Retention Of Task Research Articles

Unlocking the Potential: Semaglutide's Impact on Alzheimer's and Parkinson's Disease in Animal Models.

Semaglutide (SEM), a glucagon-like peptide-1 receptor agonist, has garnered increasing interest for its potential therapeutic effects in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). This review provides a comprehensive description of SEM's mechanism of action and its effects in preclinical studies of these debilitating conditions. In animal models of AD, SEM has proved beneficial effects on multiple pathological hallmarks of the disease. SEM administration has been associated with reductions in amyloid-beta plaque deposition and mitigation of neuroinflammation. Moreover, SEM treatment has been shown to ameliorate behavioral deficits related to anxiety and social interaction. SEM-treated animals exhibit improvements in spatial learning and memory retention tasks, as evidenced by enhanced performance in maze navigation tests and novel object recognition assays. Similarly, in animal models of PD, SEM has demonstrated promising neuroprotective effects through various mechanisms. These include modulation of neuroinflammation, enhancement of mitochondrial function, and promotion of neurogenesis. Additionally, SEM has been shown to improve motor function and ameliorate dopaminergic neuronal loss, offering the potential for disease-modifying treatment strategies. Overall, the accumulating evidence from preclinical studies suggests that SEM holds promise as a novel therapeutic approach for AD and PD. Further research is warranted to elucidate the underlying mechanisms of SEM's neuroprotective effects and to translate these findings into clinical applications for the treatment of these devastating neurodegenerative disorders.

Short-term retention of popular music in older adults: Support for a plasticity theory of implicit music knowledge acquisition

Based on our Plasticity Theory of Implicit Music Knowledge Acquisition (PTIMKA), we tested the hypothesis that adolescence is a sensitive period for acquiring musical information and lifelong musical grammar. Older adults (N = 27, mean age = 65.7 years; SD = 6.7) identified artist, title, and year of popularity and rated their familiarity for short excerpts of 36 songs popular between 1962 and 2021. Knowledge and familiarity were greater for music popular during the participants’ adolescence. A subsequent surprise retention task required participants to choose which of 2 excerpts had been presented in the first task; for each of 36 trials, targets and foils represented the same era of popularity. Retention (dꞌ) scores and confidence in retention judgment were higher for the songs popular during adolescence, even though targets of all eras had just been presented in the previous 15 minutes. It is argued that popular music styles congruent with an adolescence-established grammar were more accurately encoded than styles violating this grammar, as would songs popular before or after adolescence. Prior data from younger adults showing trajectories opposite to those for older adults as a function of decade of popularity are further consistent with this interpretation and with PTIMKA. (Work supported by NSERC)

A two-stage deep-learning framework for CT denoising based on a clinically structure-unaligned paired data set.

In low-dose computed tomography (LDCT) lung cancer screening, soft tissue is hardly appreciable due to high noise levels. While deep learning-based LDCT denoising methods have shown promise, they typically rely on structurally aligned synthesized paired data, which lack consideration of the clinical reality that there are no aligned LDCT and normal-dose CT (NDCT) images available. This study introduces an LDCT denoising method using clinically structure-unaligned but paired data sets (LDCT and NDCT scans from the same patients) to improve lesion detection during LDCT lung cancer screening. A cohort of 64 patients undergoing both LDCT and NDCT was randomly divided into training (n=46) and testing (n=18) sets. A two-stage training approach was adopted. First, Gaussian noise was added to NDCT data to create simulated LDCT data for generator training. Then, the model was trained on a clinically structure-unaligned paired data set using a Wasserstein generative adversarial network (WGAN) framework with the initial generator weights obtained during the first stage of training. An attention mechanism was also incorporated into the network. Validated on a clinical CT data set, our proposed method outperformed other available methods [CycleGAN, Pixel2Pixel, block-matching and three-dimensional filtering (BM3D)] in noise removal and detail retention tasks in terms of the peak signal-to-noise ratio (PSNR), structural similarity index measure (SSIM), and root mean square error (RMSE) metrics. Compared with the results produced by BM3D, our method yielded an average improvement of approximately 7% in terms of the three evaluation indicators. The probability density profile of the denoised CT output produced using our method best fit the reference NDCT scan. Additionally, our two-stage model outperformed the one-stage WGAN-based model in both objective and subjective evaluations, further demonstrating the higher effectiveness of our two-stage training approach. The proposed method performed the best in removing noise from LDCT scans and exhibited good detail retention, which could potentially enhance the lesion detection and characterization effects obtained for soft tissues in the scanning scope of LDCT lung cancer screening.

