The hippocampus as the switchboard between perception and memory

Adaptive memory recall requires a rapid and flexible switch from external perceptual reminders to internal mnemonic representations. However, owing to the limited temporal or spatial resolution of brain imaging modalities used in isolation, the hippocampal-cortical dynamics supporting this process remain unknown. We thus employed an object-scene cued recall paradigm across two studies, including intracranial electroencephalography (iEEG) and high-density scalp EEG. First, a sustained increase in hippocampal high gamma power (55 to 110 Hz) emerged 500 ms after cue onset and distinguished successful vs. unsuccessful recall. This increase in gamma power for successful recall was followed by a decrease in hippocampal alpha power (8 to 12 Hz). Intriguingly, the hippocampal gamma power increase marked the moment at which extrahippocampal activation patterns shifted from perceptual cue toward mnemonic target representations. In parallel, source-localized EEG alpha power revealed that the recall signal progresses from hippocampus to posterior parietal cortex and then to medial prefrontal cortex. Together, these results identify the hippocampus as the switchboard between perception and memory and elucidate the ensuing hippocampal-cortical dynamics supporting the recall process.

Gray matter asymmetry in asymptomatic carotid stenosis

Even clinically “asymptomatic” carotid stenosis is associated with multidomain cognitive impairment, gray matter (GM) atrophy, and silent lesion. However, the links between them remain unclear. Using structural MRI data, we examined GM asymmetry index (AI) and white matter hyperintensity (WMH) in 24 patients with severe asymptomatic carotid stenosis (SACS), 24 comorbidity‐matched controls, and independent samples of 84 elderly controls and 22 young adults. As compared to controls, SACS patients showed worse verbal memories, higher WMH burden, and right‐lateralized GM in posterior middle temporal and mouth‐somatomotor regions. These clusters extended to pars triangularis, lateral temporal, and cerebellar regions, when compared with young adults. Further, a full‐path of WMH burden (X), GM volume (atrophy, M1), AI (asymmetry, M2), and neuropsychological variables (Y) through a serial mediation model was analyzed. This analysis identified that left‐dominated GM atrophy and right‐lateralized asymmetry in the posterior middle temporal cortex mediated the relationship between WMH burden and recall memory in SACS patients. These results suggest that the unbalanced hemispheric atrophy in the posterior middle temporal cortex is crucial to mediating relationship between WMH burden and verbal recall memories, which may underlie accelerated aging and cognitive deterioration in patients with SACS and other vascular cognitive impairment.

Reporting of Concussion Symptoms by a Nationwide Survey of United States Parents of Middle School Children

This cross-sectional study assessed concussion symptom knowledge of parents of middle school (MS) children (aged 10-15 years) through a free-response item that solicited concussion symptoms and compared findings to a pre-validated scale-based measure. A self-administered online questionnaire was sent to a panel of randomly selected United States residents who were recruited by a third-party company, aged ≥ 18 years, and identified as parents of MS children. Via a free-response item, parents listed what they believed were concussion symptoms. Multiple sections later, parents identified potential concussion symptoms via a scale measure, which featured 25 items (22 actual symptoms, three distractor symptoms) with three response options: yes, no, maybe. Free-response item responses were coded into specific symptoms. The 1062 eligible parents that provided complete data commonly identified the symptoms of dizziness (90.2%), blurred vision (87.4%), and balance problems (86.4%) on the scale-based measure. However, these and other symptoms were less commonly identified via the free-response item (dizziness: 44.4%; blurred vision: 16.5%; balance problems: 3.5%). Concussion symptoms commonly reported via the scale-based measure were reported less frequently within the free-response item. Future research must explore strategies to help clinicians working with parents and their children to measure and assess concussion symptom reporting and knowledge.

Does experiencing inattentional blindness for crime influence eyewitness recall?

