Episodic Memory Research Articles

Asthma and Memory Function in Children

ImportanceAsthma is a chronic respiratory disease affecting approximately 5 million children in the US. Rodent models of asthma indicate memory deficits, but little is known about whether asthma alters children’s memory development.ObjectiveTo assess whether childhood asthma is associated with lower memory abilities in children.Design, Setting, and ParticipantsThis cohort study used observational data from the Adolescent Brain Cognitive Development (ABCD) Study, a multisite longitudinal investigation that began enrollment in 2015. Approximately 11 800 children aged 9 to 10 years were enrolled at baseline with follow-up at 1 and 2 years. Participants were selected based on exposures described subsequently to determine longitudinal and cross-sectional associations between asthma and memory. Data were analyzed from Month year to Month year.ExposuresAsthma was determined from parent reports. For the longitudinal analysis, children were selected if they had asthma at baseline and at the 2-year follow-up (earlier childhood onset), at the 2-year follow-up only (later childhood onset), or no history of asthma. For the cross-sectional analysis, children were selected if they had asthma at any time point, or no history of asthma. The comparison group of children with asthma history was matched on demographic and health covariates for each analysis.Main Outcomes and MeasuresThe primary outcome was episodic memory. Secondary outcomes included processing speed, inhibition and attention.ResultsFour hundred seventy-four children were included in the longitudinal analysis (earlier childhood onset: 135 children; mean [SD] age, 9.90 [0.63] years; 76 [56%] male; 53 [28%] Black, 29 [21%] Hispanic or Latino, and 91 [48%] White; later childhood onset: 102 children; mean [SD] age 9.88 [0.59] years; 54 [53%] female; 22 [17%] Black, 19 [19%] Hispanic or Latino, and 83 [63%] White; comparison: 237 children; mean [SD] age, 9.89 [0.59] years; 121 [51%] male; 47 [15%] Black, 48 [20%] Hispanic or Latino, and 194 [62%] White). Children with earlier onset of asthma exhibited lower rates of longitudinal memory improvements relative to the comparison group (β = −0.17; 95% CI, −0.28 to −0.05; P = .01). Two thousand sixty-two children were selected for the cross-sectional analysis (with asthma: 1031 children; mean [SD] age, 11.99 [0.66] years; 588 [57%] male; 360 [27%] Black, 186 [18%] Hispanic or Latino, and 719 [54%] White; without asthma: 1031 children; mean [SD] age 12.00 [0.66] years; 477 [54%] female; 273 [21%] Black, 242 [23%] Hispanic or Latino, and 782 [59%] White). Children with asthma (1031 children) showed lower scores on episodic memory (β = −0.09; 95% CI, −0.18 to −0.01; P = .04), processing speed (β = −0.13; 95% CI, −0.22 to −0.03; P = .01), and inhibition and attention (β = −0.11; 95% CI, −0.21 to −0.02; P = .02).Conclusions and RelevanceIn this cohort study, asthma was associated with memory difficulties in children, which may be more severe if asthma onset is earlier in childhood and may extend to executive function abilities.

Role of Cardiovascular Risk in Associations of Brain-Derived Neurotrophic Factor with Longitudinal Brain and Cognitive Trajectories in Older Adults

ABSTRACT Background Higher levels of brain-derived neurotrophic factor (BDNF) have been associated with better neurocognitive outcomes. BDNF is present in cardiovascular tissue, and some evidence suggests it may benefit cardiovascular function. The current study assessed whether there is a mediating and/or moderating role of cardiovascular health in the relationship between BDNF and brain and cognitive outcomes. Method We examined longitudinal data from 397 older adults (aged 54–89;164 females, 233 males) enrolled in the Alzheimer’s Disease Neuroimaging Initiative with available plasma BDNF, medical, neuroimaging, and cognitive assessments. We used path analysis and linear regression to estimate the mediating and moderating roles of two measures of cardiovascular health, the Framingham Risk Score (FRS) and pulse pressure, in the relationships between BDNF and longitudinal changes in brain structure (white matter hyperintensity volume, hippocampal volume, and primary visual cortex volume) and cognitive function (executive function, episodic memory, and language). Results There was no significant association of plasma BDNF with FRS or pulse pressure (ps > 0.31), precluding mediation. There were no robust associations between BDNF and longitudinal change in any brain structural or cognitive measures (ps > .12). Higher FRS was significantly associated with greater increases in WMH volume (ps < .01). FRS and pulse pressure were not associated with any other brain structural or cognitive outcomes (ps > .07). Conclusion These results suggest that cardiovascular health may not play an important role in the influence of BDNF on neurocognitive health in older adults.

