Search

BackgroundAlthough Black/African American older adults bear significant inequities in prevalence, incidence, and outcomes of Alzheimer's disease and related dementias, they are profoundly under-included in Alzheimer's Disease research. Community-Engaged Research (e.g., equitable community/science partnerships) is an evidence-based approach for improving engagement of underrepresented populations into Alzheimer's Disease research, but has lacked scalability to the national level. As internet use among older adults from underrepresented populations continues to grow, internet-based research shows promise as a feasible, valid approach to engagement and longitudinal assessment. The Community Engaged Digital Alzheimer's Research (CEDAR) study utilizes a community-engaged research approach to increase the engagement and research participation of Black/African American adults in the Brain Health Registry (BHR) and Alzheimer Disease clinical research.ObjectivesTo describe the methods and evaluate the feasibility of the CEDAR culturally-informed digital platform within BHR.DesignAll Black/African American participants in BHR were invited to enroll in CEDAR and to consider serving on a newly convened Community-Scientific Partnership Board to guide the study. The community board guided the development a culturally-informed cadre of engagement materials and strategies to increase research participation. Engagement strategies included incentives for study task completion, culturally-informed communications (e.g., landing page, emails and social media), resources about brain health, and video and written testimonials by CEDAR participants.SettingBHR, an Internet-based registry and cohort.ParticipantsBHR participants self-identifying as Black/African American were invited to enroll. All participants who signed an online informed consent document were enrolled.MeasurementsWe report the number of participants invited, enrolled, completed tasks, and volunteered to join the community board. We compared the demographics, cognitive profile, and baseline BHR task completion rates between CEDAR participants and all those invited to join the study.ResultsOf 3738 invited, 349 (9.34%) enrolled in CEDAR. 134 (37% of CEDAR participants) volunteered to join the community board, of which 19 were selected for the community board. Compared to those invited, the CEDAR cohort had a higher percentage of female participants (84.5%) and a lower percentage of participants who identify as belonging to more than one ethnocultural group (21.8%). Compared to those did not enroll in CEDAR, those enrolled in CEDAR had a higher percentage of participants completing all BHR tasks (22%) and a higher percentage of participants completing at least one cognitive test (76%). Those enrolled in CEDAR also had a higher percentage of participants having an enrolled study partner (18%).ConclusionsA culturally-informed Community-Engaged Research approach, including a remotely-convened community board, to engagement of Black/African American participants in an online research registry is feasible. This approach can be adapted for use in various clinical studies and other settings. Future studies will evaluate the effectiveness of the engagement strategies.

BackgroundFailure of Alzheimer's disease and related diseases (ADRD) research studies to include and engage Black participants is a major issue, which limits the impact and generalizability of research findings. Little is known about participation of Black adults in online ADRD-related research registries.ObjectivesAs part of the Community Engaged Digital Alzheimer's Research (CEDAR) Study, this study aims to increase our understanding of facilitators and barriers of Black adults to participating in ADRD-related online registries, as well as to understand their preferences for communication channels.Design, setting, participants, measurementsWe invited all Black participants enrolled in the Brain Health Registry (BHR) to complete a cross-sectional online survey. The survey consisted of rating scales and open-text questions asking about their attitudes towards brain health research, reasons for joining and continuing to participate in BHR, difficulties with participating, and preferences for modes of contact and website usage.ResultsOf all invited Black BHR participants (N=3,636), 198 (5.5%) completed the survey. The mean age was 58.4 (SD=11.3), mean years of education were 16.3 (SD=2.4), and 85.5% identified as female. Reported facilitators for joining and continuing to participate in BHR were personal interest (e.g., learning more about own brain health) and altruism (e.g., helping research). Among additional registry features which could encourage return, receiving feedback or scores about BHR tasks was rated the highest. Of those who found BHR participation difficult (21%), the most frequent reason was time burden. The most preferred way of receiving study information was via email. Participants reported that the websites that they used the most were YouTube and Facebook.DiscussionThe results of our study can inform the development of culturally-responsive registry features and engagement efforts to improve inclusion and participation of Black adults in online ADRD research. Providing participants with feedback about their registry performance and reducing the number of registry tasks are among the recommended strategies.

Objective: To systematically evaluate definitions of "racial health equity" and related terms within health-related academic literature., Study Design and Setting: We systematically evaluated definitions of racial health equity and related terms within health-related academic articles. Articles published in English were included, and no date restrictions were imposed., Results: We found 20 original articles containing relevant definitions out of 1816 retrieved articles, thirteen of which were published from 2020-2023. Themes used in the definitions varied, with racism (n= 12) and quality of healthcare (n= 10) being the most common. Additional themes, including social hierarchy or marginalization, discrimination, justice, unmet social needs, and historical events were used by some definitions. Eleven of the included manuscripts defined race as a social construct., Conclusion: This study depicts racial health equity as an emerging concept with limited consensus on racism, quality of health, and social determinants of health as important underlying frameworks. To center equity efforts and actions under a workable and shared vision, we recommend continued discussions regarding underlying meanings of racial health equity concepts and propose establishing a definition that promotes unity across health fields and prevents ambiguity., (Copyright © 2024. Published by Elsevier Inc.)