Witnesses may not notice crimes occurring when their attention is elsewhere, which may affect their memory. In this study, 174 participants completed an attention-demanding task while viewing a video containing an assault. Whether participants noticed the assault or experienced inattentional blindness for it was assessed. Then, participants were exposed to post-event information (containing misinformation) before completing a cued-recall task under one of three recall instructions (free, forced, or no instruction). Most participants experienced inattentional blindness for the assault (65.5%), which had a negative effect on recall, regardless of recall instruction. Specifically, participants who experienced inattentional blindness were less confident, complete, and accurate, and were more likely to report misinformation, than participants who noticed the crime. Witnesses who experienced inattentional blindness reported that they relied purely on post-event information to answer some questions. The findings suggest that caution should be taken when interviewing witnesses who have not paid attention to a crime.

5 Years of Exercise Intervention Did Not Benefit Cognition Compared to the Physical Activity Guidelines in Older Adults, but Higher Cardiorespiratory Fitness Did. A Generation 100 Substudy

Background: Aerobic exercise is proposed to attenuate cognitive decline in aging. We investigated the effect of different aerobic exercise interventions and cardiorespiratory fitness (CRF) upon cognition throughout a 5-year exercise intervention in older adults. Methods: 106 older adults (52 women, age 70-77 years) were randomized into high-intensity interval training (HIIT; ∼90% peak heart rate), moderate-intensity continuous training (MICT; ∼70% peak heart rate), or control for 5 years. The HIIT and MICT groups performed supervised training twice weekly, while the control group was asked to follow the national physical activity guidelines (30 min of physical activity/day). At baseline, 1-, 3-, and 5-year follow-up, participants partook in cognitive testing (spatial memory, verbal memory, pattern separation, processing speed, working memory, and planning ability), underwent clinical testing, and filled out health-related questionnaires. Linear mixed models were used to assess the effects of the exercise group and CRF (measured as peak and max oxygen uptake) on each cognitive test. The effects of changes in CRF on changes in each cognitive test score throughout the intervention were also assessed. The associations between baseline CRF and cognitive abilities at the follow-ups were investigated using linear regressions. Results: There was no group-by-time interaction on the cognitive measures, and neither HIIT nor MICT participation was associated with better cognitive performance than control at any time point during the 5-year intervention. All groups increased their CRF similarly during the 1st year and subsequently declined back to baseline levels after 5 years. A higher CRF was associated with higher processing speed throughout the intervention while increasing CRF during the intervention was associated with better working memory and worse pattern separation. Higher CRF at baseline predicted consistently better processing speed and verbal memory performance. Conclusion: In this first 5-year randomized controlled trial investigating the effects of HIIT, MICT, and physical activity according to national guidelines on cognition, we observed no effect of exercise intervention group on cognition when compared to following the national physical activity guidelines. Still, the results showed that higher CRF and increasing CRF benefited multiple, but not all, cognitive abilities in older adults. Clinical Trial Registration: www.ClinicalTrials.gov, identifier [NCT01666340].

Post-Traumatic Stress and Autobiographical Memory Accuracy in Young Children: Traumatic Events Versus Stressful and Pleasant Events

This study examined the influence of trauma exposure and posttraumatic stress (PTS) severity on accuracy of recall of autobiographical memory of traumatic events and pleasant events in very young children. Two hundred sixteen 3-6 year-old children with trauma exposure were interviewed with standardized interviews. Forty-one non-trauma-exposed controls were interviewed about stressful events for comparison. Accuracy of recall for both traumatic and pleasant events was not associated with severity of PTS. Trauma-exposed children showed significantly less accurate recall of trauma events compared to pleasant events. This difference was limited to children who experienced repeated trauma or Hurricane Katrina-related trauma experiences as opposed to single-blow types of trauma experiences. There was no difference in accuracy of recall of trauma events in the trauma-exposed group versus stressful events in the control group. There was also no difference in accuracy of recall of pleasant events between the trauma-exposed and the control groups. These findings do not support traditional theories that autobiographical recall is impaired in those with posttraumatic stress disorder or with trauma exposure. These findings demonstrate that very young children have access to and can verbalize accurate autobiographical recall of trauma events, which is important for clinical assessment and treatment.