A study of cognitive factor sequences and relations to creativity quality levels

Cognitive factors such as association, memory, and combination have been verified to be related to the creative design process. However, limited research has considered the effects of cognitive factors and their interaction on creative processes in practical creative design processes. This study aimed to detect the interactive effects of cognitive factors on creative processes in a practical creative design process. In particular, how the sequence of cognitive factors affects creativity quality levels of the creative solutions was investigated. Seventy-one participants were recruited to undertake a design task using the think-aloud method. The results of this study are as follows. (i) The sequences of cognitive factors can contribute to different creativity quality levels of solutions. The sequence of semantic memory, common association, remote association, episodic memory, remote combination, idea expression, and idea evaluation is more likely to lead to a higher creativity quality level of solutions. (ii) The repetition of the same cognitive factor in a creative design process, especially semantic memory, does not necessarily contribute to a high-creativity-quality-level solution. (iii) Creativity quality levels of solutions are related to how many cognitive factors categories are involved in the creative design process. The more cognitive factors included, the higher the creativity quality of the solutions will be.

The Contribution of the Face-Name Associative Recognition Test to Objectifying the Impairment of Associative Memory in Subjective Cognitive Decline

Objective: Subjective cognitive decline (SCD) is defined as a self-reported perception of cognitive decline that occurs without clear objective signs of cognitive impairment. There is still uncertainty in the literature about the reliability of SCD as an accurate indicator of the early stages of major neurocognitive disorders. Furthermore, objectifying cognitive impairment in SCD is difficult, mainly due to the insensitivity of the assessment instruments. The main objective of this study was to investigate the potential contribution of the face-name associative recognition test (FNART) to the objective identification of memory impairment in SCD. Method: A research sample of 69 adults with SCD and 69 healthy controls (HCs) recruited in the community were administered in the FNART, which included 32 photographs of neutral faces associated with 32 first names. Results: The total score of the HC group in the FNART was significantly better than that of the SCD group. Moreover, analyses based on the serial position of the stimuli showed that the SCD group performed significantly worse than the HC group only for the middle items (stimuli placed at the beginning or end of learning lists are more likely to be recalled than those presented in the middle), while no primacy and recency effects were found in the HCs. Conclusions: These findings indicate that associative episodic memory is more vulnerable in individuals with subjective cognitive decline (SCD) compared to those without cognitive complaints. Additionally, they suggest that the FNART may be effective in identifying cognitive decline in the preclinical stage of Alzheimer’s disease.

Oxygen supplementation and cognitive function in long-COVID.

Patients can experience persistent cognitive complaints and deficits in long-COVID. Inflammation and capillary damage may contribute to symptoms by interfering with tissue oxygenation. This was an exploratory pilot crossover study designed to describe the effects of supplemental oxygen (portable oxygen concentrator, POC) on cognitive performance and peripheral and cerebral oxygen saturation at rest and exercise. Participants with long-COVID (n = 21) were randomized 1:1 to: 1) POC (3h/day) for 2 weeks followed by standard of care (Control) for 2 weeks or 2) Control for 2 weeks then POC (3h/day) for 2 weeks, with a 1-week washout. Cognitive assessment (global cognition [Montreal Cognitive Assessment, MoCA], episodic memory [Hopkins], working memory [Digit Span], executive function [Verbal fluency]) was performed at baseline and after each treatment period. Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder-7 were completed. Peripheral and cerebral oxygen saturation were measured at rest and exercise (treadmill) at baseline and after each treatment period. Statistical analyses were descriptive without formal testing. MoCA scores were similar under POC (26.45±2.31) and Control (26.37±2.85); overall POC-Control difference was -0.090 (95% CI [-1.031, 0.850]). Because of a learning effect, post-hoc analyses were performed for Period 1, where the MoCA score difference was 1.705 [0.140, 3.271]. MoCA subscores suggested better performance with POC for Visuospatial/executive (0.618 [-0.106, 1.342]) and Attention (0.975 [0.207, 1.743]). POC trended to have better scores on Digit Span backward (difference: 0.822 [-0.067, 1.711]) and self-reported depressive symptoms (difference: -1.335 [-3.166, 0.495]). For specific PHQ-9 items, POC tended to have lower (better) scores for Q1 (Little interest/pleasure) and Q7 (Trouble concentrating). Cerebral oxygen saturations at end of exercise showed no difference between POC and Control. Peripheral saturations during exercise were similar under POC and Control (difference: 0.519% [-1.675, 2.714]). An advantage of POC over Control was observed for global cognition, attention, visuospatial/executive performance and depressive symptoms. Results need to be validated in a larger study.