Objective: Considering that diagnostic decisions about mTBI are often predicated on clinical symptom criteria, it is imperative to determine which initial presentation features of mTBI have prognostic significance for identifying those at high risk for long-term functional impairment., Setting: Zoom interview Participants: Male, former NCAA Division I, and professional-level National Football League (NFL) athletes ( n  = 177) between the ages of 27 and 85 ( M  = 54.1, SD = 14.7)., Design: Cross-sectional case-control. Main Measures: History of mild TBI, history of loss of consciousness (LOC), depression symptoms, insomnia, neurobehavioral symptoms., Results: Number of mTBI exposures did not predict neurobehavioral symptoms (B = 0.21, SE = 0.18, p  = 0.23), but number of mTBI + LOC events did (B = 2.27, SE = 0.64, p  = <.001). Further analysis revealed that the number of mTBI + LOC events predicted neurobehavioral symptoms indirectly through both depression (B = 0.85, 95% CI = [0.27, 1.52) and insomnia (B = 0.81, 95% CI = [0.3, 1.4]). Further, the direct effect of mTBI + LOC events on neurobehavioral symptoms became non-significant when depression and insomnia were added to the model (B = 0.78, SE = 0.45, p  = 0.08)., Conclusions: Findings support LOC at time of injury as an important predictor of long-term outcomes. Additionally, results suggest depression and insomnia as potential mediators in the association between mTBI + LOC and neurobehavioral symptoms. These findings provide justification for early depression and insomnia symptom monitoring following mTBI + LOC.

Fragile X syndrome (FXS) arises from the loss of fragile X messenger ribonucleoprotein (FMRP) needed for normal neuronal excitability and circuit functions. Recent work revealed that FMRP contributes to mossy fiber long-term potentiation by adjusting the Kv4 A-type current availability through interactions with a Cav3-Kv4 ion channel complex, yet the mechanism has not yet been defined. In this study using wild-type and Fmr1 knock-out (KO) tsA-201 cells and cerebellar sections from male Fmr1 KO mice, we show that FMRP associates with all subunits of the Cav3.1-Kv4.3-KChIP3 complex and is critical to enabling calcium-dependent shifts in Kv4.3 inactivation to modulate the A-type current. Specifically, upon depolarization Cav3 calcium influx activates dual-specific phosphatase 1/6 (DUSP1/6) to deactivate ERK1/2 (ERK) and lower phosphorylation of Kv4.3, a signaling pathway that does not function in Fmr1 KO cells. In Fmr1 KO mouse tissue slices, cerebellar granule cells exhibit a hyperexcitable response to membrane depolarizations. Either incubating Fmr1 KO cells or in vivo administration of a tat-conjugated FMRP N-terminus fragment (FMRP-N-tat) rescued Cav3-Kv4 function and granule cell excitability, with a decrease in the level of DUSP6. Together these data reveal a Cav3-activated DUSP signaling pathway critical to the function of a FMRP-Cav3-Kv4 complex that is misregulated in Fmr1 KO conditions. Moreover, FMRP-N-tat restores function of this complex to rescue calcium-dependent control of neuronal excitability as a potential therapeutic approach to alleviating the symptoms of FXS., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 the authors.)

Background and Objectives: Obstructive sleep apnea (SA) is common in older men and a contributor to negative cognitive, psychiatric, and brain health outcomes. Little is known about SA in those who played contact sports and are at increased risk of neurodegenerative disease(s) and other neuropathologies associated with repetitive head impacts (RHI). In this study, we investigated the frequency of diagnosed and witnessed SA and its contribution to clinical symptoms and tau pathology using PET imaging among male former college and former professional American football players., Methods: The sample included 120 former National Football League (NFL) players, 60 former college players, and 60 asymptomatic men without exposure to RHI (i.e., controls). Diagnosed SA was self-reported, and all participants completed the Mayo Sleep Questionnaire (MSQ, informant version), the Epworth Sleepiness Scale (ESS), neuropsychological testing, and tau (flortaucipir) PET imaging. Associations between sleep indices (diagnosed SA, MSQ items, and the ESS) and derived neuropsychological factor scores, self-reported depression (Beck Depression Inventory-II [BDI-II]), informant-reported neurobehavioral dysregulation (Behavior Rating Inventory of Executive Function-Adult Version [BRIEF-A] Behavioral Regulation Index [BRI]), and tau PET uptake, were tested., Results: Approximately 36.7% of NFL players had diagnosed SA compared with 30% of the former college football players and 16.7% of the controls. Former NFL players and college football players also had higher ESS scores compared with the controls. Years of football play was not associated with any of the sleep metrics. Among the former NFL players, diagnosed SA was associated with worse Executive Function and Psychomotor Speed factor scores, greater BDI-II scores, and higher flortaucipir PET standard uptake value ratios, independent of age, race, body mass index, and APOE ε4 gene carrier status. Higher ESS scores correlated with higher BDI-II and BRIEF-A BRI scores. Continuous positive airway pressure use mitigated all of the abovementioned associations. Among the former college football players, witnessed apnea and higher ESS scores were associated with higher BRIEF-A BRI and BDI-II scores, respectively. No other associations were observed in this subgroup., Discussion: Former elite American football players are at risk of SA. Our findings suggest that SA might contribute to cognitive, neuropsychiatric, and tau outcomes in this population. Like all neurodegenerative diseases, this study emphasizes the multifactorial contributions to negative brain health outcomes and the importance of sleep for optimal brain health., Competing Interests: The authors report no relevant disclosures. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp., (© 2024 American Academy of Neurology.)