On our susceptibility to external memory store manipulation: examining the influence of perceived reliability and expected access to an external store

Offloading memory to external stores (e.g., a saved file) allows us to evade the limitations of our internal memory. One cost of this strategy is that the external memory store used may be accessible to others and, thus, may be manipulated. Here we examine how reducing the perceived reliability of an external memory store and manipulating one's expectation for future access to such a store can influence participants' susceptibility to its manipulation (i.e., endorsing manipulated information as authentic). Across three pre-registered experiments, participants were able to store to-be-remembered information in an external store. On a critical trial, we surreptitiously manipulated the information in that store. Results demonstrated that an explicit notification of a previous manipulation of that store and the warning that the store will be inaccessible in the future can decrease susceptibility to manipulation of that store. Results are discussed in the context of the metacognitive monitoring and control of memory reports in situations that involve the distribution of memory demands across both internal and external spaces.

Memory: Neurobiological mechanisms and assessment

Memory is the process of retaining of knowledge over a period for the function of affecting future actions. It can be divided into declarative and procedural types. The process of memory consolidation is done in the hippocampus. The long-term memories are spread among various areas of the cerebrum depending on the different perceptual properties. The process of long-term potentiation and molecular changes occurring during memory formation are discussed in detail below. The steps involved in memory formation include encoding, storage, and recall (retrieval) in that order. Amnesia is a phenomenon in which there is the problem in memory formation which can be due to trauma to the brain, certain diseases, or stressors. While the assessment of memory has greatly improved, we are only beginning to understand the underlying mechanisms.

Olfaction-Related Factors Affecting Chemosensory Dream Content in a Sleep Laboratory

Mental activity in sleep often involves visual and auditory content. Chemosensory (olfactory and gustatory) experiences are less common and underexplored. The aim of the study was to identify olfaction-related factors that may affect the occurrence of chemosensory dream content. Specifically, we investigated the effects of all-night exposure to an ambient odour, participants' appraisal of their current olfactory environment, their general propensity to notice odours and act on them (i.e., odour awareness), and their olfactory acuity. Sixty pre-screened healthy young adults underwent olfactory assessment, completed a measure of odour awareness, and spent three nights in weekly intervals in a sleep laboratory. The purpose of the first visit was to adapt to the experimental setting. On the second visit, half of them were exposed to the smell of vanillin or thioglycolic acid and the other half to an odourless control condition. On the third visit, they received control or stimulation in a balanced order. On each visit, data were collected twice: once from the first rapid eye movement (REM) stage that occurred after 3 a.m., and then shortly before getting up, usually from a non-REM stage. Participants were asked to report the presence of sensory dream content and to assess their current olfactory environment. Neither exposure, nor participants' assessments of the ambient odour, or olfactory acuity affected reports of chemosensory dream content but they were more frequent in individuals with greater odour awareness. This finding may have implications for treatment when such experiences become unwanted or bothersome.

Evaluating the vaccination coverage: validity of household-hold vaccination booklet and caregiver's recall

BACKGROUND

We compared results from household data sources to medical record sources by using data from a vaccination coverage survey.

METHODS

Vaccination coverage (VC) was calculated based on parental recall, household vaccination booklet, and Zhejiang provincial immunization information system (ZJIIS). We evaluated the accuracy of VC based on household sources (vaccination booklet and recall) assuming the medical record was accurate. Concordance, sensitivity, specificity, positive predictive value, and negative predictive value were estimated as well as the Kappa statistic was also used to evaluate the agreement between data sources.

