Episodic memory assessment: effects of sex and age on performance and response time during a continuous recognition task.

Introduction: Continuous recognition tasks (CRTs) assess episodic memory (EM), the central functional disturbance in Alzheimer's disease and several related disorders. The online MemTrax computerized CRT provides a platform for screening and assessment that is engaging and can be repeated frequently. MemTrax presents complex visual stimuli, which require complex involvement of the lateral and medial temporal lobes and can be completed in less than 2 min. Results include number of correct recognitions (HITs), recognition failures (MISSes = 1-HITs), correct rejections (CRs), false alarms (FAs = 1-CRs), total correct (TC = HITs + CRs), and response times (RTs) for each HIT and FA. Prior analyses of MemTrax CRT data show no effects of sex but an effect of age on performance. The number of HITs corresponds to faster RT-HITs more closely than TC, and CRs do not relate to RT-HITs. RT-HITs show a typical skewed distribution, and cumulative RT-HITs fit a negative survival curve (RevEx). Thus, this study aimed to define precisely the effects of sex and age on HITS, CRs, RT-HITs, and the dynamics of RTs in an engaged population. Methods: MemTrax CRT online data on 18,255 individuals was analyzed for sex, age, and distributions of HITs, CRs, MISSes, FAs, TC, and relationships to both RT-HITs and RT-FAs. Results: HITs corresponded more closely to RT-HITs than did TC because CRs did not relate to RT-HITs. RT-FAs had a broader distribution than RT-HITs and were faster than RT-HITs in about half of the sample, slower in the other half. Performance metrics for men and women were the same. HITs declined with age as RT-HITs increased. CRs also decreased with age and RT-FAs increased, but with no correlation. The group over aged 50 years had RT-HITs distributions slower than under 50 years. For both age ranges, the RevEx model explained more than 99% of the variance in RT-HITs. Discussion: The dichotomy of HITs and CRs suggests opposing cognitive strategies: (1) less certainty about recognitions, in association with slower RT-HITs and lower HIT percentages suggests recognition difficulty, leading to more MISSes, and (2) decreased CRs (more FAs) but faster RTs to HITs and FAs, suggesting overly quick decisions leading to errors. MemTrax CRT performance provides an indication of EM (HITs and RT-HITs may relate to function of the temporal lobe), executive function (FAs may relate to function of the frontal lobe), processing speed (RTs), cognitive ability, and age-related changes. This CRT provides potential clinical screening utility for early Alzheimer's disease and other conditions affecting EM, other cognitive functions, and more accurate impairment assessment to track changes over time.

An advanced course sequence in eukaryotic cell and molecular biology: A year-long course where active learning and peer-led groups resulted in higher learning gains and significant course passing scores.

We developed an advanced, year-long course sequence in eukaryotic cell and molecular biology in order to increase conceptual understanding. Three years of historical data from a one semester, traditional-lecture, senior cell and molecular biology course (n = 237) were compared with 3 years of data collected from the year-long course sequence (n = 176). There were significant content gains for the students who enrolled in the course sequence when pre- and post-assessments were compared (p < 0.0001). There was an association between earning a C or better in the course sequence and 70% or higher in the post-assessment instrument (p < 0.05). Final course grades for Bio 135A were calculated from three open ended exams and the percentage of correct answers on the clicker questions. For Bio135B, final grades were calculated from three open ended exams, clicker responses, a seven-page literature review on an environmental carcinogen and its effects on signal transduction pathways, and a formal presentation of one of the research articles they used in the literature review. The students who took the second semester of the course passed at higher rates than the students who enrolled in the traditional-lecture course (p < 0.05). Clicker answers to the research problem sets and the final course grades correlated significantly for both semesters of the course sequence (p < 0.01). We conclude that conceptually-connected learning gains can be obtained when the content is taught in a format that includes short lectures and group work to solve research questions.

Postpartum Mental Health and Perceptions of Discrimination Among Asian Fathers During the COVID-19 Pandemic.

