Arabic verbal fluency in mesial temporal and generalized epilepsy: evidence from letter and category tasks with healthy controls.

A central challenge in cognitive neuroscience is to explain how semantic and episodic memory - two major forms of declarative memory, typically associated with cortical and hippocampal processing - interact to support learning, recall, and imagination. Despite significant advances, we still lack a unified computational framework that jointly accounts for core empirical phenomena across both semantic and episodic processing domains. Here, we introduce the Generative Episodic-Semantic Integration System (GENESIS), a computational model that formalizes memory as the interaction between two limited-capacity generative systems: a Cortical-VAE, supporting semantic learning and generalization, and a Hippocampal-VAE, supporting episodic encoding and retrieval within a retrieval-augmented generation (RAG) architecture. GENESIS reproduces hallmark behavioral findings - including generalization in semantic memory, recognition, serial recall effects and gist-based distortions in episodic memory, and constructive episodic simulation - while capturing their dynamic interactions. The model elucidates how capacity constraints shape the fidelity and memorability of experiences, how semantic processing introduces systematic distortions in episodic recall, and how episodic replay can recombine previous experiences. Together, these results provide a principled account of memory as an active, constructive, and resource-bounded process. GENESIS thus advances a unified theoretical framework that bridges semantic and episodic memory, offering new insights into the generative foundations of human cognition.

Numerous episodic memory research studies have shown that young adults use self-initiated intentional strategies to encode verbal stimuli and that self-initiated intentional encoding strategy use plays a significant role in memory performance. However, the types, frequency, and effectiveness of self-initiated intentional memory retrieval strategies that young adults use during free recall of verbal stimuli from episodic memory have not been systematically investigated. The goals of this study were to (a) systematically examine the types and frequency of self-initiated intentional memory retrieval strategies that young adults use to recall individually presented unrelated words and to (b) investigate whether use of self-initiated intentional memory retrieval strategies during free recall could benefit memory for individually presented unrelated words in addition to use of self-initiated intentional memory strategies during encoding. Young adults intentionally encoded individually presented unrelated words, completed a free recall memory assessment, and made retrospective open-ended and frequency rating scale encoding and retrieval strategy reports. Several types of self-initiated intentional memory retrieval strategies were reported. Ninety-seven and one hundred percent of participants reported using at least one self-initiated systematic intentional memory retrieval strategy in their open-ended and frequency rating scale strategy reports, respectively. Participants reported using individual self-initiated intentional memory retrieval strategies to try to recall 10%-59% of words on average. Self-reported use of concept imagery and sentence generation retrieval strategies predicted free recall when controlling for self-reported use of concept imagery and sentence generation encoding strategies, suggesting that use of self-initiated intentional memory retrieval strategies could benefit verbal episodic memory. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Effects of novelty and reward-based fear extinction on memory generalization.

Single-neuron recordings from the medial temporal lobe of patients undergoing epilepsy surgery have revealed "concept cells" that respond selectively and invariantly to meaningful stimuli such as specific people, places, or objects. These responses offer a unique window into how individual neurons encode high-level, multimodal representations-the building blocks of episodic memory-that differ from the more distributed, often hierarchical representations supporting semantic memory in the neocortex. Episodic and semantic memory, the systems for storing past experiences and conceptual knowledge, have traditionally been regarded as distinct. However, converging evidence from neuroimaging, lesion studies, and electrophysiological recordings challenges this strict dichotomy. This review synthesizes findings from human single-neuron recordings to re-examine the traditional distinction between episodic and semantic memory. We propose that the primary difference between the two systems lies in the structure of the associations they support: sparse, arbitrary links supporting episodic memory in the hippocampus versus ordered, hierarchical representations supporting semantic memory in the neocortex.

Effects of pistachio consumption on cognition, cardiometabolic risk factors, and life satisfaction in older adults: Protocol for a remote-based randomized controlled trial.