RESULTS

Among the 1,800 children identified in the household survey, all were registered in ZJIIS. VC estimated using the vaccination booklet alone was substantially lower than that based on medical records (net bias 3.4-16.7% in different age groups). VC based on parental recall ranged from 2.5% below (among children aged 1 year) to 16.7% points above (among children aged 6 years) than those based on medical records. Concordance was lowest for card estimates (32.5-45.5%). Sensitivity was <60% for all household sources, except for recall source. Specificity was lowest for recall estimates (14.5-42.6%). Positive predictive value was >75%, while negative predictive value was <50%, for all household sources. Kappa statistics generally indicated poor agreement between household and medical record sources.

CONCLUSIONS

Household-retained vaccination booklets and parental recall were insufficient sources for evaluating the VC. Our findings emphasized the importance of taking interventions to make the vaccination booklet more consistent with the records from medical resource.

The Effect of Forward Testing as a Function of Test Occasions and Study Material

It has long been known that one of the most effective study techniques is to be tested on the to-be-remembered material, a phenomenon known as the testing effect. Recent research has also shown that testing of previous materials promotes the learning of new materials, a phenomenon known as the forward testing effect. In this paper, as of yet unexplored aspects of the forward testing effect related to face-name learning are examined; continuous and initial testing are compared to restudying, the effects of an initial test on subsequent learning, and whether an initial change of domain (change from one topic to another) regarding study material affects the robustness of the effect. An experiment (N = 94) was performed according to a 2 (Material: word pairs/face-name pairs in Block 1) × 3 (Test occasions: Blocks 1–4/Blocks 1 and 4/Block 4) complex between-groups design. The results showed that no difference between testing and repetition could be observed regarding the recall of faces and names. The restudy groups incorrectly recalled more names from previous lists in the last interim test compared to the tested groups, which supports the theory that interim tests reduce proactive interference. The results also suggest that the number of test occasions correlates with the number of incorrect recalls from previous lists. These results, in contrast to previous studies, highlight a potential uncertainty about the forward testing effect linked to the robustness of the phenomenon, the specificity in execution, and generalizability.

Analysis of Emotion and Recall in COVID-19 Advertisements: A Neuroscientific Study

In this research, neuroscience techniques are applied to the field of marketing in the analysis of advertisements that include the COVID-19 pandemic in their stories. A study of emotion and memory in these audiovisual productions is carried out as two fundamental factors for the knowledge of consumer habits and decision making. By means of facial recognition biosensor systems (AFFDEX) and various tests, six informative and narrative, emotional and rational advertisements are presented to the subjects of the experiment to detect which emotions predominate; how they affect variables such as neuroticism, psychoticism or extroversion, among others; or what is remembered about the different works, brands and advertisers. Outstanding results are obtained in both emotional and cognitive analysis. Thus, in the field of public health, it is found that messages referring to COVID-19 included in advertisements are remembered more than other narratives or even the brands, products or services themselves. Likewise, joy is the predominant emotion, and its significance in such varied advertising stories stands out. Finally, it is clear that neuroscience research applied to marketing requires new methods and integrated applications to obtain satisfactory results in the advertising field.

[A feasibility study on cervical screening in non-attenders invited to undergo HPV self-sampling with cytology triage versus repeat invitation for cytology screening in Hokkaido]

Objectives　We investigated the participation and detection rates of cervical lesions in cervical screening non-attenders offered HPV (human papillomavirus) self-sampling with cytology triage.Methods　From 2016 to 2018, HPV self-sampling was routinely offered as an option, along with cytology, to all non-attenders in Ebetsu City, Japan. The primary endpoints were ≥CIN2 and ≥CIN3 detection rates, and secondary endpoints were abnormal cytology rates and follow-up compliance.Results　Overall, recall invitations were mailed to 6,116 non-attenders, with a response rate of 15.9% (cytology: 6.5%, HPV testing: 9.4%). Of the responders to undergo HPV self-sampling, 11.7% had a positive result and were referred to cytology triage. Moreover, ≥CIN2 and ≥CIN3 detection rates were 1.7% and 0.9%, respectively, in the HPV self-sampling group, and 1.0% and 0.8%, respectively, in the cytology group, showing no statistically significant differences. In those who underwent cytology triage following an HPV positive test, ≥CIN2 and ≥CIN3 detection rates were 23.8% and 11.9%, respectively, which was significantly higher than those who only underwent cytology alone.Conclusion　HPV self-sampling followed by cytology triage is highly effective at detecting high grade disease in non-attenders. Thus, multi-municipality-based studies to standardize processes involving this method are warranted. Furthermore, HPV self-sampling could be a promising method for inviting non-attenders who have difficulty undergoing cervical screening in the COVID-19 pandemic era.