PURPOSE: The purpose of this study was twofold: (1) to examine the prevalence of postpartum depression and anxiety symptomatology among fathers of Asian descent living in North America during the COVID-19 pandemic, and (2) to identify the occurrences of online racial discrimination. STUDY DESIGN AND METHODS: Using a cross-sectional design and convenience sampling methods, we recruited fathers online via social media sites (Facebook, Instagram) between March 12 and July 31, 2022. The Edinburgh Postnatal Depression Scale, General Anxiety Scale, and the Online Victimization Scale assessed mental health well-being and discrimination outcomes. Data were analyzed using descriptive statistics, two sample t-test, chi-square test of independence, and Pearson's correlation analysis. RESULTS: Our sample included 61 fathers within 6 months postpartum living in the United States and Canada. Participants were on average 34 years old, married, and represented 17 Asian ethnic groups, including Asian Indian (41%), Filipino (11.3%), and Korean (8.1%). One-third of our participants (31.1%, n = 19) were at high risk of developing postpartum depression and scores of three (4.9%) fathers indicated they had clinically significant anxiety. Overall, 26.3% reported experiencing direct online racial discrimination and 65% reported occurrences of indirect online racial discrimination. CLINICAL IMPLICATIONS: There was a high rate of depressive symptoms and occurrences of online racial discrimination among fathers of Asian descent living in North America. These rates are higher than the general perinatal population and further research is warranted to examine risk factors and preventive strategies among this unique paternal ethnic group.

Correctness and response time distributions in the MemTrax continuous recognition task: Analysis of strategies and a reverse-exponential model.

A critical issue in addressing medical conditions is measurement. Memory measurement is difficult, especially episodic memory, which is disrupted by many conditions. On-line computer testing can precisely measure and assess several memory functions. This study analyzed memory performances from a large group of anonymous, on-line participants using a continuous recognition task (CRT) implemented at https://memtrax.com. These analyses estimated ranges of acceptable performance and average response time (RT). For 344,165 presumed unique individuals completing the CRT a total of 602,272 times, data were stored on a server, including each correct response (HIT), Correct Rejection, and RT to the thousandth of a second. Responses were analyzed, distributions and relationships of these parameters were ascertained, and mean RTs were determined for each participant across the population. From 322,996 valid first tests, analysis of correctness showed that 63% of these tests achieved at least 45 correct (90%), 92% scored at or above 40 correct (80%), and 3% scored 35 correct (70%) or less. The distribution of RTs was skewed with 1% faster than 0.62 s, a median at 0.890 s, and 1% slower than 1.57 s. The RT distribution was best explained by a novel model, the reverse-exponential (RevEx) function. Increased RT speed was most closely associated with increased HIT accuracy. The MemTrax on-line memory test readily provides valid and reliable metrics for assessing individual episodic memory function that could have practical clinical utility for precise assessment of memory dysfunction in many conditions, including improvement or deterioration over time.

Artificial gravity partially protects space-induced neurological deficits in Drosophila melanogaster.

Spaceflight poses risks to the central nervous system (CNS), and understanding neurological responses is important for future missions. We report CNS changes in Drosophila aboard the International Space Station in response to spaceflight microgravity (SFµg) and artificially simulated Earth gravity (SF1g) via inflight centrifugation as a countermeasure. While inflight behavioral analyses of SFµg exhibit increased activity, postflight analysis displays significant climbing defects, highlighting the sensitivity of behavior to altered gravity. Multi-omics analysis shows alterations in metabolic, oxidative stress and synaptic transmission pathways in both SFµg and SF1g; however, neurological changes immediately postflight, including neuronal loss, glial cell count alterations, oxidative damage, and apoptosis, are seen only in SFµg. Additionally, progressive neuronal loss and a glial phenotype in SF1g and SFµg brains, with pronounced phenotypes in SFµg, are seen upon acclimation to Earth conditions. Overall, our results indicate that artificial gravity partially protects the CNS from the adverse effects of spaceflight.

