenarios task, young adults sought significantly more risk and ambiguity than older adults. In both young and older adults, recollection and familiarity processes were involved differently in decision-making. The former is more involved in decision-making under ambiguity, and the latter in decision-making under risk. Conclusions: The results suggest that decision-making changes with age, but that the involvement of the episodic memory, familiarity and recollection processes, does not appear to vary with age.

Systemic cytokines related to memory function 6–9 months and 12–15 months after SARS-CoV-2 infection

Cognitive symptoms persisting beyond the acute phase of COVID-19 infection are commonly described for up to 2 years after infection. The relationship between cognitive performance, in particular episodic memory processes observed chronically after infection, and cytokine levels in the acute phase of COVID-19 has not yet been identified in humans. To determine whether the levels of cytokines IL1β, IL-6 and TNFα secreted in the acute phase of SARS-CoV-2 infection are associated and predict verbal and visuospatial episodic memory performance in humans 6 to 9 months and 12 to 15 months post-infection. The associations and predictive value of the concentration of cytokines measured in acute phase (IL-1β, IL-6, TNFα) from plasma samples of N = 33 hospitalized COVID-19 patients (mean age 61 years, 39–78, 65% in intensive care) in relation to their verbal and visuospatial episodic memory performance measured at 6–9 months and 12–15 months post-infection were analyzed. To do this, we used Spearman correlations and generalised linear mixed models. IL-1β levels were associated with verbal episodic memory total recall scores 6–9 months post-infection. At 12–15 months post-infection IL-6 predicted verbal episodic memory score. This study demonstrated that the severity of inflammatory reaction at acute phase of SARS-CoV-2 infection predicts verbal episodic memory performance in the long-term post-infection.

Association of chronotype with language and episodic memory processing in children: implications for brain structure.

Chronotype refers to individual preference in circadian cycles and is associated with psychiatric problems. It is mainly classified into early (those who prefer to be active in the morning and sleep and wake up early) and late (those who prefer to be active in the evening and sleep and wake up late) chronotypes. Although previous research has demonstrated associations between chronotype and cognitive function and brain structure in adults, little is known regarding these associations in children. Here, we aimed to investigate the relationship between chronotype and cognitive function in children. Moreover, based on the significant association between chronotype and specific cognitive functions, we extracted regions-of-interest (ROI) and examined the association between chronotype and ROI volumes. Data from 4,493 children (mean age of 143.06 months) from the Adolescent Brain Cognitive Development Study were obtained, wherein chronotype (mid-sleep time on free days corrected for sleep debt on school days) was assessed by the Munich Chronotype Questionnaire. Subsequently, the associations between chronotype, cognitive function, and ROI volumes were evaluated using linear mixed-effects models. Behaviorally, chronotype was negatively associated with vocabulary knowledge, reading skills, and episodic memory performance. Based on these associations, the ROI analysis focused on language-related and episodic memory-related areas revealed a negative association between chronotype and left precentral gyrus and right posterior cingulate cortex volumes. Furthermore, the precentral gyrus volume was positively associated with vocabulary knowledge and reading skills, while the posterior cingulate cortex volume was positively associated with episodic memory performance. These results suggest that children with late chronotype have lower language comprehension and episodic memory and smaller brain volumes in the left precentral gyrus and right posterior cingulate cortex associated with these cognitive functions.

Neurocognitive mechanisms of emotional interference in native and foreign languages: evidence from proficient bilinguals.

Currently available data show mixed results as to whether the processing of emotional information has the same characteristics in the native (L1) as in the second language (L2) of bilinguals. We conducted a functional magnetic resonance imaging (fMRI) experiment to shed light on the neurocognitive mechanisms underlying bilinguals' emotional processing in L1 and L2 during an emotional interference task (i.e., the Emotional Stroop Task - EST). Our sample comprised proficient Italian-English bilinguals who learned their L2 during childhood mainly in instructional rather than immersive contexts. In spite of no detectable behavioural effects, we found stronger brain activations for L1 versus L2 emotional words in sectors of the posteromedial cortex involved in attention modulation, episodic memory, and affective processing. While fMRI findings are consistent with the hypothesis of a stronger emotional resonance when processing words in a native language, our overall pattern of results points to the different sensitivity of behavioural and hemodynamic responses to emotional information in the two languages of bilingual speakers.

Social episodic memory in severe alcohol use disorder: Positive encoding bias and negative bias in accessibility of interpersonal information.