Transfer of learning in histology: Insights from a longitudinal study.

All anatomical educators hope that students apply past training to both similar and new tasks. This two-group longitudinal study investigated the development of such transfer of learning in a histology course. After 0, 10, and 20 sessions of the 10-week-long course, medical students completed theoretical tasks, examined histological slides trained in the course (retention task), and unfamiliar histological slides (transfer task). The results showed that students in the histology group gradually outperformed the control group in all tasks, especially in the second half of the course, η2 = 0.268 (p < 0.001). The best predictor of final transfer performance was students' retention performance after 10 sessions, β = 0.32 (p = 0.028), and theoretical knowledge after 20 sessions, β = 0.46 (p = 0.003). Results of eye tracking methodology further revealed that the histology group engaged in greater "visual activity" when solving transfer tasks, as indicated by an increase in the total fixation count, η2 = 0.103 (p = 0.014). This longitudinal study provides evidence that medical students can use what they learn in histology courses to solve unfamiliar problems but cautions that positive transfer effects develop relatively late in the course. Thus, course time and the complex relationship between theory, retention, and transfer holds critical implications for anatomical curricula seeking to foster the transfer of learning.

Comparison between verbal and visual working memory in subjects with frontotemporal dementia and Alzheimer’s participating in the Redlat study

AbstractBackgroundAlterations in working memory have been reported in people with Alzheimer’s disease and frontotemporal degeneration, and have been associated with executive impairment related to the frontal areas of the brain.MethodThe objective of this work is to compare the capacity of verbal and visual working memory in a sample of 70 Colombian people with dementia (32 with Alzheimer’s Dementia and 30 with Frontotemporal Dementia and 22 healthy controls) participating in the RedLat study. For this, the performance in a digit retention task and the Short Term Memory Binding Test (STMB) are studied.ResultIn general, there is a decrease in the performance of the two groups of patients (AD and FTD). Also AD patients shows worst performance at visual working memory tasks. Results shows differences between dementia groups and controls, but not between AD and FTD.ConclusionThis converges with what has been reported about the dissociation between verbal and visual working memory, and could suggest alternative strategies for the recall of immediate information. Additionally, both low performances are explained by differents reasons in each neurodegenerative disorder.

Sustainability in virtual education: A case study of virtual university of Pakistan

The penetration of technology has helped in better online learning and training around the world by minimizing the time and space issues coupled with traditional education and training. Regardless of the several benefits, keeping students on online platforms is an arduous task. Taking the case study of the Virtual University of Pakistan, this paper explores the impact of personal and environmental factors on online Leaner’s intention to continue through satisfaction. Primary data was gathered from 361 students of 3 regional campuses through a self-administrated closed-ended questionnaire. Partial Least Squares Structural Equation Modeling (PLS-SEM) was used to analyze the data in SmartPLS software. The study results indicate that only the provision of satisfying personal and environmental factors by distance learning higher education institutions can help them in attracting and retaining students. The post-COVID-19 situation has made the student intake and retention task even harder as the traditional education institution has also built the capabilities to provide online education and diminishing the niche market of virtual education institutions.