Safety and Efficacy of Ashwagandha Root Extract on Cognition, Energy and Mood Problems in Adults: Prospective, Randomized, Placebo-Controlled Study.

This prospective, randomized, placebo-controlled study assessed the effects of Ashwagandha root extract (ARE) on cognition, energy, and mood in adults with self-reported cognitive and energy problems. Healthy subjects aged 30-75 years were randomized to receive ashwagandha (Withania somnifera) root extract (ARE) 600 mg/day (n = 60)/identical placebo (n = 60) orally for 8 weeks. Cognitive function was assessed at baseline and week 8 using a Computerized Mental Performance Assessment System (COMPASS). Secondary outcomes were Profile of Mood States Abbreviated Version (POMS-A), Mental Fatigue Scale (MFS) and Behavior Rating Inventory of Executive Function-Adult (BRIEF-A) for effects on mood, mental fatigue and executive function, respectively, assessed at baseline, week 4 and 8. Greater improvement (p < .05) from baseline scores were seen with ARE as against placebo for COMPASS items episodic memory, working memory and accuracy of attention. ARE also improved the POMS-A, MFS and BRIEF-A scores from baseline suggesting an improvement in mood, vigor, and an increase in the executive functioning respectively with ARE. The herb was well tolerated and had a good patient compliance with no serious adverse events reported in either of the groups. This study suggests that a dose of 600 mg a day can improve cognition, energy, and mood in adults with self-reported cognitive and energy problems.

Effects of home-based exercise alone or combined with cognitive training on cognition in community-dwelling older adults: A randomized clinical trial

BackgroundStructured and supervised physical exercise and cognitive training are two efficient ways to enhance cognition in older adults. Performing both within a combined intervention could maximize their effect on cognition due to their potential synergy on brain functions. During the COVID-19 pandemic, these interventions were particularly relevant due to the collateral impact of social restrictions regarding physical activity and the level of cognitive stimulation. However, the benefits of remotely monitored intervention combining physical exercise and cognitive training for older adult cognition remain to be demonstrated. Methods127 older adults (age: 65.20 ± 7.95) were randomized in two arms, encouraging self-engagement in six months of home-based physical exercise alone or combined with cognitive training, monitored by phone once a week. Neuropsychological assessment was performed under videoconference supervision at baseline and after three and six months. Composite Z-scores were calculated for processing speed, executive functioning, working, and episodic memory to assess changes after three and six months of training. The weekly metabolic expenditure of self-reported activities was estimated using the compendium of physical activity to distinguish participants performing higher and lower doses of exercise (median split). Results106 participants (83.46 %) completed the 6-month training. Results showed a greater Z-score change in executive functioning for participants in the combined arm than those who only exercised (F = 4.127, p = 0.046, ηp2 = 0.050). Group x Exercise dose interaction was observed for episodic memory Z-score change (F = 6.736, p = 0.011, ηp2 = 0.070), with a greater improvement for participants performing higher doses of exercise compared to those who performed a lower dose, only in exercise alone arm. Performing a higher dose of exercise increased the working memory Z-score change in both intervention arms compared to a lower dose (F = 7.391, p = 0.008, η p2 = 0.076). ConclusionRemote combined training may lead to larger improvement in executive functioning than exercise alone. Physical exercise showed a dose-related improvement in working and episodic memory performances. The combination of cognitive interventions mitigated the effects of exercise on episodic memory. These results suggest that home-based exercise and cognitive training may help improve older adults' cognition. Trial registrationCOVEPIC was retrospectively registered on December 03, 2020. Clinical trials Identifier: NCT04635462 - https://clinicaltrials.gov/ct2/show/record/NCT04635462?term=NCT04635462&draw=2&rank=1

Sensitive written hedgehog PICture Naming and Immediate Recall (PICNIR) as a valid and brief test of semantic and short-term episodic memory for very mild cognitive impairment.