Recent evidence has suggested an association between high sodium intake and development of cognitive impairment. However, while animal studies demonstrate consistent relationships between sodium intake and cognitive impairment, this relationship remains less clear in humans. Our aim was to investigate the relationship between self-reported baseline sodium intake and cognitive decline over 72 months. Cognitively unimpaired participants (n = 1208) from the Australian Imaging, Biomarkers and Lifestyle study were included (70.87 years of age; 41 % male). Participants completed a food frequency questionnaire to quantify sodium intake and underwent comprehensive neuropsychological assessment at baseline and four additional timepoints, 18 months apart. Scores for six cognitive composite domains were generated. Linear mixed models examined associations between baseline sodium intake and cognitive decline including potential confounders in the cohort as a whole and when stratified by sex and Apolipoprotein E status. Following false discovery rate adjustment, there was a negative association between sodium intake and change in the episodic recall composite in males (β=-0.00002; SE=0.00001; FDR adjusted p = 0.044), such that males with higher sodium intake showed faster decline in episodic recall. No associations were observed in the cohort as a whole or in females. No associations were observed when the cohort was stratified by Apolipoprotein E status. Further investigation, including sex-specific approaches, is required to evaluate how sodium intake could be incorporated as one modifiable lifestyle factor aimed at delaying Alzheimer's disease onset.

What episodic memory reveals about the default mode network

The mental timeline is used as a memory strategy.

The hippocampus has a critical role in the online processing of information; encoding, storage, and retrieval of episodic memory; and novelty detection. These functions have been classically associated with a trisynaptic circuit connecting the entorhinal cortex, the dentate gyrus, area CA3, and area CA1. Until recently, the role of area CA2, located between CA3 and CA1, has been underappreciated. However, increased evidence indicates that, despite its small size,1 area CA2 has a critical role in in regulating activity throughout the hippocampal circuit and has a unique importance in social recognition memory.2-8 Area CA2 has widespread connectivity with other hippocampal regions2 and has unique structural features, electrophysiologic responses, pattens of receptor expression, and subcortical inputs. Pyramidal CA2 neurons are more resistant to excitotoxicity than those in other hippocampal subfields.9 However, area CA2 is susceptible to accumulation of alpha-synuclein10,11 and tau.12 Experimental studies show loss or impaired function of a critical subpopulation of local inhibitory CA2 interneurons in several disorders, including temporal lobe epilepsy,13 Alzheimer disease (AD), multiple sclerosis, schizophrenia, and autism spectrum disorder.14.

Alzheimer's disease (AD) neuropathology starts decades before clinical manifestations, but the early indicators of AD in midlife remain unclear. Functional segregation of brain networks is a key marker of brain health. It remains unknown, however, whether inherited risk of AD impacts network segregation from midlife in individuals who are cognitively healthy but carry inherited risk for late-life AD. To address this question, we investigate which brain networks show the strongest age-related segregation loss in the Cam-CAN lifespan cohort (18-88 years, N = 652), and whether APOE ε4 genotype impacts segregation of age-vulnerable networks in the midlife PREVENT cohort (40-59 years, N = 210), cross-sectionally and longitudinally. Higher-order networks showing the most significant age-related decline are the default mode (DMN), frontal-parietal control (FPN) and salience (SN) networks. Cognitively healthy midlife APOE ε4 carriers have higher segregation across the brain cross-sectionally, accompanied by greater longitudinal decline in the DMN over two years, relative to non-carriers. Higher DMN segregation is associated with better episodic and relational memory across the PREVENT cohort. These findings suggest that functional segregation may serve as a potential biomarker, providing insights into the mechanisms through which APOE influences brain function and cognition from healthy midlife, on average 23 years before dementia onset.