Memory retention following acoustic stimulation in slow-wave sleep: a meta-analytic review of replicability and measurement quality

The role of slow oscillations and spindles during sleep on memory retention has become an area of great interest in the recent decade. Accordingly, there are multiple studies that examine the efficacy of acoustic stimulation during sleep to facilitate slow oscillations and associated memory retention. Here, we run meta-analyses on a current set of 14 studies that use audible noise-burst sound stimulation to modulate overnight retention of word pairs (kS = 12 studies, kES = 14 effect sizes, n = 206 subjects). Our meta-analyses demonstrate a steady, yearly decline in effect size that accounts for 91.8% of the heterogeneity between studies. We find that the predicted effect on memory retention in 2013 favored the acoustic stimulation condition at dδ = 0.99 (95% CI [0.49, 1.49]), while the predicted effect in 2021 declined to a moderate and significant effect favoring no acoustic stimulation at dδ = −0.39 (95% CI [−0.73, −0.05]). Our meta-regression model finds no coded study-level characteristics could account for the decline in effect sizes over time other than the publication date alone. Using available data, we estimate that 34% of subjects are not actually blind to the acoustic stimulation condition due to hearing acoustic stimulation during sleep. In addition, we find that the test-retest reliability of memory retention scores is nearly zero (ρd = 0.01, 95% CI [−0.18, 0.21]), and through simulation demonstrate the impact this has on statistical power and observed effect sizes. Based on our analyses, we discuss the need for larger sample sizes, true placebo controls, age range restrictions, open-data sharing, and improvements in the reliability of memory retention tasks.

Increased cognitive load in immersive virtual reality during visuomotor adaptation is associated with decreased long-term retention and context transfer

BackgroundComplex motor tasks in immersive virtual reality using a head-mounted display (HMD-VR) have been shown to increase cognitive load and decrease motor performance compared to conventional computer screens (CS). Separately, visuomotor adaptation in HMD-VR has been shown to recruit more explicit, cognitive strategies, resulting in decreased implicit mechanisms thought to contribute to motor memory formation. However, it is unclear whether visuomotor adaptation in HMD-VR increases cognitive load and whether cognitive load is related to explicit mechanisms and long-term motor memory formation.MethodsWe randomized 36 healthy participants into three equal groups. All groups completed an established visuomotor adaptation task measuring explicit and implicit mechanisms, combined with a dual-task probe measuring cognitive load. Then, all groups returned after 24-h to measure retention of the overall adaptation. One group completed both training and retention tasks in CS (measuring long-term retention in a CS environment), one group completed both training and retention tasks in HMD-VR (measuring long-term retention in an HMD-VR environment), and one group completed the training task in HMD-VR and the retention task in CS (measuring context transfer from an HMD-VR environment). A Generalized Linear Mixed-Effect Model (GLMM) was used to compare cognitive load between CS and HMD-VR during visuomotor adaptation, t-tests were used to compare overall adaptation and explicit and implicit mechanisms between CS and HMD-VR training environments, and ANOVAs were used to compare group differences in long-term retention and context transfer.ResultsCognitive load was found to be greater in HMD-VR than in CS. This increased cognitive load was related to decreased use of explicit, cognitive mechanisms early in adaptation. Moreover, increased cognitive load was also related to decreased long-term motor memory formation. Finally, training in HMD-VR resulted in decreased long-term retention and context transfer.ConclusionsOur findings show that cognitive load increases in HMD-VR and relates to explicit learning and long-term motor memory formation during motor learning. Future studies should examine what factors cause increased cognitive load in HMD-VR motor learning and whether this impacts HMD-VR training and long-term retention in clinical populations.

Response Time Modulates the Relationship Between Implicit Learning and Motor Ability in Children With and Without Autism Spectrum Disorders: A Preliminary Study.