Sociocontextual factors powerfully shape risk for age-related cognitive impairment, including excess risk burdening medically underserved populations. Lifecourse adversity associates with cognitive aging, but harms are likely mitigable. Understanding population-salient relationships and sensitive periods for exposure is crucial for targeting clinical interventions., Objective: The authors examined childhood and adulthood traumatic events in relation to cognition among Black and White older adults in the Health and Retirement Study (HRS)., Participants: Participants (N = 13,952) aged 55+ had complete lifetime trauma and cognitive testing data at the 2006/08, 2010/12, and/or 2014/16 waves., Measures: Trauma indices comprised childhood and adulthood event counts. Outcomes included baseline performance and trajectories on the Telephone Interview for Cognitive Status., Design: Main and nonlinear trauma effects were modeled via linear regression, and overall contributions assessed with omnibus likelihood ratio tests., Results: Black participants (N = 2,345) reported marginally lower adulthood trauma exposure than White participants (N = 11,607) with no other exposure differentials observed. In White participants only, greater childhood trauma exposure predicted worse baseline cognition but slower change over time. Across race, adulthood trauma robustly associated with baseline cognition. Relationships were frequently nonlinear: low but nonzero trauma predicted highest cognitive scores, with much poorer cognition observed as trauma exposure increased. Relationships between adulthood trauma and trajectory were limited to the White sample., Conclusion: Traumatic experiences, particularly in adulthood, may impact late-life cognitive health if not addressed. Findings highlight foci for clinical researchers and providers: adverse life events as a source of cognitive risk, and identification of community-specific resources that buffer behavioral, physical, and mental health sequelae of previous and incident trauma., Competing Interests: DISCLOSURES The authors have no conflicts of interest to declare. This work was supported by theAlzheimer's Associationunder awardsAARF-18-562958(Zuelsdorff) andAARFD-21-852952(Byrd) and by theNational Institute on Aging,K01AG068376(Byrd). The content is solely the responsibility of the authors and does not necessarily represent the official views of the Alzheimer's Association., (Copyright © 2023 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.)