Semantic and short-term episodic memory are impaired in some brain disorders including Alzheimer's disease. Development and validation of an almost self-administered, but cognitively demanding four-minute test identifying very mild cognitive impairment (vMCI). The innovative hedgehog PICture Naming and Immediate Recall (PICNIR) consisted of two parts. The first task was to write down the names of 20 black-and-white pictures to evaluate long-term semantic memory and language. The second task involves immediate recall and writing the names of as many previously named pictures as possible in one minute. The PICNIR is assessed using the number of naming errors (NE) and correctly recalled picture names (PICR). The PICNIR and a neuropsychological battery were administered to 190 elderly individuals living independently in the community. They were divided into those with vMCI (n = 43 with Montreal Cognitive Assessment (MoCA) 24 ± 3 points) and sociodemographically matched cognitively normal (CN) individuals (n = 147 with MoCA 26 ± 3). Both subgroups had predicted mean Mini-Mental State Examination scores of 28-29 points. Compared to CN, vMCI participants made more NE (0.3 ± 0.6 versus 0.6 ± 0.9; p = 0.02) and recalled fewer PICR (8.9 ± 2.2 versus 6.8 ± 2.2; p < 0.000001). Discriminative validity was satisfactory using the area under the ROC curve (AUC): 0.76 for PICR, 0.74 for MoCA, 0.67 for MoCA-five-word recall, and 0.59 for NE. The AUCs of PICR and MoCA were comparable and larger than those of MoCA five-point recall or NE. Logical Memory scores, RAVLT scores, Digit symbol, and animal fluency correlated with PICR. The picture-based PICNIR is an ultra-brief, sensitive cognitive test valid for assessing very mild cognitive impairment. Its effectiveness should be validated for other languages and cultures.

Remnant cholesterol and cognitive function: Evidence from the China health and retirement longitudinal study.

Evidence on associations of remnant cholesterol (RC) and its variability with cognitive function is still lacking. To explore the association of RC and its variability with cognitive function. Participants were recruited from a population-based cohort, the China Health and Retirement Longitudinal Study (CHARLS). Cognitive function was assessed by a standardized questionnaire from CHARLS, with domains of episodic memory and mental intactness. A linear mixed effects model was used to analyze the association of RC with cognitive function, along with its variability (calculated as standard deviation [SD], coefficient of variation [CV], variability independent of the mean [VIM]), with results expressed as β (95%CI). Potential subgroup differences in the association of RC and its variability with cognitive function were also explored. 4234 participants were eventually included, with mean (SD) age of 57.4 (8.0) years. Each 10 mg/dL increase in RC was associated with 0.053 (95%CI: 0.096, 0.009) points, 0.021 (95%CI: 0.042, 0.000) points, 0.032 (95%CI: 0.064, 0.001) points decrease in global cognitive function, episodic memory, and mental intactness scores, respectively. Compared with the first tertile (T1) group of RC variability (calculated as SD, VIM), T3 showed a lower level in global cognition and episodic memory after multivariate adjustment. The potential modification effects of educational level on RC and its variability in relation to cognitive function were also identified. Among Chinese middle-aged and older adults, higher RC level were associated with worse cognitive function. Greater RC variability was also associated with worse cognitive performance, especially in memory function.

Goal Shifts Structure Memories and Prioritize Event-defining Information in Memory.

Every day, we encounter far more information than we could possibly remember. Thus, our memory systems must organize and prioritize the details from an experience that can adaptively guide the storage and retrieval of specific episodic events. Prior work has shown that shifts in internal goal states can function as event boundaries, chunking experiences into distinct and memorable episodes. In addition, at short delays, memory for contextual information at boundaries has been shown to be enhanced compared with items within each event. However, it remains unclear if these memory enhancements are limited to features that signal a meaningful transition between events. To determine how changes in dynamic goal states influence the organization and content of long-term memory, we designed a 2-day experiment in which participants viewed a series of black-and-white objects surrounded by a color border on a two-by-two grid. The location of the object on the grid determined which of two tasks participants performed on a given trial. To examine if distinct types of goal shifts modulate the effects of event segmentation, we changed the border color, the task, or both after every four items in a sequence. We found that goal shifts influenced temporal memory in a manner consistent with the formation of distinct events. However, for subjective memory representations in particular, these effects differed by the type of event boundary. Furthermore, to examine if goal shifts lead to the prioritization of goal-relevant features in longer lasting memories, we tested source memory for each object's color and grid location both immediately and after a 24-hr delay. On the immediate test, boundaries enhanced the memory for all concurrent source features compared with nonboundary items, but only if those boundaries involved a goal shift. In contrast, after a delay, the source memory was selectively enhanced for the feature relevant to the goal shift. These findings suggest that goals can adaptively structure memories by prioritizing contextual features that define a unique episode in memory.