Difficulty with implicit learning plays an important role in the symptomology of autism spectrum disorder (ASD). However, findings in motor learning are inconsistent. This study evaluated implicit sequence learning and its relationship with motor ability in children with and without ASD. We adopted a classic serial reaction time task with a retention task and three awareness tests. The Movement Assessment Battery for Children was administered to assess children's motor ability. Significant learning differences between children with and without ASD were only found in retention but not immediately after the serial reaction time task. These findings suggest that the impaired implicit learning in ASD is characterized as impaired consolidation where the relatively permanent changes are missing. Exploratory moderation analyses revealed a significant relationship between implicit learning and motor ability for individuals with faster response time. We argue the importance of response speed for optimal learning and should be weighted more for future intervention in children with ASD.

Potential Benefits of Daytime Naps on Consecutive Days for Motor Adaptation Learning.

Daytime napping offers benefits for motor memory learning and is used as a habitual countermeasure to improve daytime functioning. A single nap has been shown to ameliorate motor memory learning, although the effect of consecutive napping on motor memory consolidation remains unclear. This study aimed to explore the effect of daytime napping over multiple days on motor memory learning. Twenty university students were divided into a napping group and no-nap (awake) group. The napping group performed motor adaption tasks before and after napping for three consecutive days, whereas the no-nap group performed the task on a similar time schedule as the napping group. A subsequent retest was conducted one week after the end of the intervention. Significant differences were observed only for speed at 30 degrees to complete the retention task, which was significantly faster in the napping group than in the awake group. No significant consolidation effects over the three consecutive nap intervention periods were confirmed. Due to the limitations of the different experimental environments of the napping and the control group, the current results warrant further investigation to assess whether consecutive napping may benefit motor memory learning, which is specific to speed.

Influence of noise manipulation on retention in a simulated ICU ward round: an experimental pilot study

BackgroundNoise exposure leads to a reduction in cognitive abilities in diverse settings, however, only limited data exist examining the effects of environmental ICU noise on the cognitive performance of ICU professionals. A frequently occurring and demanding retention task in ICUs are ward rounds, which are considered key for the provision of medical care. Here, we investigate the influence of noise on information retention in a simulated ward round.MethodsICU professionals were exposed to a recorded, ICU ward round, simulated partly with and partly without environmental ICU noise. Ward rounds were followed by specific questions about previously provided information.Results56 ICU professionals (aged 26–59 years) were included. A logistic mixed model showed a reduction of 27% (P < 0.001) in the ward round test performance when participants were exposed to environmental ICU noise. Furthermore, advanced age was associated with reduced retention (− 28%, P < 0.001), questions containing important information performed better (+ 36%, P < 0.001), and higher stress led to better performance in retention (+ 24%, P = 0.01).ConclusionsOur data showed a considerable negative influence of environmental ICU noise during a simulated ward round. Therefore, reduction of environmental ICU noise is recommended. The influence of additional factors, including stress, priorities, and demographic factors should be pursued in subsequent investigations.

Neuroprotective Effects of Poria cocos (Agaricomycetes) Essential Oil on Aβ1-40-Induced Learning and Memory Deficit in Rats.

Alzheimer's disease (AD) is a neurodegenerative disease that has become a leading cause of death in recent years. The present study aimed to explore the possible prophylactic effects of Poria cocos essential oil (PCEO) against memory deficits in Aβ rats. Adult male Wistar rats were given Aβ1-42 via ICV injection. The effect of 30 d administration of PCEO by oral gavage was investigated. Novel object recognition (NOR) test, Morris water maze (MWM) test, and passive avoidance memory retention (PAM) task were performed. Aβ decreased the cognitive memory in NOR, spatial memory in MWM, and passive avoidance memory in PAM tests. In contrast, PCEO improved learning and memory in the treated group. The PCEO treatment halts the activity of AChE in the hippocampus and cortex of the AD rats. The central neuronal degeneration in Aβ-injected rats was not only ascertained by the histopathological changes but also confirmed indirectly by the concomitant increase in GFAP immunostaining. The beneficial effects in AD of increasing cellular GPx, GR, CAT, Na+ K+ ATPase and GST through the administration of PCEO may not only result in protection against neurodegeneration but also result in improvement in cognitive function. PCEO may be recommended as a prophylactic and/or adjunct medication for neurodegenerative diseases.