Introduction: Tau is a key pathology in chronic traumatic encephalopathy (CTE). Here, we report our findings in tau positron emission tomography (PET) measurements from the DIAGNOSE CTE Research Project., Method: We compare flortaucipir PET measures from 104 former professional players (PRO), 58 former college football players (COL), and 56 same-age men without exposure to repetitive head impacts (RHI) or traumatic brain injury (unexposed [UE]); characterize their associations with RHI exposure; and compare players who did or did not meet diagnostic criteria for traumatic encephalopathy syndrome (TES)., Results: Significantly elevated flortaucipir uptake was observed in former football players (PRO+COL) in prespecified regions (p < 0.05). Association between regional flortaucipir uptake and estimated cumulative head impact exposure was only observed in the superior frontal region in former players over 60 years old. Flortaucipir PET was not able to differentiate TES groups., Discussion: Additional studies are needed to further understand tau pathology in CTE and other individuals with a history of RHI., (© 2023 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: In Alzheimer's disease (AD) research, subjective reports of cognitive and functional decline from participant-study partner dyads is an efficient method of assessing cognitive impairment and clinical progression., Methods: Demographics and subjective cognitive/functional decline (Everyday Cognition Scale [ECog]) scores from dyads enrolled in the Brain Health Registry (BHR) Study Partner Portal were analyzed. Associations between dyad characteristics and both ECog scores and study engagement were investigated., Results: A total of 10,494 BHR participants (mean age = 66.9 ± 12.16 standard deviations, 67.4% female) have enrolled study partners (mean age = 64.3 ± 14.3 standard deviations, 49.3% female), including 8987 dyads with a participant 55 years of age or older. Older and more educated study partners were more likely to complete tasks and return for follow-up. Twenty-five percent to 27% of older adult participants had self and study partner-report ECog scores indicating a possible cognitive impairment., Discussion: The BHR Study Partner Portal is a unique digital tool for capturing dyadic data, with high impact applications in the clinical neuroscience and AD fields. Highlights The Brain Health Registry (BHR) Study Partner Portal is a novel, digital platform of >10,000 dyads. Collection of dyadic online subjective cognitive and functional data is feasible. The portal has good usability as evidenced by positive study partner feedback. The portal is a potential scalable strategy for cognitive impairment screening in older adults., (© 2023 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: In the USA, access to quality healthcare varies greatly across racial and ethnic groups, resulting in significant health disparities. A new term, "racial health equity" (RHE), is increasingly reported in the medical literature, but there is currently no consensus definition of the term. Additionally, related terms such as "health disparities," "health inequities," and "equality" have been inconsistently used when defining RHE., Methods: The primary purpose of this scoping review is to investigate the current use and underlying concepts used to define racial health equity. The study will address two key questions: (1) "What terminology and definitions have been used to characterize RHE?" and (2) "What knowledge gaps and challenges are present in the current state of RHE research and theory?" The review will collect and analyze data from three sources: (1) websites from key national and international health organizations, (2) theoretical and narrative published articles, and (3) evidence synthesis studies addressing interventions targeting racial health equity and minority stakeholder engagement., Discussion: Defining "racial health equity" and related terminology is the first step to advancing racial health equity within the USA. This review aims to offer an improved understanding of RHE constructs and definitions, bringing greater unity to national racial health equity research efforts across disciplines., Systematic Review Registration: This protocol is registered with the Open Science Framework at https://osf.io/7pvzq ., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Multiple methods for quantitative proteomics are available for proteome profiling. It is unclear which methods are most useful in situations involving deep proteome profiling and the detection of subtle distortions in the proteome. Here, we compared the performance of seven different strategies in the analysis of a mouse model of Fragile X Syndrome, involving the knockout of the fmr1 gene that is the leading cause of autism spectrum disorder. Focusing on the cerebellum, we show that data-independent acquisition (DIA) and the tandem mass tag (TMT)-based real-time search method (RTS) generated the most informative profiles, generating 334 and 329 significantly altered proteins, respectively, although the latter still suffered from ratio compression. Label-free methods such as BoxCar and a conventional data-dependent acquisition were too noisy to generate a reliable profile, while TMT methods that do not invoke RTS showed a suppressed dynamic range. The TMT method using the TMTpro reagents together with complementary ion quantification (ProC) overcomes ratio compression, but current limitations in ion detection reduce sensitivity. Overall, both DIA and RTS uncovered known regulators of the syndrome and detected alterations in calcium signaling pathways that are consistent with calcium deregulation recently observed in imaging studies. Data are available via ProteomeXchange with the identifier PXD039885.

Introduction: The projected growth of Alzheimer's disease (AD) and AD-related dementia (ADRD) cases by midcentury has expanded the research field and impelled new lines of inquiry into structural and social determinants of health (S/SDOH) as fundamental drivers of disparities in AD/ADRD., Methods: In this review, we employ Bronfenbrenner's ecological systems theory as a framework to posit how S/SDOH impact AD/ADRD risk and outcomes., Results: Bronfenbrenner defined the "macrosystem" as the realm of power (structural) systems that drive S/SDOH and that are the root cause of health disparities. These root causes have been discussed little to date in relation to AD/ADRD, and thus, macrosystem influences, such as racism, classism, sexism, and homophobia, are the emphasis in this paper., Discussion: Under Bronfenbrenner's macrosystem framework, we highlight key quantitative and qualitative studies linking S/SDOH with AD/ADRD, identify scientific gaps in the literature, and propose guidance for future research., Highlights: Ecological systems theory links structural/social determinants to AD/ADRD. Structural/social determinants accrue and interact over the life course to impact AD/ADRD. Macrosystem is made up of societal norms, beliefs, values, and practices (e.g., laws). Most macro-level determinants have been understudied in the AD/ADRD literature., (© 2023 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: Extracellular signal-regulated kinase (ERK/MAPK) pathway in the brain is hypothesized to be a critical convergent node in the development of autism spectrum disorder. We reasoned that selectively targeting this pathway could reverse core autism-like phenotype in animal models., Methods: Here we tested a clinically relevant, selective inhibitor of ERK pathway, PD325901 (Mirdametinib), in a mouse model of idiopathic autism, the BTBR mice., Findings: We report that treating juvenile mice with PD325901 reduced ERK pathway activation, dose and duration-dependently reduced core disease-modeling deficits in sociability, vocalization and repetitive behavior, and reversed abnormal EEG signals. Further analysis revealed that subchronic treatment did not affect weight gain, locomotion, or neuronal density in the brain. Parallel treatment in the C57BL/6J mice did not alter their phenotype., Interpretation: Our data indicate that selectively inhibiting ERK pathway using PD325901 is beneficial in the BTBR model, thus further support the notion that ERK pathway is critically involved in the pathophysiology of autism. These results suggest that a similar approach could be applied to animal models of syndromic autism with dysregulated ERK signaling, to further test selectively targeting ERK pathway as a new approach for treating autism., Funding: This has beenwork was supported by Alberta Children's Hospital Research Foundation (JMR & NC), University of Calgary Faculty of Veterinary Medicine (NC), Kids Brain Health Network (NC), and Natural Sciences and Engineering Research Council of Canada (NC)., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