Immunological and hematological outcomes following protracted low dose/low dose rate ionizing radiation and simulated microgravity.

Using a ground-based model to simulate spaceflight [21-days of single-housed, hindlimb unloading (HLU) combined with continuous low-dose gamma irradiation (LDR, total dose of 0.04 Gy)], an in-depth survey of the immune and hematological systems of mice at 7-days post-exposure was performed. Collected blood was profiled with a hematology analyzer and spleens were analyzed by whole transcriptome shotgun sequencing (RNA-sequencing). The results revealed negligible differences in immune differentials. However, hematological system analyses of whole blood indicated large disparities in red blood cell differentials and morphology, suggestive of anemia. Murine Reactome networks indicated majority of spleen cells displayed differentially expressed genes (DEG) involved in signal transduction, metabolism, cell cycle, chromatin organization, and DNA repair. Although immune differentials were not changed, DEG analysis of the spleen revealed expression profiles associated with inflammation and dysregulated immune function persist to 1-week post-simulated spaceflight. Additionally, specific regulation pathways associated with human blood disease gene orthologs, such as blood pressure regulation, transforming growth factor-ß receptor signaling, and B cell differentiation were noted. Collectively, this study revealed differential immune and hematological outcomes 1-week post-simulated spaceflight conditions, suggesting recovery from spaceflight is an unremitting process.

Beyond Low-Earth Orbit: Characterizing Immune and microRNA Differentials following Simulated Deep Spaceflight Conditions in Mice.

Spaceflight missions can cause immune system dysfunction in astronauts with little understanding of immune outcomes in deep space. This study assessed immune responses in mice following ground-based, simulated deep spaceflight conditions, compared with data from astronauts on International Space Station missions. For ground studies, we simulated microgravity using the hindlimb unloaded mouse model alone or in combination with acute simulated galactic cosmic rays or solar particle events irradiation. Immune profiling results revealed unique immune diversity following each experimental condition, suggesting each stressor results in distinct circulating immune responses, with clear consequences for deep spaceflight. Circulating plasma microRNA sequence analysis revealed involvement in immune system dysregulation. Furthermore, a large astronaut cohort showed elevated inflammation during low-Earth orbit missions, thereby supporting our simulated ground experiments in mice. Herein, circulating immune biomarkers are defined by distinct deep space irradiation types coupled to simulated microgravity and could be targets for future space health initiatives.

Neutrophil-to-Lymphocyte Ratio: A Biomarker to Monitor the Immune Status of Astronauts.

A comprehensive understanding of spaceflight factors involved in immune dysfunction and the evaluation of biomarkers to assess in-flight astronaut health are essential goals for NASA. An elevated neutrophil-to-lymphocyte ratio (NLR) is a potential biomarker candidate, as leukocyte differentials are altered during spaceflight. In the reduced gravity environment of space, rodents and astronauts displayed elevated NLR and granulocyte-to-lymphocyte ratios (GLR), respectively. To simulate microgravity using two well-established ground-based models, we cultured human whole blood-leukocytes in high-aspect rotating wall vessels (HARV-RWV) and used hindlimb unloaded (HU) mice. Both HARV-RWV simulation of leukocytes and HU-exposed mice showed elevated NLR profiles comparable to spaceflight exposed samples. To assess mechanisms involved, we found the simulated microgravity HARV-RWV model resulted in an imbalance of redox processes and activation of myeloperoxidase-producing inflammatory neutrophils, while antioxidant treatment reversed these effects. In the simulated microgravity HU model, mitochondrial catalase-transgenic mice that have reduced oxidative stress responses showed reduced neutrophil counts, NLR, and a dampened release of selective inflammatory cytokines compared to wildtype HU mice, suggesting simulated microgravity induced oxidative stress responses that triggered inflammation. In brief, both spaceflight and simulated microgravity models caused elevated NLR, indicating this as a potential biomarker for future in-flight immune health monitoring.