Gender Diversity in Computer Science at a Large Public R1 Research University: Reporting on a Self-study

With the number of jobs in computer occupations on the rise, there is a greater need for computer science (CS) graduates than ever. At the same time, most CS departments across the country are only seeing 25–30% of women students in their classes, meaning that we are failing to draw interest from a large portion of the population. In this work, we explore the gender gap in CS at Rutgers University–New Brunswick, a large public R1 research university, using three data sets that span thousands of students across six academic years. Specifically, we combine these data sets to study the gender gaps in four core CS courses and explore the correlation of several factors with retention and the impact of these factors on changes to the gender gap as students proceed through the CS courses toward completing the CS major. For example, we find that a significant percentage of women students taking the introductory CS1 course for majors do not intend to major in CS, which may be a contributing factor to a large increase in the gender gap immediately after CS1. This finding implies that part of the retention task is attracting these women students to further explore the major. Results from our study include both novel findings and findings that are consistent with known challenges for increasing gender diversity in CS. In both cases, we provide extensive quantitative data in support of the findings.

Connecting explanations to representations: benefits of highlighting techniques in tutorial videos on students’ learning in organic chemistry

ABSTRACT Research in science education agrees that one of the key challenges of learners in the discipline is certainly connecting domain-specific representations to the underlying concepts. One way of supporting students to make applicable connections is using purposefully designed highlighting techniques in multimedia instructions. In order to examine the influence of different highlighting techniques on learning, 171 chemistry undergraduate students were provided with tutorial videos either with static, dynamic or without highlighting. The results show that students viewing tutorial videos with dynamic highlighting gave more sophisticated answers in direct retention tasks. Furthermore, results indicate that low prior knowledge is compensated by both static and dynamic highlighting techniques. This finding is supported by causal mediation analysis, which indicates that the effect of prior knowledge is moderated by the different highlighting techniques. Besides student learning outcomes, students’ evaluation of the different tutorial videos shows significant benefits of the highlighted instructions in terms of perceiving higher comprehensibility. The results support the use of appropriate highlighting techniques in instructional formats to foster a stronger link between conceptual knowledge and representations.

Temporally distinct oscillatory codes of retention and manipulation of verbal working memory.

Most psychophysiological studies of working memory (WM) target only the short-term memory construct, whereas short-term memory is only a part of the WM responsible for the storage of sensory information. Here, we aimed to further investigate oscillatory brain mechanisms supporting the executive components of WM-the part responsible for the manipulation of information. We conducted an exploratory reanalysis of a previously published EEG dataset where 156 participants (82 females) performed tasks requiring either simple retention or retention and manipulation of verbal information in WM. A relatively long delay period (>6s) was employed to investigate the temporal trajectory of the oscillatory brain activity. Compared with baseline, theta activity was significantly enhanced during encoding and the delay period. Alpha-band power decreased during encoding and switched to an increase in the first part of the delay before returning to the baseline in the second part; beta-band power remained below baseline during encoding and the delay. The difference between the manipulation and retention tasks in spectral power had diverse temporal trajectories in different frequency bands. The difference maintained over encoding and the first part of the delay in theta, during the first part of the delay in beta, and during the whole delay period in alpha. Our results suggest that task-related modulations in theta power co-vary with the demands on the executive control network; beta suppression during mental manipulation can be related to the activation of motor networks; and alpha is likely to reflect the activation of language areas simultaneously with sensory input blockade.