Alterations of Excitation-Inhibition Balance and Brain Network Dynamics Support Sensory Deprivation Theory in Presbycusis.

Sensory deprivation theory is an important hypothesis involving potential pathways between hearing loss and cognitive impairment in patients with presbycusis. The theory suggests that prolonged auditory deprivation in presbycusis, including neural deafferentation, cortical reallocation, and atrophy, causes long-lasting changes and reorganization in brain structure and function. However, neurophysiological changes underlying the cognition-ear link have not been explored. In this study, we recruited 98 presbycusis patients and 60 healthy controls and examined the differences between the two groups in gamma-aminobutyric acid (GABA) and glutamate (Glu) levels in bilateral auditory cortex, excitation-inhibition (E/I) balance (Glu/GABA ratio), dynamic functional network connectivity (dFNC), hearing ability and cognitive performance. Then, correlations with each other were investigated and variables with statistical significance were further analyzed using the PROCESS Macro in SPSS. GABA levels in right auditory cortex and Glu levels in bilateral auditory cortex were lower but E/I balance in right auditory cortex were higher in presbycusis patients compared to healthy controls. Hearing assessments and cognitive performance were worse in presbycusis patients. Three recurring connectivity states were identified after dFNC analysis: State 1 (least frequent, middle-high dFNC strength with negative functional connectivity), State 2 (high dFNC strength), and State 3 (most frequent, low dFNC strength). The occurrence and dwell time of State 3 were higher, on the other hand, the dwell time of State 2 decreased in patients with presbycusis compared to healthy controls. In patients with presbycusis, worse hearing assessments and cognition were correlated with decreased GABA levels, increased E/I balance, and aberrant dFNC, decreased GABA levels and increased E/I balance were correlated with decreased occurrence and dwell time in State 3. In the mediation model, the fractional windows, as well as dwell time in State 3, mediated the relationship between the E/I balance in right auditory cortex and episodic memory (Auditory Verbal Learning Test, AVLT) in presbycusis. Moreover, in patients with presbycusis, we found that worse hearing loss contribute to lower GABA levels, higher E/I balance, and further impact aberrant dFNC, which caused lower AVLT scores. Overall, the results suggest that a shift in E/I balance in right auditory cortex plays an important role in cognition-ear link reorganization and provide evidence for sensory deprivation theory, enhancing our understanding the connection between neurophysiological changes and cognitive impairment in presbycusis. In presbycusis patients, E/I balance may serve as a potential neuroimaging marker for exploring and predicting cognitive impairment.

Movement boosts memory: Investigating the effects of acute exercise on episodic long-term memory

Long-term memory is important for cognitive health across the lifespan. Previously research has indicated that a bout of exercise improves memory retention for approximately one week; however, its prolonged effects are unknown. This study investigated the effects of acute moderate-intensity exercise on long-term memory for 11 months. Participants engaged in the exercise intervention and seated rest control condition, followed by a word encoding memory task. Word retention in the exercise intervention was better than in the control condition at 6- and 8-weeks post-encoding. These findings suggest that exercise before encoding enhances long-term episodic memory recall for at least eight weeks.

Medial Temporal Lobe Damage Impairs Temporal Integration in Episodic Memory.

Although the role of the medial temporal lobe (MTL) and the hippocampus in episodic memory is well established, there is emerging evidence that these regions play a broader role in cognition, specifically in temporal processing. However, despite strong evidence that the hippocampus plays a critical role in sequential processing, the involvement of the MTL in timing per se is poorly understood. In the present study, we investigated whether patients with MTL damage exhibit differential performance on a temporal distance memory task. Critically, we manipulated context shifts, or boundaries, which have been shown to interfere with associative binding, leading to increases in subjective temporal distance. We predicted that patients with MTL damage would show impaired binding across boundaries and thus fail to show temporal expansion. Consistent with this hypothesis, unilateral patients failed to show a temporal expansion effect, and bilateral patients actually exhibited the reverse effect, suggesting a critical role for the MTL in binding temporal information across boundaries. Furthermore, patients were impaired overall on both the temporal distance memory task and recognition memory, but not on an independent, short-timescale temporal perception task. Interestingly, temporal distance performance could be independently predicted by performance on recognition memory and the short temporal perception task. Together, these data suggest that distinct mnemonic and temporal processes may influence long interval temporal memory and that damage to the MTL may impair the ability to integrate episodic and temporal information in memory.