Alterations in higher-order social cognition are well documented in individuals with severe alcohol use disorder (SAUD). However, the basic mechanisms underpinning them are not well understood. This knowledge gap hampers the development of targeted therapeutic interventions. Here, we investigated whether individuals with SAUD show abnormalities in social episodic memory processes, which may represent relevant candidate mechanisms for alterations in social cognition. Recently detoxified patients with SAUD and matched healthy controls (HCs) completed two experimental tasks. We first used a Social Recognition Task in 40 SAUD patients and 40 HCs to measure the participants' ability to implicitly memorize the facial identity and emotion of novel interpersonal cues (i.e., dynamic facial expressions of anger and happiness). We then used a Social Memory Accessibility Task in 29 SAUD patients and 30 HCs) to measure participants' access to and fluency for already existing social memories by asking them to retrieve as many specific positive and negative interpersonal events as possible within equal time limits. In the Social Recognition Task, we found that, compared to HCs, patients with SAUD had a globally lower recognition performance for the facial identities of novel social stimuli, but a preserved bias toward positive information. Conversely, in the social memory accessibility task, patients showed greater access to and fluency for negative interpersonal memories than controls (no group differences were observed for positive ones), resulting in a negative accessibility bias. This exploration of episodic social memory in individuals with SAUD showed (1) a preserved bias for the encoding of positive versus negative novel social information, and (2) greater access to negative than positive interpersonal memories. These results enhance our understanding of socio-affective processing in individuals with SAUD and identify social memory alterations that may contribute to social cognition and interpersonal difficulties.

The role of theta and gamma oscillations in item memory, source memory, and memory confidence.

Theta and gamma oscillations have been linked to episodic memory processes in various studies. Both oscillations seem to be vital for processes guided by the medial temporal lobe, such as the retrieval of information from memory. While theta oscillations increase with successful memory, it is unclear what the unique contribution of theta is to various subcomponents of memory. On the other hand, memory-related gamma oscillations have been mainly reported in the hippocampus, leaving the role of neocortical gamma in memory underexplored. In this study, we investigated how unique variability in memory accuracy and memory confidence contributes to fluctuations in theta and gamma power. To this end, we recorded EEG from 54 participants while they performed a source memory task. From this task we obtained their item memory accuracy, source memory accuracy, item memory confidence, and source memory confidence. These behavioral measures were put in a trial-by-trial linear mixed effects model to uncover their unique contribution to the oscillatory power in frontal and parietal regions. Our results are in line with the involvement of theta oscillations in both memory accuracy and confidence, but seem to indicate a main role for theta oscillations in memory-related confidence. In addition, we found that gamma oscillations play various roles in memory processing, dependent on brain region.

The effects of acute exercise on long-term episodic memory: a systematic review and meta-analysis

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 to meta-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 episodic memory. Additional experiments that evaluate how bouts of exercise influence memory encoding are warranted.Systematic review registrationPROSPERO, identifier CRD42020202784.

Remembering what we imagine: the role of event schemas in shaping how imagined autobiographical events are recalled.

Much like recalling autobiographical memories, constructing imagined autobiographical events depends on episodic memory processes. The ability to imagine events contributes to several future-oriented behaviors (e.g., decision-making, problem solving), which relies, in part, on the ability to remember the imagined events. A factor affecting the memorability of such events is their adherence to event schemas-conceptualizations of how events generally unfold. In the current study, we examined how two aspects of event schemas-event expectancy and familiarity-affect the ability to recall imagined events. Participants first imagined and described in detail autobiographical events that either aligned with or deviated from an event, expected to occur in a context (e.g., a kitchen) that was either familiar or unfamiliar. This resulted in imaginations ranging from maximally schema-congruent (expected events in a familiar context) to maximally novel (unexpected events in an unfamiliar context). Twenty-four hours later, participants recalled these imagined events. Recollections were scored for the number of reinstated details from the imaginations and the number of newly added details. We found greater reinstatement of details for both the maximally congruent and maximally novel events, while maximally novel events were recalled more precisely than other events (i.e., fewer added details). Our results indicate a complementary benefit to remembering schematic and novel imagined events, which may guide equally important but distinct future-oriented behaviors.

Iron Deposition and Distribution Across the Hippocampus Is Associated with Pattern Separation and Pattern Completion in Older Adults at Risk for Alzheimer's Disease.