Blast-induced hearing loss suppresses hippocampal neurogenesis and disrupts long term spatial memory

Acoustic information transduced by cochlear hair cells is continuously relayed from the auditory pathway to other sensory, motor, emotional and cognitive centers in the central nervous system. Human epidemiological studies have suggested that hearing loss is a risk factor for dementia and cognitive decline, but the mechanisms contributing to these memory and cognitive impairments are poorly understood. To explore these issues in a controlled experimental setting, we exposed adult rats to a series of intense blast wave exposures that significantly reduced the neural output of the cochlea. Several weeks later, we used the Morris Water Maze test, a hippocampal-dependent memory task, to assess the ability of Blast Wave and Control rats to learn a spatial navigation task (memory acquisition) and to remember what they had learned (spatial memory retention) several weeks earlier. The elevated plus maze and open field arena were used to test for anxiety-like behaviors. Afterwards, hippocampal cell proliferation and neurogenesis were evaluated using bromodeoxyuridine (BrdU), doublecortin (DCX), and Neuronal Nuclei (NeuN) immunolabeling. The Blast Wave and Control rats learned the spatial navigation task equally well and showed no differences on tests of anxiety. However, the Blast Wave rats performed significantly worse on the spatial memory retention task, i.e., remembering where they had been two weeks earlier. Deficits on the spatial memory retention task were associated with significant decreases in hippocampal cell proliferation and neurogenesis. Our blast wave results are consistent with other experimental manipulations that link spatial memory retention deficits (long term memory) with decreased cell proliferation and neurogenesis in the hippocampus. These results add to the growing body of knowledge linking blast-induced cochlear hearing loss with the cognitive deficits often seen in combat personnel and provide mechanistic insights into these extra auditory disorders that could lead to therapeutic interventions.

Preference-Performance Dissociation in Golf Putting.

The purpose of the current study was to examine the effectiveness of providing autonomy to learners and the phenomenon of preference-performance dissociation on a closed, self-paced motor task – putting in golf, when using different placements of a visual aid (a large circle) around a golf hole. Seventy-six participants were assigned to four experimental groups: (a) a visual aid placed behind the hole (V-behind group), (b) a visual aid placed in front of the hole (V-in-front group), (c) a visual aid placed around the hole (V-around group), and (d) a visual aid placed according to the participant’s preference (V-pref group). Participants performed five pre-trials, 50 training putts from a distance of 2 m, a retention task (12 putts) from a distance of 2 m, and a transfer task (12 putts) from a distance of 2.5 m. The retention putts and transfer putts were performed 48 h after the training putts. The participants’ subjective assessment of the helpfulness of the circle was also measured. It was found that in the retention task, putting consistency was lower in the V-in-front group compared to the V-around and V-pref groups. However, the subjective assessment of the helpfulness of the circle was higher in the V-in-front group. In addition, the low consistency of the V-in-front group was alleviated in the participants in the V-pref group who chose to place the circle in front of the hole. In contrast, the subjective assessment of the helpfulness of the circle was low in the V-in-front group. These findings suggest that while providing autonomy – that is, when the participant is able to choose for him/herself – can improve motor learning, there may be a dissociation between an individual’s subjective assessment and the actual helpfulness of a visual aid. This dissociation may be termed preference-performance dissociation, and coaches and instructors who teach closed, self-paced motor skills should be aware of the fact that when providing learners with the autonomy to choose a practice aid in order to improve their skills, some may not choose the aid that is effective for them.

Episodic memory improvements due to noninvasive stimulation targeting the cortical-hippocampal network: A replication and extension experiment.