This study explores the relationship between religious service attendance, social ties, and health among former NFL players, a population with relatively high levels of religious attendance who endure physically demanding occupations. Research shows that frequent religious service attenders tend to have better health, partly because of social connections formed through religious involvement. We analyzed a sample of 1029 former NFL players. Consistent with previous research, bivariate and multivariate OLS regression models show that frequent religious attenders have statistically significantly better self-rated health. However, this relationship is moderated by social ties. Respondents who scored lower on the social ties index exhibited a stronger significant relationship between frequent religious attendance and health; those scoring higher on the social ties index exhibited no relationship between frequent attendance and health. Future research should examine how benefits of religious attendance vary depending upon strength of social relationships., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Patterns of cognitive impairment in former American football players are uncertain because objective neuropsychological data are lacking. This study characterized the neuropsychological test performance of former college and professional football players., Methods: One hundred seventy male former football players (n=111 professional, n=59 college; 45-74 years) completed a neuropsychological test battery. Raw scores were converted to T-scores using age, sex, and education-adjusted normative data. A T-score ≤ 35 defined impairment. A domain was impaired if 2+ scores fell in the impaired range except for the language and visuospatial domains due to the limited number of tests., Results: Most football players had subjective cognitive concerns. On testing, rates of impairments were greatest for memory (21.2% two tests impaired), especially for recall of unstructured (44.7%) versus structured verbal stimuli (18.8%); 51.8% had one test impaired. 7.1% evidenced impaired executive functions; however, 20.6% had impaired Trail Making Test B. 12.1% evidenced impairments in the attention, visual scanning, and psychomotor speed domain with frequent impairments on Trail Making Test A (18.8%). Other common impairments were on measures of language (i.e., Multilingual Naming Test [21.2%], Animal Fluency [17.1%]) and working memory (Number Span Backward [14.7%]). Impairments on our tasks of visuospatial functions were infrequent., Conclusions: In this sample of former football players (most of whom had subjective cognitive concerns), there were diffuse impairments on neuropsychological testing with verbal memory being the most frequently impaired domain., (© 2023. The Author(s).)

Introduction: Neuronal hyperactivity is an early neuronal defect commonly observed in familial and sporadic Alzheimer's disease (AD), but the underlying mechanisms are unclear., Methods: We employed a ryanodine receptor 2 (RyR2) mutant mouse model harboring the R4496C +/- mutation that markedly increases the channel's open probability (Po) to determine the impact of increased RyR2 activity in neuronal function without AD gene mutations., Results: Genetically increasing RyR2 Po induced neuronal hyperactivity in vivo in anesthetized and awake mice. Increased RyR2 Po induced hyperactive behaviors, impaired learning and memory, defective dendritic spines, and neuronal cell death. Increased RyR2 Po exacerbated the onset of neuronal hyperexcitability and learning and memory impairments in 5xFAD mice., Discussion: Increased RyR2 Po exacerbates the onset of familial AD-associated neuronal dysfunction, and induces AD-like defects in the absence of AD-causing gene mutations, suggesting that RyR2-associated neuronal hyperactivity represents a common target for combating AD with or without AD gene mutations., (© 2021 the Alzheimer's Association.)

Epilepsy and neurodevelopmental disorders can arise from pathogenic variants of KCNQ (Kv7) channels. A patient with developmental and epileptic encephalopathy exhibited an in-frame deletion of histidine 260 on Kv7.2. Coexpression of Kv7.2 mutant (mut) subunits with Kv7.3 invoked a decrease in current density, a depolarizing shift in voltage for activation, and a decrease in membrane conductance. Biotinylation revealed an increased level of surface Kv7.2mut compared to Kv7.3 with no change in total membrane protein expression. Super-resolution and FRET imaging confirmed heteromeric channel formation and a higher expression density of Kv7.2mut. Cannabidiol (1 μM) offset the effects of Kv7.2mut by inducing a hyperpolarizing shift in voltage for activation independent of CB1 or CB2 receptors. These data reveal that the ability for cannabidiol to reduce the effects of a pathogenic Kv7.2 variant supports its use as a potential therapeutic to reduce seizure activity., Competing Interests: The authors declare no conflicts of interest., (Crown Copyright © 2022.)