Elevated iron deposition in the brain has been observed in older adult humans and persons with Alzheimer's disease (AD), and has been associated with lower cognitive performance. We investigated the impact of iron deposition, and its topographical distribution across hippocampal subfields and segments (anterior, posterior) measured along its longitudinal axis, on episodic memory in a sample of cognitively unimpaired older adults at elevated familial risk for AD (N = 172, 120 females, 52 males; mean age = 68.8 ± 5.4 years). MRI-based quantitative susceptibility maps were acquired to derive estimates of hippocampal iron deposition. The Mnemonic Similarity Task was used to measure pattern separation and pattern completion, two hippocampally mediated episodic memory processes. Greater hippocampal iron load was associated with lower pattern separation and higher pattern completion scores, both indicators of poorer episodic memory. Examination of iron levels within hippocampal subfields across its long axis revealed topographic specificity. Among the subfields and segments investigated here, iron deposition in the posterior hippocampal CA1 was the most robustly and negatively associated with the fidelity memory representations. This association remained after controlling for hippocampal volume and was observed in the context of normal performance on standard neuropsychological memory measures. These findings reveal that the impact of iron load on episodic memory performance is not uniform across the hippocampus. Both iron deposition levels as well as its spatial distribution, must be taken into account when examining the relationship between hippocampal iron and episodic memory in older adults at elevated risk for AD.

A Cognitive Robotics Implementation of Global Workspace Theory for Episodic Memory Interaction With Consciousness

Artificial general intelligence revived in recent years after people achieved significant advances in machine learning and deep learning. This leads to the thinking of how real intelligence could be created. Consciousness theories believe that general intelligence is essentially conscious, yet no universal definition is agreed upon. In this work, Global Workspace Theory is implemented and integrated with crucial cognitive components. With the focus on episodic memory and inspiration from the nature of episodic memory in psychology and neuroscience, the episodic memory component is implemented within the Global Workspace framework. In our experiment, the robotic agent operates in a real-world interactive context, forming episodic memory and demonstrating static, temporal, and context memory capabilities during interactions. Consciousness in this work engages in all formation, maintenance, and retrieval processes of episodic memory. The novelty and contributions of this work are 1) this work is implementing episodic memory within the consciousness framework, suggesting the sustainable potential of such an integrated approach to cognitive agents with AGI; 2) Regarding the limited examples in consciousness-based cognitive architectures, this work attempts to contribute to the diversity of perspectives and approaches; 3) Extant episodic memory implementations are suffering from various limitations, while this work summarises some key features for modelling episodic memory within a cognitive architecture; 4) Authors discuss the relationship between episodic memory, consciousness, and general intelligence, proposing the compatibility and relationship between machine consciousness and other AGI research. It is believed that a better alignment between them would further boost the fusion of diverse research for achieving desired cognitive machines.

Unilateral hippocampal sparing during whole brain radiotherapy for multiple brain metastases: narrative and critical review.

The landscape of brain metastases radiotherapy is evolving, with a shift away from whole-brain radiotherapy (WBRT) toward targeted stereotactic approaches aimed at preserving neurocognitive functions and maintaining overall quality of life. For patients with multiple metastases, especially in cases where targeted radiotherapy is no longer feasible due to widespread dissemination, the concept of hippocampal sparing radiotherapy (HA_WBRT) gains prominence. In this narrative review we explore the role of the hippocampi in memory formation and the implications of their postradiotherapy lateral damage. We also consider the potential advantages of selectively sparing one hippocampus during whole-brain radiotherapy (WBRT). Additionally, by systematic evaluation of relevant papers published on PubMed database over last 20 years, we provide a comprehensive overview of the various changes that can occur in the left or right hippocampus as a consequence of radiotherapy. While it is important to note that various neurocognitive functions are interconnected throughout the brain, we can discern certain specialized roles of the hippocampi. The left hippocampus appears to play a predominant role in verbal memory, whereas the right hippocampus is associated more with visuospatial memory. Additionally, the anterior part of the hippocampus is more involved in episodic memory and emotional processing, while the posterior part is primarily responsible for spatial memory and pattern separation. Notably, a substantial body of evidence demonstrates a significant correlation between post-radiotherapy changes in the left hippocampus and subsequent cognitive decline in patients. In the context of individualized palliative radiotherapy, sparing the unilateral (specifically, the left, which is dominant in most individuals) hippocampus could expand the repertoire of strategies available for adapted WBRT in cases involving multiple brain metastases where stereotactic radiotherapy is not a viable option. Prospective ongoing studies assessing various memory-sparing radiotherapy techniques will define new standard of radiotherapy care of patients with multiple brain metastases.

Divergent thinking modulates interactions between episodic memory and schema knowledge: Controlled and spontaneous episodic retrieval processes.