IntroductionThe distributed cortical network of the human hippocampus is important for episodic memory. In a previous experiment, noninvasive stimulation of the hippocampal‐cortical network applied for five consecutive days improved paired‐associate learning measured after the stimulation regimen via cued recall (Wang et al., Science, 2014, 345, 1054). This finding has not yet been directly replicated. Furthermore, evidence for long‐lasting effects of stimulation on paired‐associate learning was obtained by analyzing relatively small subsamples (Wang & Voss, Hippocampus, 2015, 25, 877) and requires further evaluation.MethodsSixteen healthy young adults participated in this replication study using the same experimental design as the original study. Participants received 1 week of active stimulation and 1 week of sham stimulation, with memory assessments occurring at the beginning (pre) and end (post) of each week. Assessments included the paired‐associate task used in the original study, as well as a long‐term episodic memory retention task in order to test the hypothesis that increased paired‐associate learning could come at the cost of accelerated long‐term forgetting. Change in memory scores was evaluated within (pre vs. post) and across (active vs. sham) weeks.ResultsSimilar to Wang et al., paired‐associate learning was significantly improved after 1 week of active stimulation but not after 1 week of sham stimulation. We found no evidence that stimulation increased long‐term forgetting for either week.ConclusionThese findings confirm the beneficial effects of stimulation on episodic memory that were reported previously and indicate that stimulation‐related gains in new learning ability do not come at the price of accelerated long‐term forgetting.

Chronic Cognitive Deficits and Associated Histopathology Following Closed-Head Concussive Injury in Rats.

Close-head concussive injury, as one of the most common forms of traumatic brain injury (TBI), has been shown to induce cognitive deficits that are long lasting. A concussive impact model was previously established in our lab that produces clinically relevant signs of concussion and induced acute pathological changes in rats. To evaluate the long-term effects of repeated concussions in this model, we utilized a comprehensive Morris water maze (MWM) paradigm for cognitive assessments at 1 and 6 months following repeated concussive impacts in rats. As such, adult Sprague-Dawley rats received either anesthesia (sham) or repeated concussive impacts (4 consecutive impacts at 1 h interval). At 1 month post-injury, results of the spatial learning task showed that the average latencies to locate the hidden “escape” platform were significantly longer in the injured rats over the last 2 days of the MWM testing compared to sham controls (p < 0.05). In the memory retention task, rats subjected to repeated concussive impacts also spent significantly less time in the platform zone searching for the missing platform during the probe trial (p < 0.05). On the working memory task, the injured rats showed a trend toward worse performance, but this failed to reach statistical significance compared to sham controls (p = 0.07). At 6 months post-injury, no differences were detected between the injured group and sham controls in either the spatial learning or probe trials. However, rats with repeated concussive impacts exhibited significantly worsened working memory performance compared to sham controls (p < 0.05). In addition, histopathological assessments for axonal neurodegeneration using silver stain showed that repeated concussive impacts induced significantly more axonal degeneration in the corpus callosum compared to sham controls (p < 0.05) at 1 month post-injury, whereas such difference was not observed at 6 months post-injury. Overall, the results show that repeated concussive impacts in our model produced significant cognitive deficits in both spatial learning abilities and in working memory abilities in a time-dependent fashion that may be indicative of progressive pathology and warrant further investigation.

Time-dependent motor memory representations in prefrontal cortex

How memories evolve over time is fundamental for understanding memory. Hippocampus-dependent episodic memories are generally assumed to undergo a time-dependent neural reorganization involving an increased reliance on neocortical areas. Yet, whether other forms of memory undergo a similar reorganization over time remains unclear. Here, we examined whether the neural underpinnings of motor sequence memories change over time. Participants were trained on a motor sequence learning task. Either 1d or 28d later, they performed a retention test for this task in the fMRI scanner. Sequence-specific motor memory was observed both 1d and 28d after initial training. Bayesian second-level fMRI analyses suggested a higher probability for task activity in the middle frontal gyrus and frontal pole 28d compared to 1d after initial motor learning. Searchlight representational similarity analysis indicated that areas in middle and superior frontal cortex were more involved in differentiating between multivariate activity patterns for old motor sequence memories and newly learned motor sequences in the 28d-group compared to the 1d-group. This increased involvement of lateral frontal areas during the task after 28 days was not paralleled by a decrease in those areas that were involved in performing the motor sequence retention task after 1d. These novel findings provide insights into how memories beyond the hippocampus evolve over time.