The objective of this systematic review is to synthesize the relevant literature published after 2016 to ascertain the current landscape of science that relates mild traumatic brain injury (mTBI) to the onset of Alzheimer's disease and related dementias (ADRD) and identify areas of need for future research. We conducted database searches and retrieved articles that were published after 2016 that utilized cognitive assessments to understand the relationship between mTBI and ADRD. We identified eight relevant articles in the review process, four of which presented a significant relationship between mTBI and disease or cognitive impairment outcomes. The studies included in this systematic review underscore the need for future research investigating a possible causal relationship between mTBI and ADRDs given the high prevalence of mTBI among brain injury patients and the lack of literature specifically addressing this issue. Future research should standardize the definitions of mTBI, AD, and ADRDs to create reliable and reproducible results that more comprehensively capture the nuances of this relationship., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Neuronal signal transmission depends on the frequency, pattern, and timing of spike output, each of which are shaped by spike afterhyperpolarizations (AHPs). There are classically three post-spike AHPs of increasing duration categorized as fast, medium and slow AHPs that hyperpolarize a cell over a range of 10 ms to 30 s. Intensive early work on CA1 hippocampal pyramidal cells revealed that all three AHPs incorporate activation of calcium-gated potassium channels. The ionic basis for a fAHP was rapidly attributed to the actions of big conductance (BK) and the mAHP to small conductance (SK) or Kv7 potassium channels. In stark contrast, the ionic basis for a prominent slow AHP of up to 30 s duration remained an enigma for over 30 years. Recent advances in pharmacological, molecular, and imaging tools have uncovered the expression of a calcium-gated intermediate conductance potassium channel (IK, KCa3.1) in central neurons that proves to contribute to the slow AHP in CA1 hippocampal pyramidal cells. Together the data show that the sAHP arises in part from a core tripartite complex between Cav1.3 (L-type) calcium channels, ryanodine receptors, and IK channels at endoplasmic reticulum-plasma membrane junctions. Work on the sAHP in CA1 pyramidal neurons has again quickened pace, with identified contributions by both IK channels and the Na-K pump providing answers to several mysteries in the pharmacological properties of the sAHP., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sahu and Turner.)

Background: Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease that has been neuropathologically diagnosed in brain donors exposed to repetitive head impacts, including boxers and American football, soccer, ice hockey, and rugby players. CTE cannot yet be diagnosed during life. In December 2015, the National Institute of Neurological Disorders and Stroke awarded a seven-year grant (U01NS093334) to fund the "Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy (DIAGNOSE CTE) Research Project." The objectives of this multicenter project are to: develop in vivo fluid and neuroimaging biomarkers for CTE; characterize its clinical presentation; refine and validate clinical research diagnostic criteria (i.e., traumatic encephalopathy syndrome [TES]); examine repetitive head impact exposure, genetic, and other risk factors; and provide shared resources of anonymized data and biological samples to the research community. In this paper, we provide a detailed overview of the rationale, design, and methods for the DIAGNOSE CTE Research Project., Methods: The targeted sample and sample size was 240 male participants, ages 45-74, including 120 former professional football players, 60 former collegiate football players, and 60 asymptomatic participants without a history of head trauma or participation in organized contact sports. Participants were evaluated at one of four U.S. sites and underwent the following baseline procedures: neurological and neuropsychological examinations; tau and amyloid positron emission tomography; magnetic resonance imaging and spectroscopy; lumbar puncture; blood and saliva collection; and standardized self-report measures of neuropsychiatric, cognitive, and daily functioning. Study partners completed similar informant-report measures. Follow-up evaluations were intended to be in-person and at 3 years post-baseline. Multidisciplinary diagnostic consensus conferences are held, and the reliability and validity of TES diagnostic criteria are examined., Results: Participant enrollment and all baseline evaluations were completed in February 2020. Three-year follow-up evaluations began in October 2019. However, in-person evaluation ceased with the COVID-19 pandemic, and resumed as remote, 4-year follow-up evaluations (including telephone-, online-, and videoconference-based cognitive, neuropsychiatric, and neurologic examinations, as well as in-home blood draw) in February 2021., Conclusions: Findings from the DIAGNOSE CTE Research Project should facilitate detection and diagnosis of CTE during life, and thereby accelerate research on risk factors, mechanisms, epidemiology, treatment, and prevention of CTE., Trial Registration: NCT02798185., (© 2021. The Author(s).)

T-type calcium channels are important regulators of neuronal excitability. The mammalian brain expresses three T-type channel isoforms (Cav3.1, Cav3.2 and Cav3.3) with distinct biophysical properties that are critically regulated by temperature. Here, we test the effects of how temperature affects spike output in a reduced firing neuron model expressing specific Cav3 channel isoforms. The modeling data revealed only a minimal effect on baseline spontaneous firing near rest, but a dramatic increase in rebound burst discharge frequency for Cav3.1 compared to Cav3.2 or Cav3.3 due to differences in window current or activation/recovery time constants. The reduced response by Cav3.2 could optimize its activity where it is expressed in peripheral tissues more subject to temperature variations than Cav3.1 or Cav3.3 channels expressed prominently in the brain. These tests thus reveal that aspects of neuronal firing behavior are critically dependent on both temperature and T-type calcium channel subtype., (© 2021. The Author(s).)