The ability to generate novel ideas, known as divergent thinking, depends on both semantic knowledge and episodic memory. Semantic knowledge and episodic memory are known to interact to support memory decisions, but how they may interact to support divergent thinking is unknown. Moreover, it is debated whether divergent thinking relies on spontaneous or controlled retrieval processes. We addressed these questions by examining whether divergent thinking ability relates to interactions between semantic knowledge and different episodic memory processes. Participants completed the alternate uses task of divergent thinking, and completed a memory task in which they searched for target objects in schema-congruent or schema-incongruent locations within scenes. In a subsequent test, participants indicated where in each scene the target object had been located previously (i.e., spatial accuracy test), and provided confidence-based recognition memory judgments that indexed distinct episodic memory processes (i.e., recollection, familiarity, and unconscious memory) for the scenes. We found that higher divergent thinking ability-specifically in terms of the number of ideas generated-was related to (1) more of a benefit from recollection (a controlled process) and unconscious memory (a spontaneous process) on spatial accuracy and (2) beneficial differences in how semantic knowledge was combined with recollection and unconscious memory to influence spatial accuracy. In contrast, there were no effects with respect to familiarity (a spontaneous process). These findings indicate that divergent thinking is related to both controlled and spontaneous memory processes, and suggest that divergent thinking is related to the ability to flexibly combine semantic knowledge with episodic memory.

Towards ubiquitous and nonintrusive measurements of brain function in the real world: assessing blink-related oscillations during simulated flight using portable low-cost EEG.

Blink-related oscillations (BRO) are newly discovered neurophysiological phenomena associated with spontaneous blinking and represent cascading neural mechanisms including visual sensory, episodic memory, and information processing responses. These phenomena have been shown to be present at rest and during tasks and are modulated by cognitive load, creating the possibility for brain function assessments that can be integrated seamlessly into real-world settings. Prior works have largely examined the BRO phenomenon within controlled laboratory environments using magnetoencephalography and high-density electroencephalography (EEG) that are ill-suited for real-world deployment. Investigating BROs using low-density EEG within complex environments reflective of the real-world would further our understanding of how BRO responses can be utilized in real-world settings. We evaluated whether the BRO response could be captured in a high-fidelity flight simulation environment using a portable, low-density wireless EEG system. The effects of age and task demands on BRO responses were also examined. EEG data from 30 licensed pilots (age 43.37 +/- 17.86, 2 females) were collected during simulated flights at two cognitive workload levels. Comparisons of signal amplitudes were undertaken to confirm the presence of BRO responses and mixed model ANOVAs quantified the effects of workload and age group on BRO amplitudes. Significant increases in neural activity were observed post-blink compared to the baseline period (p < 0.05), confirming the presence of BRO responses. In line with prior studies, results showed BRO time-domain responses from the delta band (0.5-4 Hz) consisting of an early negative peak followed by a positive peak post-blink in temporal and parietal electrodes. Additionally, task workload and age-related effects were also found, with observations of the enhancement of BRO amplitudes with older age and attenuation of BRO responses in high workloads (p < 0.05). These findings demonstrate that it is possible to capture BRO responses within simulated flight environments using portable, low-cost, easy-to-use EEG systems. Furthermore, biological and task salience were reflected in these BRO responses. The successful detection and demonstration of both task-and age-related modulation of BRO responses in this study open the possibility of assessing human brain function across the lifespan with BRO responses in complex and realistic environments.

Aging effects on the encoding/retrieval flip in associative memory: fMRI evidence from incidental contingency learning.

Associative memory is arguably the most basic memory function and therein constitutes the foundation of all episodic and semantic memory processes. At the same time, the decline of associative memory represents a core feature of age-related cognitive decline in both, healthy and pathological (i.e., dementia-related) aging. The neural mechanisms underlying age-related impairments in associative memory are still not fully understood, especially regarding incidental (i.e., non-intentional) learning. We investigated the impact of age on the incidental learning and memory retrieval of face-name combinations in a total sample of 46 young (N = 23; mean age = 23.39 years) and elderly (N = 22, mean age = 69.05 years) participants. More specifically, particular interest was placed in age-related changes in encoding/retrieval (E/R) flips, which denote a neural antagonism of opposed activation patterns in the same brain region during memory encoding and retrieval, which were assessed using fMRI. According to our hypothesis, the results showed a significant age-related decline in the retrieval performance in the old group. Additionally, at the neural level, we discovered an abolished E/R flip in the right anterior insula and a joint but reduced E/R flip activation magnitude in the posterior middle cingulate cortex in older subjects. In conclusion, the present findings suggest that the impaired neural modulation of the E/R flip in the right aIC might be a sensitive marker in the early detection of neural aging.