Severe recalled labor pain and elective cesarean section in a subsequent delivery: a cohort study of Norwegian parous women

INTRODUCTION

Some women keep on recalling intense labor pain experienced at childbirth to a degree that may negatively affect their life during the postpartum period or lead them to request a cesarean section (CS) in the subsequent delivery. This longitudinal study aimed to assess the impact of severe recalled labor pain from the previous birth on the preference for and delivery by an elective CS in the subsequent delivery. Furthermore, we investigated whether co-occurring maternal demographic, somatic and mental health factors related to the previous and subsequent delivery, explain parts of a potential association.

MATERIAL AND METHODS

The study sample comprised 1135 parous women from the Akershus Birth Cohort. Severe recalled labor pain was assessed on a numeric rating scale at pregnancy week 17, and at pregnancy week 32, the preference for an elective CS for the subsequent delivery was assessed. Information on actual delivery by elective CS in the subsequent delivery was retrieved from the electronic birth record. Logistic regression analyses were conducted to examine the impact of severe recalled labor pain on elective CS.

RESULTS

Severe recalled labor pain at the previous birth was associated with a preference for an elective CS (odds ratio [OR] 3.57, 95% confidence interval [CI] 2.25-5.67) and actual delivery by elective CS (OR 4.71, 95% CI 2.32-9.59). This association remained statistically significant for the preference for an elective CS (adjusted OR [aOR] 2.12, 95% CI 1.24-3.62) but diminished for delivery by elective CS (aOR 2.30, 95% CI 0.99-5.35) when adjusting for a variety of covariates. Factors related to previous childbirth such as number of years since previous birth, assisted vaginal delivery, anal sphincter lesions, overall birth experience and fear of childbirth were also linked to preference for and delivery by an elective CS.

CONCLUSIONS

Women with severe recalled labor pain were about twice as likely to prefer an elective CS compared with women without severe recalled pain. For actual delivery, the significant association with severe recalled pain diminished after adjustment for covariates. However, sample size was small and, irrespective of severe recalled labor pain, preference for an elective CS was statistically significantly associated with actual delivery by elective CS.

Hippocampal ripples and their coordinated dialogue with the default mode network during recent and remote recollection

Hippocampal ripples are prominent synchronization events generated by hippocampal neuronal assemblies. To date, ripples have been primarily associated with navigational memory in rodents and short-term episodic recollections in humans. Here, we uncover different profiles of ripple activity in the human hippocampus during the retrieval of recent and remote autobiographical events and semantic facts. We found that the ripple rate increased significantly before reported recall compared to control conditions. Patterns of ripple activity across multiple hippocampal sites demonstrated remarkable specificity for memory type. Intriguingly, these ripple patterns revealed a semantization dimension, in which patterns associated with autobiographical contents become similar to those of semantic memory as a function of memory age. Finally, widely distributed sites across the neocortex exhibited ripple-coupled activations during recollection, with the strongest activation found within the default mode network. Our results thus reveal a key role for hippocampal ripples in orchestrating hippocampal-cortical communication across large-scale networks involved in conscious recollection.

Retrospective long-term analysis of tooth loss over 20 years in a specialist practice setting: Periodontally healthy/gingivitis and compromised patients

OBJECTIVE

To assess tooth loss (TL) in initially periodontally healthy/gingivitis (PHG) and periodontally compromised (PC) individuals during a 15- to 25-year follow-up in a specialist practice and to identify the factors influencing TL.