Time after Time: Preserving Temporal Memories When Experiences Repeat.

Remembering when events occur in time is fundamental to episodic memory. Yet, many experiences repeat over time creating the potential for interference when attempting to recall temporally specific memories. Here, we argue that temporal memories are protected, in part, by reinstatement of temporal context information that is triggered by stimulus repetitions. We motivate this argument by integrating seminal findings across several distinct literatures and methodologies. Specifically, we consider key insights from foundational behavioral studies of temporal memory, recent electrophysiological and neuroimaging approaches to measuring memory reinstatement, and computational models that describe how temporal context representations shape memory processes. We also note several open questions concerning how temporal context reinstatement might influence subsequent temporal memory, including potential mediating effects of event spacing and event boundaries. These ideas and questions have the potential to guide future research and, ultimately, to advance theoretical accounts of how we preserve temporal memories.

Building and Breaking the Chain: A Model of Reward Prediction Error Integration and Segmentation of Memory.

Prediction errors drive reinforcement learning and organize episodic memory into distinct contexts, but do these effects interact? Here, we review the roles of midbrain dopamine, the locus coeruleus, and the hippocampus in event cognition to propose and simulate the theoretical influence of two prediction error signals in integrating versus segmenting events in memory. We suggest that signed reward prediction errors can build mental models of reward environments, increasing the contextual similarity (integration) of experiences with stronger, more stable reward expectations. On the other hand, unsigned reward prediction errors can signal a new model of the environment, generating a contextual shift (segmentation) between experiences that crossed them. We moreover predicted that these differences in contextual similarity give rise to distinct patterns of temporal-order memory. We combined these ideas in a computational model to account for a seemingly paradoxical pattern of temporal-order memory where greater representational distance helps order memory within context but impairs it across contexts. We found that simulating signed reward prediction error integration and unsigned reward prediction error segmentation differentially enabled the model to perform associative chaining, which involved reactivating items between two tested probes to assist with sequential retrieval. In summary, our simulations provide a unifying explanation for the varied ways that neuromodulatory systems may alter event cognition and memory.

Cognitive development: Sudden integration of abstract concepts in a hippocampal map

The mechanisms responsible for the late development of episodic memories are still elusive. A new study shows that the sudden improvement of memory performance during development is paralleled by the integration, by hippocampal neurons, of abstract information about the task.

Cognition-related connectome gradient dysfunctions of thalamus and basal ganglia in drug-naïve first-episode major depressive disorder

BackgroundSubcortical functional abnormalities are believed to contribute to clinical symptoms and cognitive impairments in major depressive disorder (MDD). By introducing functional gradient mapping, the present study evaluated subcortical gradients in MDD patients and their association with cognitive features. MethodsOrganization patterns and between-group differences in the principal subcortical gradient were investigated in 145 never-treated first-episode MDD patients and 145 healthy controls (HCs) across limbic, thalamic, and basal ganglia (BG) systems and their structural and functional subregions. We also assessed the associations between significant gradient alterations and clinical characteristics and neuropsychological functioning. ResultsOverall, MDD patients showed a relatively compressed and disturbed gradient organization than HCs, with limbic and BG regions located at the two extreme ends of the principal gradient. Specifically, MDD patients had lower principal gradient values in thalamus and limbic system but higher values in BG than HCs. These gradient alterations, associated with intrinsic Euclidian distance and functional connectivity patterns, manifested as spatial rearrangements of gradient values within each respective subregion. Lower gradient values in thalamic subregion projecting to default mode network were associated with higher principal gradient values in BG subregion projecting to ventral attention network, and these gradient alterations were correlated with poorer episodic memory performance in MDD patients. LimitationsThe specific neuropathological mechanisms driving the gradient alterations still require further investigation. ConclusionsOpposing gradient alterations in the thalamic and BG regions synergistically impact episodic memory performance in MDD, revealing an internally differentiated and cognition related pattern of subcortical gradient dysfunction in MDD.