Long-range connections damage in white matter hyperintensities affects information processing speed.

White matter hyperintensities, one of the major markers of cerebral small vessel disease, disrupt the integrity of neuronal networks and ultimately contribute to cognitive dysfunction. However, a deeper understanding of how white matter hyperintensities related to the connectivity patterns of brain hubs at the neural network level could provide valuable insights into the relationship between white matter hyperintensities and cognitive dysfunction. A total of 36 patients with moderate to severe white matter hyperintensities (Fazekas score ≥ 3) and 34 healthy controls underwent comprehensive neuropsychological assessments and resting-state functional MRI scans. The voxel-based graph-theory approach-functional connectivity strength was employed to systematically investigate the topological organization of the whole-brain networks. The white matter hyperintensities patients performed significantly worse than the healthy controls in episodic memory, executive function and information processing speed. Additionally, we found that white matter hyperintensities selectively affected highly connected hub regions, predominantly involving the medial and lateral prefrontal, precuneus, inferior parietal lobule, insula and thalamus. Intriguingly, this impairment was connectivity distance-dependent, with the most prominent disruptions observed in long-range connections (e.g. 100-150 mm). Finally, these disruptions of hub connectivity (e.g. the long-range functional connectivity strength in the left dorsolateral prefrontal cortex) positively correlated with the cognitive performance in white matter hyperintensities patients. Our findings emphasize that the disrupted hub connectivity patterns in white matter hyperintensities are dependent on connection distance, especially longer-distance connections, which in turn predispose white matter hyperintensities patients to worse cognitive function.

Domain‐specific subtle cognitive decline associations with cerebrospinal fluid and plasma β‐amyloid and p‐tau Alzheimer’s disease biomarkers in cognitively unimpaired individuals

AbstractBackgroundPresence of Alzheimer’s disease (AD) core pathology, β‐amyloid (Aβ) and p‐tau, has been proven to impact cognitive function even in cognitively unimpaired (CU) individuals. Although the Aβ and p‐tau (AT) effect has been mainly associated with memory function, recent evidence (Tideman, P., 2022. Neurology) suggested that Aβ levels were associated independently of p‐tau with the cross‐sectional performance in executive functioning. The aim of the present study was to explore specific associations of cerebrospinal fluid (CSF) and plasma Aβ and p‐tau baseline levels with the longitudinal change in several cognitive domains in a sample of CU individuals at increased risk of AD.MethodWe analyzed the associations of baseline CSF Aβ42/40, and p‐tau181 as well as plasma Aβ42/40, and p‐tau231 levels, with domain‐specific cognitive changes 3 years after baseline in 337 CU participants from the ALFA+ study. We defined AT groups (A‐T‐, A+T‐, and A+T+) using CSF levels, and the A‐T‐ group’s baseline performance served as reference to compute z‐scores for Visual Processing, Semantic Fluency, Executive Functioning, Episodic Memory, and Attentional Processing. Delta scores were computed by subtracting baseline from follow‐up scores and then compared among AT groups by means of ANCOVAs. Multiple linear regressions were performed on the whole sample using CSF Aβ42/40, p‐tau181 and plasma Aβ42/40, p‐tau231 as predictors of change in cognitive function.ResultA+T+ individuals showed a significant decline in Executive Function (p = 0.005, Cohen’s d = 0.716), and Attentional Processing (p = 0.032, Cohen’s d = 0.563), but not in Episodic Memory (p = 0.334) when compared with A‐T‐ individuals. In the whole sample, CSF Aβ42/40 was associated independently of p‐tau181 with a decline in Semantic Fluency (β = 6.284, p = 0.013), Attentional Processing (β = 3.828, p = 0.020), and Episodic Memory (β = 3.513, p = 0.004). Plasma p‐tau231 levels were associated with a decline in Semantic Fluency (β = ‐0.413, p = 0.045). CSF p‐tau181 and plasma Aβ42/40 were not associated with cognitive changes.ConclusionExecutive Function and Attentional Processing were more sensitive than Episodic Memory in capturing the early subtle cognitive changes in CU individuals with underlying AD pathology. Attentional Processing was the only cognitive domain associated both with the status of AD biomarkers and with the effect of CSF Aβ levels independently of p‐tau.