MATERIALS AND METHODS

Patients were re-examined 240 ± 60 months after active periodontal therapy (PC) or initial examination (PHG). PHG patients were periodontally healthy or had gingivitis, and PC patients exhibited at least stage II periodontitis. TL, patient-related outcomes, and risk factors for TL were assessed at the patient level (group-relation, gender, age, smoking, bleeding on probing, educational status, mean number of visits/year).

RESULTS

Fifty-six PC patients receiving regular supportive periodontal care (12 female, mean age 49.1 ± 10.9 years, stage II: 10, stage III/IV: 46) lost 38 teeth (0.03 ± 0.05 teeth/year). Fifty-one PHG patients (23 female, mean age 34.5 ± 12.4 years) following regular oral prevention lost 39 teeth (0.04 ± 0.05 teeth/year) (p = .631). Both PC and PHG groups did not show any significant differences regarding visual analogue scale measurements [aesthetics (p = .309), chewing function (p = .362), hygiene (p = .989)] and overall Oral Health Impact Profile (p = .484). Age at the start of follow-up was identified as a risk factor for TL (p < .0001).

CONCLUSION

PC and PHG patients exhibited similarly small TL rates over 240 ± 60 months, which should, however, be interpreted with caution in view of the group heterogeneity. Clinical trial number: DRKS00018840 (URL: https://drks.de).

The influence of thinking dispositions on integration and recall of multiple texts

We investigated the association between thinking dispositions and two outcomes of multiple‐texts comprehension: integration of conflicting information in argumentative essays; and recall of inferential information as an index of deep comprehension. We focused on two thinking dispositions, need for cognition (NFC) and actively open‐minded thinking (AOT), as relevant individual differences in the processes involved in multiple‐texts comprehension. NFC is the tendency to engage in and enjoy cognitively demanding activities, whereas AOT is the tendency to rationally evaluate arguments and supporting evidence, without being influenced by biases from one's own prior beliefs and prior knowledge. 73 university students completed perceived topic knowledge, perceived exposure to argumentative writing, and perceived competence in argumentative writing, NFC and AOT questionnaires, read two contradictory texts, wrote an argumentative essay, and recalled the information read 1 month later. Argumentative essays were assessed by length and level of integration of conflicting perspective. Text recalls were assessed by number of valid inferences included. Research questions were investigated through a path analysis model. The path analysis model had a good fit. NFC was indirectly associated with argumentation quality of the essay via the essay length. AOT was directly associated with the inferences included in the recall task. The present study contributes to the literature on multiple‐texts comprehension by emphasizing the role of thinking dispositions.

Two Faces of a Coin? A Systematic Review of Source Monitoring and Its Relationship with Memory in Autism

The ability to discriminate the origin of stimuli, known as source monitoring, is crucial for self–other distinction and the integration of internally generated and externally generated experiences. Despite its valence, evidence on source monitoring in autism is yet scarce and unclear. We systematically reviewed literature concerning source monitoring in autism and its relationship with other constructs, such as memory type, encoding effects, social cognition, general intelligence, and clinical factors. Source-monitoring performance (operationalized as error or accuracy) was reduced in autistic participants in 9 of the 15 studies that met the inclusion criteria. When explicitly investigated, free-recall memory impairments in autism were shown to influence source monitoring deficits. General intelligence was another important factor linked to source-monitoring performance. Conversely, other memory types or encoding effects were not impaired in autism, and no univocal association could be found with source monitoring. Social cognition and clinical symptoms were rarely assessed in spite of their possible involvement in source monitoring. The heterogeneity of the task design, outcome measures and demographical factors limited study comparability. As a research framework on source monitoring as a construct of primary interest in autism is still lacking, we propose preliminary indications for future investigations based on the collected findings.