The Working Memory Model and the relationship between immediate serial recall and immediate free recall.

The effects of speech-based variables on the immediate serial recall (ISR) task constitute fundamental evidence underpinning the concept of the Phonological Loop component of Working Memory. Somewhat surprisingly, the Phonological Loop has yet to be applied to the immediate free recall (IFR) task although both tasks share similar memoranda and presentation methods. We believe that the separation of theories of ISR and IFR has contributed to the historical divergence between the Working Memory and Episodic Memory literature. We review more recent evidence showing that the two tasks are approached by participants in similar ways, with similar encoding and rehearsal strategies, and are similarly affected by manipulations of word length, phonological similarity, articulatory suppression/concurrent articulation, and irrelevant speech/sound. We present new analyses showing that the outputs of the two tasks share similar runs of successive items that include the first and last items- which we term start- and end-sequences, respectively-that the remaining residual items exhibit strong recency effects, and that start- and end-sequences impose constraints on output order that help account for error transposition gradients in ISR. Such analyses suggest that similar mechanisms might convey serial order information in the two tasks. We believe that recency effects are often under-appreciated in theories of ISR, and IFR mechanisms could generate error transpositions. We hope that our review and new analyses encourage greater theoretical integration between ISR and IFR and between the Working Memory and Episodic Memory literature.

Exploring the Development of Past and Future Episodic Memory in Adolescents with Autism Spectrum Disorder: A Preliminary Longitudinal Study

Adolescence is a critical period where individuals build their identity and consolidate how they interact with others. However, for adolescents with autism spectrum disorder (ASD), the development of identity and social bounds is at stake. These challenges with the development of identity and social bonds could be linked to difficulties in autobiographical memory (AM), whether recalling past events (past episodic memory; past EM) or imagining future scenarios (episodic future thinking; EFT). To date, developmental patterns of AM over time remain poorly understood in ASD. Eleven adolescents with ASD or typical development (TD) completed an assessment of past EM and EFT once per year for three years. Preliminary results show that past EM becomes more detailed over the years for adolescents with ASD, while there is no change for TD adolescents. Interestingly, only the content elements of the narrated events are increasing, not the context elements. Furthermore, EFT evolves in the TD group but remains stable in the ASD group. This first multi-case longitudinal study of AM needs to be replicated with more participants, but it seems to indicate a heterogeneous evolution of AM in ASD. For future studies, these results will lead us to explore the hypothesis of developmental delay and the factors influencing AM development in ASD. Finally, understanding these developmental pathways highlights the importance of personalized therapeutic approaches to support social integration, identity construction, and future projects for adolescents with ASD.

Spatially resolved transcriptomic signatures of hippocampal subregions and Arc-expressing ensembles in active place avoidance memory

The rodent hippocampus is a spatially organized neuronal network that supports the formation of spatial and episodic memories. We conducted bulk RNA sequencing and spatial transcriptomics experiments to measure gene expression changes in the dorsal hippocampus following the recall of active place avoidance (APA) memory. Through bulk RNA sequencing, we examined the gene expression changes following memory recall across the functionally distinct subregions of the dorsal hippocampus. We found that recall induced differentially expressed genes (DEGs) in the CA1 and CA3 hippocampal subregions were enriched with genes involved in synaptic transmission and synaptic plasticity, while DEGs in the dentate gyrus (DG) were enriched with genes involved in energy balance and ribosomal function. Through spatial transcriptomics, we examined gene expression changes following memory recall across an array of spots encompassing putative memory-associated neuronal ensembles marked by the expression of the IEGs Arc, Egr1, and c-Jun. Within samples from both trained and untrained mice, the subpopulations of spatial transcriptomic spots marked by these IEGs were transcriptomically and spatially distinct from one another. DEGs detected between Arc + and Arc− spots exclusively in the trained mouse were enriched in several memory-related gene ontology terms, including “regulation of synaptic plasticity” and “memory.” Our results suggest that APA memory recall is supported by regionalized transcriptomic profiles separating the CA1 and CA3 from the DG, transcriptionally and spatially distinct IEG expressing spatial transcriptomic spots, and biological processes related to synaptic plasticity as a defining the difference between Arc + and Arc− spatial transcriptomic spots.