Development of a remotely applied app‐based cognitive training for early Alzheimer’s disease

AbstractBackgroundCognitive training (CT) has been proposed to attenuate cognitive decline in early Alzheimer’s disease and can be administered remotely. Here, we describe the design and development of an adaptive app‐based CT to remotely train cognitive functions that are affected early in the course of Alzheimer’s disease. We furthermore present interim results of CT acceptance and adherence in a group of participants with subjective cognitive decline (SCD).MethodWe used the Unity Game Engine software and the programming language C# to design a CT app with 16 games that target AD‐typical impairments in episodic and semantic memory and spatial processing, including working memory tasks to facilitate transfer processes (Figure 1). During each training session three games (each 10 min) are played. The training is adaptive to ensure a constant level of challenge, i.e., players progress to higher levels when they win rounds and decrease to lower levels when they lose rounds. The broad range of tasks ensures continued motivation and adherence of the participants over a prolonged training period. We aimed to design the game interfaces and navigation as user‐friendly as possible to maximize usability. Via an integrated help button participants can furthermore ask for help during home training. CT adherence can be assessed remotely.ResultPreliminary results on adherence and game experience show that participants with SCD (n = 62) like the games (5.49±0.13) and are motivated to perform well (6.3±0.08), despite being challenged (5.84±0.09) (7‐point Likert scale). After a 10‐week CT intervention, cognitive improvement is rated at 4.94±0.24 and participants would recommend the CT to a friend at 7.01±0.37 (9‐point Likert scale). Moreover, they would recommend that the games should be played for 32±2.64 min per day. The drop‐out rate is very low (4.6%). At the time of AAIC we will present additional data on acceptance/adherence and feasibility.ConclusionRemotely administered app‐based CT is applicable in the home setting and successful in motivating participants with early AD, which is also reflected in high adherence rates and acceptability. Future research should extend app‐based interventions to also target individuals with advanced cognitive impairment and applications for use in care‐home settings.

Prestimulus alpha power signals attention to retrieval.

The human brain is in distinct processing modes at different times. Specifically, a distinction can be made between encoding and retrieval modes, which refer to the brain's state when it is storing new information or searching for old information, respectively. Recent research proposed the idea of a "ready-to-encode" mode, which describes a prestimulus effect in brain activity that signals (external) attention to encoding and predicts subsequent memory performance. Whether there is also a corresponding "ready-to-retrieve" mode in human brain activity is currently unclear. In this study, we examined whether prestimulus oscillations can be linked to (internal) attention to retrieval. We show that task cues to prepare for retrieval (or testing) in comparison with restudy of previously studied vocabulary word pairs led to a significant decrease of prestimulus alpha power just before the onset of word stimuli. Beamformer analysis localized this effect in the right secondary visual cortex (Brodmann area 18). Correlation analysis showed that the task cue-induced, prestimulus alpha power effect is positively related to stimulus-induced alpha/beta power, which in turn predicted participants' memory performance. The results are consistent with the idea that prestimulus alpha power signals internal attention to retrieval, which promotes the elaborative processing of episodic memories. Future research on brain-computer interfaces may find the findings interesting regarding the potential of using online measures of fluctuating alpha oscillations to trigger the presentation and sequencing of restudy and testing trials, ultimately enhancing instructional learning strategies.

The role of bodily self-consciousness in episodic memory of naturalistic events: an immersive virtual reality study

Recent studies suggest that the human body plays a critical role in episodic memory. Still, the precise relationship between bodily self-consciousness (BSC) and memory formation of specific events, especially in real-life contexts, remains a topic of ongoing research. The present study investigated the relationship between BSC and episodic memory (EM) using immersive virtual reality (VR) technology. Participants were immersed in an urban environment with naturalistic events, while their visuomotor feedback was manipulated in three within-subjects conditions: Synchronous, Asynchronous, and No-body. Our results show that asynchronous visuomotor feedback and not seeing one’s body, compared to synchronous feedback, decrease the sense of self-identification, self-location and agency, and sense of presence. Moreover, navigating in the Asynchronous condition had a detrimental impact on incidental event memory, perceptual details, contextual association, subjective sense of remembering, and memory consolidation. In contrast, participants in the No-Body condition were only impaired in egocentric spatial memory and the sense of remembering at ten-day delay. We discuss these findings in relation to the role of bodily self-representation in space during event memory encoding. This study sheds light on the complex interplay between BSC, sense of presence, and episodic memory processes, and strengthens the potential of embodiment and VR technology in studying and enhancing human cognition.