Can Clinical Simulation Increase Confidence Levels in Performing Postpartum Care in a Diverse Group of Baccalaureate Nursing Students?

Nursing duties are often sensitive in nature and may contribute to feelings of inadequacy for students, especially when providing postpartum care. Our study assessed confidence levels among 61 junior baccalaureate nursing students before and after a simulation workshop with a follow-up survey administered after completion of two full clinical days on a postpartum unit. The four-hour simulation included stations for breast, fundus, and lochia exam skills. Overall confidence and confidence in performing patient assessments were significantly increased at postsimulation and follow-up (p < .001), demonstrating the efficacy of the simulation.

Detection of Borrelia burgdorferi, Ehrlichia chaffeensis, and Anaplasma phagocytophilum in ticks (Acari: Ixodidae) from a coastal region of California.

A study was conducted in Santa Cruz County to estimate the prevalence and distribution of the agents of Lyme disease, human granulocytic (HGE), and human monocytic (HME) ehrlichiosis in 1,187 adult ixodid ticks collected from eight public-use recreation areas over a 2-yr period. Borrelia burgdorferi, the causative agent of Lyme disease, was detected by a polymerase chain reaction (PCR) in 44 of 776 (5.67%) Ixodes pacificus ticks and in 3 of 58 (5.17%) Dermacentor variabilis ticks. Anaplasma phagocytophilum, the causative agent of HGE, was detected by PCR in 48 (6.19%) I. pacificus ticks and 5 (8.62%) D. variabilis ticks. Ehrlichia chaffeensis, the causative agent of HME, was detected by nested PCR in just five (0.64%) I. pacificus ticks and four (6.9%) D. variabilis ticks. Interestingly, eight (1.03%) I. pacificus ticks were co-infected with B. burgdorferi and A. phagocytophilum, and just one (0.12%) tick was co-infected with B. burgdorferi and E. chaffeensis. Less than 1% of 353 Dermacentor occidentalis ticks showed evidence of infection with any of the agents tested. To our knowledge, this is the first reported identification of A. phagocytophilum and E. chaffeensis in D. occidentalis ticks from California This study represents the first extensive survey of Lyme and the ehrlichial diseases across multiple areas of Santa Cruz County, and suggests that prevalence of B. burgdorferi in Santa Cruz County may be higher than other areas of the state.

Transcranial magnetic stimulation: neurophysiological applications and safety.

TMS is a non-invasive tool for measuring neural conduction and processing time, activation thresholds, facilitation and inhibition in brain cortex, and neural connections in humans. It is used to study motor, visual, somatosensory, and cognitive functions. TMS does not appear to cause long-term adverse neurological, cardiovascular, hormonal, motor, sensory, or cognitive effects in healthy subjects. Single-pulse (<1Hz) TMS is safe in normal subjects. High frequency, high-intensity repetitive TMS (rTMS) can elicit seizures even in normal subjects. Safety guidelines for using rTMS have been published.

An unbiased measure of the contributions of chroma and luminance to saccadic suppression of displacement.

Perception of image displacement is suppressed during saccadic eye movements. We probed the source of saccadic suppression of displacement by testing whether it selectively affects chromatic- or luminance-based motion information. Human subjects viewed a stimulus in which chromatic and luminance cues provided conflicting information about displacement direction. Apparent motion occurred during either fixation or a 19.5 degree saccade. Subjects detected motion and discriminated displacement direction in each trial. They reported motion in over 90% of fixation trials and over 70% of saccade trials. During fixation, the probability of perceiving the direction carried by chromatic cues decreased as luminance contrast increased. During saccades, subjects tended to perceive the direction indicated by luminance cues when luminance contrast was high. However, when luminance contrast was low, subjects showed no preference for the chromatic- or luminance-based direction. Thus magnocellular channels are suppressed, while stimulation of parvocellular channels is below threshold, so that neither channel drives motion perception during saccades. These results confirm that magnocellular inhibition is the source of saccadic suppression.