The NIH Toolbox Cognition Battery (NIHTB-CB) has shown promising results in older adult populations, though more research is needed to examine its relationship with important clinical outcomes (i.e. everyday function, depression). Particularly, additional research on potential disparities in self vs. informant reports in these outcomes is of importance. The aim of the present study was to examine the NIHTB-CB's relationship with both self and informant-reported everyday functioning and depression in older adults. Forty-three cognitively healthy older adults completed the NIHTB-CB. Participants and their informants completed questionnaires related to the participants' everyday functioning (Everyday Cognition Scale; ECog) and depression (Geriatric Depression Scale-30; GDS-30). Correlation between NIHTB-CB, ECog, and GDS-30 was conducted. Then, simultaneous regression analyses of total ECog controlling for GDS-30 and significant NIHTB-CB scores identified in the prior aim were conducted. Worse performance on NIHTB-CB tests of processing speed, working memory (WM), inhibitory control, and conceptual flexibility (CF) were all related to worse self-reported everyday functioning and greater depression (all p < 0.05). Further, associations between WM and CF remained significantly associated with worse everyday functioning even after accounting for self-reported depression. While NIHTB-CB episodic memory was associated with informant-rated participant depression, there was no association of any NIHTB-CB measures with informant-rated everyday functioning. The NIHTB-CB is associated with functional changes in cognitively healthy older adults and may be useful in early identification of risk for a pathological cognitive aging trajectory. Further exploration of informant-reported participant depression in cognitive aging is warranted.

During navigation, the brain builds representations of self-motion and of environmental information for future action. The classic view suggests that these representations consolidate and eventually stabilize. However, there are no data on their fate at extended memory delays. Here we investigated memory of real-world navigational episodes across memory delays of up to three decades. We show that memory of the spatial aspects of these episodes do not achieve a stable state but rather continue to transform for many years. Our data suggest that at any given point in time, spatial memory of navigational episodes is a changing combination of episode-independent schematic information and several interacting spatial representations directly related to a navigational episode, which may show distinct temporal trajectories. Consistent with recent accounts of memory reorganization, we further show that neither current theories of systems consolidation nor classic models of forgetting fully explain spatial memory performance at extended memory delays.

Childhood adversity is a known risk factor for psychopathology across the lifespan. One proposed mechanism involves long-term alterations in hippocampal memory systems, leading to disruptions in the integration of episodic memory within its contextual framework. It is therefore essential to investigate how individuals exposed to early life stress use contextual information during memory formation. We conducted an experimental study in healthy adults (n = 76), manipulating the depth of contextual encoding. Participants viewed object-background pairs under either contextual or object-focused conditions, followed by a surprise memory test assessing object recognition and mnemonic discrimination. Childhood adversity was measured using the Childhood Trauma Questionnaire. Contrary to our initial hypothesis, contextual elaboration did not enhance recognition performance, but appeared to increase cognitive demands during encoding. We propose that increased contextual processing shifted attentional allocation away from object-specific information, thereby limiting recognition performance. Differences in recognition outcomes across conditions may further reflect variations in the strength and discriminative value of familiarity-based memory signals under differing encoding demands. We additionally observed a descriptive association between higher levels of childhood adversity and reduced object recognition performance under object-focused encoding conditions. These findings suggest that associations between childhood adversity and memory performance may emerge in a task-dependent manner and can be situated within broader theoretical accounts emphasizing the role of contextual factors in episodic memory implicated in vulnerability to mental health outcomes following early life stress.

Major depressive disorder is known to disturb the hippocampus, but how this impacts signal processing performed by the structure remains poorly understood. Here, we report that single housing (7-10 days) promotes a depression-like phenotype in young adult mice that is associated with a robust, yet surprisingly discreet defect in information flow across the primary hippocampal circuit. In addition to sociability disturbances and despair-like behavior, single housing eliminated preference for novelty and impaired episodic memory encoding. Additionally, the lateral habenula, an epithalamic structure critically involved in depression, was hyperactive. Although the CA1 waveform and associated spike output elicited by single-pulse lateral perforant path (LPP) activation of hippocampus was largely unaffected by single housing, pronounced disturbances emerged when the circuit was activated with physiologically relevant frequencies and patterns. The characteristic 'theta/gamma' pattern was distorted such that a pronounced facilitation was present in the single-housed group, while the filtering of CA1 output to brief beta (25 Hz) and gamma (50 Hz) frequency LPP stimulation evident in group-housed slices was absent. Within field CA3, the recruitment of inhibitory interneurons suppresses spike output, and subsequent signal propagation to CA1, in response to beta frequency LPP inputs but not those arriving at gamma frequencies. This CA3 beta filter was significantly impaired following single housing. These results suggest that a depression phenotype is associated with a highly selective and partial loss of inhibition within the CA3 and CA1 links of the hippocampal circuit, providing new insights into the relationship between depression and hippocampal function.