Importance: In the US, dementia risk is higher in non-Hispanic Black individuals than in non-Hispanic White individuals. To evaluate progress toward reducing such disparities, tracking secular trends in racial disparities in dementia prevalence is essential., Objective: To examine whether relative racial disparities in dementia prevalence or incidence have changed in the US from 2000 to 2016., Design, Settings, and Participants: The Health and Retirement Study (HRS) is a nationally representative study of adults 50 years or older. New participants are recruited every 6 years, and study visits occur biennially. Approximately 17 000 to 22 000 respondents have been surveyed at each wave since 2000, achieving response rates of 81% to 89%. Data for this cohort study were obtained from non-Hispanic White and non-Hispanic Black participants aged 70 years and older from the 2000 to 2016 waves. For analyses of secular trends in racial disparities in dementia prevalence, each HRS wave was considered separately (range of participants meeting eligibility criteria in each wave, 6322-7579). For analyses of secular trends in racial disparities in dementia incidence, 7 subcohorts were created (range of participants meeting eligibility criteria in each subcohort, 5322-5961) following up people without dementia for 4 years from subcohort baseline visits in 2000, 2002, 2004, 2006, 2008, 2010, and 2012. Data were analyzed from October 2019 to August 2020., Exposures: Race based on self-response to closed-ended survey questions., Main Outcomes and Measures: Dementia status was determined using 3 algorithms with similar sensitivity and specificity across non-Hispanic White and Black participants. Disparities were characterized using ratio measures., Results: In this study, the mean age and percentage of male participants eligible for inclusion in analyses of racial disparities in dementia prevalence increased over time among non-Hispanic White participants (from 78.2 years and 40% in 2000 to 78.7 years and 44% in 2016) but remained steady in non-Hispanic Black participants during the same period (from 78.0 years and 37% in 2000 to 77.9 years and 38% in 2016). Prevalence ratios comparing Black and White participants ranged from approximately 1.5 to 1.9 across algorithms and years, whereas hazard ratios ranged from approximately 1.4 to 1.8. Although results suggest stable or declining dementia risk overall, there was no evidence suggesting change in relative racial disparities in dementia prevalence or incidence during follow-up., Conclusions and Relevance: This study did not find evidence to suggest that the ratio of dementia risk across Black and White individuals changed in the US between 2000 and 2016. Additional efforts to identify and mitigate the source of these disparities is warranted.

Objective: Examine associations between a range of sleep problems and academic performance in a national sample of collegiate athletes. Participants: Data were obtained from the National College Health Assessment of US college/university students from 2011-2014 ( N  = 8,312 collegiate athletes). Methods: Univariate comparisons for all sleep variables and demographics were stratified across GPA, using one-way ANOVA for continuous variables and chi-square for categorical variables. Multinomial logistic regression models, with GPA as outcome (reference = A) and sleep variable as predictor, were examined and adjusted for age, sex, and survey year. Ordinal regression examined a 1-level change in GPA associated with each sleep variable, adjusted for covariates. Results: Sleep difficulty was associated with increased likelihood of B/C averages. Initial-insomnia was associated with increased likelihood of B/C, and D/F averages. Tiredness was associated with increased likelihood of B/C, and D/F averages. Conclusions: Sleep problems are highly prevalent and associated with poorer academic performance in collegiate athletes.

Over the past decade, media outlets have drawn attention to some of the health consequences of playing in the National Football League (NFL), including how wear-and-tear and injuries accumulated during athletes' playing years can affect their physical, emotional, and behavioral health after retirement from professional sports. Through a secondary analysis of a cross-sectional telephone survey of former NFL athletes, this study estimated logistic regression models to assess the relationship between several forms of physical pain and anger attacks, controlling for binge drinking, signs of depression, functional limitations, NFL career duration, religious service attendance, and demographic characteristics (age, marital status, race, education, income, and wealth). The analytic sample included 1030 former NFL players. Neck pain, lower back pain, headaches/migraines, and the number of sites of pain were positively and significantly related to anger attacks. There was no significant association between joint pain and anger attacks. NFL career duration was negatively associated with anger attacks, as was religious service attendance. Future research should focus on factors that protect against affective aggression in former professional athletes and how protective factors can be adapted to the broader population.