The power of clinician-expressed empathy to increase information recall in advanced breast cancer care: an observational study in clinical care, exploring the mediating role of anxiety

OBJECTIVE

Experimental studies have found that clinician-expressed empathy improves patients' information recall in (advanced) cancer consultations. It remains unclear, however, whether these results are generalizable to clinical care and, if so, what the underlying mechanism is. We aimed to i) determine the relationship between clinician-expressed empathy and patients' information recall in clinical advanced breast cancer consultations; and ii) test whether the relationship between clinician-expressed empathy and recall is mediated by a decrease in patients' anxiety.

METHODS

Forty-one consultations between oncologists and female patients with advanced breast cancer were audio recorded. Patients' post-consultation information recall and pre- and post-consultation anxiety (0-100) were assessed. Recall was scored according to a self-created questionnaire. Clinician-expressed empathy (0-100) was assessed by observers. Structural Equation Modelling was used for all analyses.

RESULTS

Participants remembered 61% of the information discussed. Clinician-expressed empathy significantly increased patients' total information recall (p = .041) and recall of treatment aims/positive effects (p = .028). The mediating role of anxiety could not be established.

CONCLUSION

Although the underlying mechanism remains unclear, clinicians have a powerful tool to improve seriously ill breast cancer patients' recall of information: empathy.

PRACTICE IMPLICATIONS

These insights should encourage clinicians to express empathy; practical communication training might prove helpful.

REGION SPECIFIC AUTOMATIC QUALITY ASSURANCE FOR MRI-DERIVED CORTICAL SEGMENTATIONS

Quality control (QC) is a vital step for all scientific data analyses and is critically important in the biomedical sciences. Image segmentation is a common task in medical image analysis, and automated tools to segment many regions from human brain MRIs are now well established. However, these methods do not always give anatomically correct labels. Traditional methods for QC tend to reject statistical outliers, which may not necessarily be inaccurate. Here, we make use of a large database of over 12,000 brain images that contain 68 parcellations of the human cortex, each of which was assessed for anatomical accuracy by a human rater. We trained three machine learning models to determine if a region was anatomically accurate (as 'pass', or 'fail') and tested the performance on an independent dataset. We found good performance for the majority of labeled regions. This work will facilitate more anatomically accurate large-scale multi-site research.

Does self-focus orientation influence recall of autobiographical memories and subsequent mood in dysphoria?

Past research suggests that depressed individuals are less likely than non-depressed individuals to engage in mood-incongruent recall in response to negative mood and do not experience associated mood reparative effects. The present study examined the effects of adopting a reflective versus ruminative self-focus orientation towards one's mood on the valence of autobiographical memories recalled following a negative mood induction and the extent of mood repair following memory recall among individuals with varying depressive symptomatology. Participants underwent a negative mood induction and either a ruminative (n = 69) or reflective (n = 49) self-focus manipulation, and then recalled five specific autobiographical memories. Depression symptoms were associated with recall of less positive memories and reduced mood repair. The valence of recalled memories was associated with the extent of mood improvement, and depressive symptoms did not moderate this association. Contrary to our hypothesis, a reflective self-focus was not associated with recall of more positive memories or greater mood improvement than a ruminative self-focus. The results suggest that more depressed individuals are less likely to spontaneously engage in mood-incongruent recall in a negative mood state; however, recall of positive memories is associated with similar mood reparative effects regardless of depressive symptomatology.

Recognition memory for human motor learning

Motor skill retention is typically measured by asking participants to reproduce previously learned movements from memory. The analog of this retention test (recall memory) in human verbal memory is known to underestimate how much learning is actually retained. Here we asked whether information about previously learned movements, which can no longer be reproduced, is also retained. Following visuomotor adaptation, we used tests of recall that involved reproduction of previously learned movements and tests of recognition in which participants were asked whether a candidate limb displacement, produced by a robot arm held by the subject, corresponded to a movement direction that was experienced during active training. The main finding was that 24 h after training, estimates of recognition memory were about twice as accurate as those of recall memory. Thus, there is information about previously learned movements that is not retrieved using recall testing but can be accessed in tests of recognition. We conducted additional tests to assess whether, 24 h after learning, recall for previously learned movements could be improved by presenting passive movements as retrieval cues. These tests were conducted immediately prior to recall testing and involved the passive playback of a small number of movements, which were spread across the workspace and included both adapted and baseline movements, without being marked as such. This technique restored recall memory for movements to levels close to those of recognition memory performance. Thus, somatic information may enable retrieval of otherwise inaccessible motor memories.