Neural Correlates of Metamemory Judgments in Worry: An ERP Study.

Introduction Aging, cardiorespiratory fitness, and habitual physical activity influence thermoregulation and cognition, yet their combined impact during prolonged extreme heat exposure is not well understood. This study investigated how these factors influence thermal strain and cognitive performance across the adult lifespan under extreme heat stress. Methods Sixty-one participants (27 females; 20-79 years) wore an accelerometer for seven days, completed a graded exercise test to determine peak oxygen uptake (V̇O2peak), and underwent a six-hour heat exposure (43°C, 25% humidity) with episodic exercise to simulate daily living tasks. Rectal (Tre) and skin temperature, heart rate, whole-body sweat rate and cognitive performance (episodic memory, executive function, attention, processing speed) were measured. Time, age, V̇O2peak, moderate-vigorous physical activity (MVPA) level and sex were entered into linear mixed effects models (mean [95% CI]). Results Advancing age exacerbated the rise of Tre (per decade: 0.08°C [0.04,0.13], P<0.01) and reduced whole-body sweating (per decade: -6 g·m-2·h-1 [-10,-1], P<0.01). Cognitive performance reduced with advancing age, independent of heat exposure (P<0.01). Higher cardiorespiratory fitness improved whole-body sweat rate (per 10 mL·kg-1·min-1: 11 g·m-2·h-1 [2,19], P=0.01) and reduced end-exposure heart rate (per 10 mL·kg-1·min-1: -4 beats·min-1 [-8,-1], P=0.03). Weekly MVPA and sex showed minimal association with outcome variables. Conclusion Across adulthood, advancing age exacerbated the rise in Tre and lowered whole-body sweating during a six-hour extreme heat exposure. Cardiorespiratory fitness improved whole-body sweating but did not offset age-related increases in Tre. Therefore, physiological strain during extreme heat exposure develops progressively across the lifespan, with cardiorespiratory fitness moderating, but not preventing, age-related susceptibility.

The effects of repetitive transcranial magnetic stimulation over the lateral parietal region on episodic future thinking and episodic memory.

Episodic memory is critically dependent on the hippocampal network and is frequently impaired in many clinical disorders. Recent findings highlight Hippocampal Indirectly Targeted Stimulation (HITS) as a promising, network-guided non-invasive transcranial magnetic stimulation (TMS) procedure to enhance episodic memory performance. Here, we report the first comprehensive meta-analysis of HITS effects on episodic memory, encompassing both healthy individuals and clinical populations. HITS using parieto-occipital network targets robustly improved episodic memory, with effects selective for episodic memory versus other non-memory cognitive domains. Efficacy was significantly greater when memory performance was assessed using memory tasks sensitive to recollection, which is strongly linked to hippocampal network function, compared to recognition or other types of episodic memory tasks. Efficacy was also significantly greater when HITS was delivered before the memory tasks were administered versus in the period between study and test phases of tasks. No serious adverse events were reported. These findings establish HITS as a robust approach for episodic memory enhancement, suggesting potential for clinical translation in memory disorders. Selectivity of effects for episodic memory generally and for recollection-format tests in particular indicates cognitive and mechanistic specificity, supporting the potential for targeted and selective neuromodulation of hippocampal networks and their associated functions.

Remembering what you did: Episodic memory for self-actions.