Pain-dependent learning in healthy volunteers

A state-dependent learning paradigm was studied in which healthy adult volunteers studied/encoded and recalled information from short passages, neutral in their content, in one of the following conditions: (1) Pain during study-Pain during both recall sessions; (2) Pain during study-No Pain during both recall sessions; (3) No Pain during study-Pain during both recall sessions; and (4) No Pain during study-No Pain during both recall sessions. Pain was experimentally induced using the cold pressor technique. In this study, we looked at evidence for state-dependent learning when the context of learning is not emotionally driven, but neutral. The memory task consisted of encoding detailed information about short stories, then recalling as many details as possible 20 min and 48 hr later. The results indicated no occurrence of a state-dependent learning and retrieval effect in this sample: Participants in the pain-no pain and no pain-pain conditions did not significantly perform differently than participants in the pain-pain and no pain-no pain conditions. However, a main effect of the state during study/encoding was significant, suggesting that being in pain during study had a detrimental effect on performance on the memory tests regardless of the state at retrieval. These results oppose previous studies' findings and shed new light on possible implications in various research areas.

Biomarkers of memory variability in traumatic brain injury

Traumatic brain injury is a leading cause of cognitive disability and is often associated with significant impairment in episodic memory. In traumatic brain injury survivors, as in healthy controls, there is marked variability between individuals in memory ability. Using recordings from indwelling electrodes, we characterized and compared the oscillatory biomarkers of mnemonic variability in two cohorts of epilepsy patients: a group with a history of moderate-to-severe traumatic brain injury (n = 37) and a group of controls without traumatic brain injury (n = 111) closely matched for demographics and electrode coverage. Analysis of these recordings demonstrated that increased high-frequency power and decreased theta power across a broad set of brain regions mark periods of successful memory formation in both groups. As features in a logistic-regression classifier, spectral power biomarkers effectively predicted recall probability, with little difference between traumatic brain injury patients and controls. The two groups also displayed similar patterns of theta-frequency connectivity during successful encoding periods. These biomarkers of successful memory, highly conserved between traumatic brain injury patients and controls, could serve as the basis for novel therapies that target disordered memory across diverse forms of neurological disease.

The evolving view of replay and its functions in wake and sleep

The term hippocampal replay originally referred to the temporally compressed reinstantiation, during rest, of sequential neural activity observed during prior active wake. Since its description in the 1990s, hippocampal replay has often been viewed as the key mechanism by which a memory trace is repeatedly rehearsed at high speeds during sleep and gradually transferred to neocortical circuits. However, the methods used to measure the occurrence of replay remain debated, and it is now clear that the underlying neural events are considerably more complicated than the traditional narratives had suggested. “Replay-like” activity happens during wake, can play out in reverse order, may represent trajectories never taken by the animal, and may have additional functions beyond memory consolidation, from learning values and solving the problem of credit assignment to decision-making and planning. Still, we know little about the role of replay in cognition, and to what extent it differs between wake and sleep. This may soon change, however, because decades-long efforts to explain replay in terms of reinforcement learning (RL) have started to yield testable predictions and possible explanations for a diverse set of observations. Here, we (1) survey the diverse features of replay, focusing especially on the latest findings; (2) discuss recent attempts at unifying disparate experimental results and putatively different cognitive functions under the banner of RL; (3) discuss methodological issues and theoretical biases that impede progress or may warrant a partial revaluation of the current literature, and finally; (4) highlight areas of considerable uncertainty and promising avenues of inquiry.