Neuronal hyperactivity is an early primary dysfunction in Alzheimer's disease (AD) in humans and animal models, but effective neuronal hyperactivity-directed anti-AD therapeutic agents are lacking. Here we define a previously unknown mode of ryanodine receptor 2 (RyR2) control of neuronal hyperactivity and AD progression. We show that a single RyR2 point mutation, E4872Q, which reduces RyR2 open time, prevents hyperexcitability, hyperactivity, memory impairment, neuronal cell death, and dendritic spine loss in a severe early-onset AD mouse model (5xFAD). The RyR2-E4872Q mutation upregulates hippocampal CA1-pyramidal cell A-type K + current, a well-known neuronal excitability control that is downregulated in AD. Pharmacologically limiting RyR2 open time with the R-carvedilol enantiomer (but not racemic carvedilol) prevents and rescues neuronal hyperactivity, memory impairment, and neuron loss even in late stages of AD. These AD-related deficits are prevented even with continued β-amyloid accumulation. Thus, limiting RyR2 open time may be a hyperactivity-directed, non-β-amyloid-targeted anti-AD strategy., Competing Interests: Declaration of Interests We are planning to submit a Provisional Application for Patent, entitled “METHODS OF TREATING ALZHEIMER’S DISEASE OR DELAYING PROGRESSION THEREOF BY LIMITING RYANODINE RECEPTOR OPEN TIME.”, (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Objectives: Sleep difficulties are common among older adults and are associated with cognitive decline. We used data from a large, nationally representative longitudinal survey of adults aged older than 50 in the United States to examine the relationship between specific sleep difficulties and cognitive function over time., Research Design and Methods: Longitudinal data from the 2004-2014 waves of the Health and Retirement Study were used in the current study. We examined sleep difficulties and cognitive function within participants and across time ( n = 16 201). Sleep difficulty measures included difficulty initiating sleep, nocturnal awakenings, early morning awakenings, and waking up feeling rested from rarely/never (1) to most nights (3). The modified Telephone Interview for Cognitive Status was used to measure cognitive function. Generalized linear mixed models were used with time-varying covariates to examine the relationship between sleep difficulties and cognitive function over time., Results: In covariate-adjusted models, compared to "never" reporting sleep difficulty, difficulty initiating sleep "most nights" was associated with worse cognitive function over time (Year 2014: b = -0.40, 95% CI: -0.63 to -0.16, p < .01) as was difficulty waking up too early "most nights" (Year 2014: b = -0.31, 95% CI: -0.56 to -0.07, p < .05). In covariate-adjusted analyses, compared to "never" reporting waking up feeling rested, cognitive function was higher among those who reported waking up feeling rested "some nights" (Year 2010: b = 0.21, 95% CI: 0.02 to 0.40, p < .05)., Discussion and Implications: Our findings highlight an association between early morning awakenings and worse cognitive function, but also an association between waking up feeling rested and better cognitive function over time., (© The Author(s) 2020. Published by Oxford University Press on behalf of The Gerontological Society of America.)

Fragile X Syndrome results from a loss of Fragile X Mental Retardation Protein (FMRP). We now show that FMRP is a member of a Cav3-Kv4 ion channel complex that is known to regulate A-type potassium current in cerebellar granule cells to produce mossy fiber LTP. Mossy fiber LTP is absent in Fmr1 knockout (KO) mice but is restored by FMRP(1-297)-tat peptide. This peptide further rapidly permeates the blood-brain barrier to enter cells across the cerebellar-cortical axis that restores the balance of protein translation for at least 24 h and transiently reduces elevated levels of activity of adult Fmr1 KO mice in the Open Field Test. These data reveal that FMRP(1-297)-tat can improve function from the levels of protein translation to synaptic efficacy and behaviour in a model of Fragile X syndrome, identifying a potential therapeutic strategy for this genetic disorder.

The objective of this study was to analyze data from the National Football League Player Care Foundation Study of Retired NFL Players to understand potential risks for depressive symptoms in former athletes by investigating the relationship between pain and depressive symptoms in a multivariate context, while simultaneously exploring the potential connection with functional limitations. Descriptive statistics were used to describe the study sample and to conduct bivariate comparisons by race and age cohort. Linear regression models were conducted in the subsample of respondents reporting on depressive symptoms using the PHQ-9. Models examine the relationship of bodily pain, injury as a reason for retirement or not re-signing with a team, length of NFL career, sociodemographic characteristics, chronic conditions, and functional limitations to depression. Interaction terms tested whether race and age moderated the effect of bodily pain and functional limitations on depressive symptoms. Bivariate associations revealed no significant differences between younger and older former players in indicators of pain and only slightly higher functional limitations among younger former players. In the multivariate models, pain was significantly associated with depressive symptoms (β = 0.36; p < .01), net of a range of relevant controls. Adding an index of functional limitations reduced this association by nearly half (β = 0.20; p < .01) and functional limitations was significantly associated with depressive symptoms (β = 0.40; p < .01). No statistically significant interactions were found. Overall, bodily pain was strongly associated with depressive symptoms. After accounting for the effects of functional limitations, this association was notably reduced. These results may be useful in identifying aging-related physical declines in relatively younger adult men who may be at the greatest risk for depression. They highlight how physical functionality and activity may mitigate the risk of depression, even in the presence of significant bodily pain.

The excitability of CA1 hippocampal pyramidal cells is mediated by a slow AHP (sAHP) that responds to calcium increases by Cav1 calcium channels and ryanodine receptors (RyR). We used super-resolution and FRET microscopy to investigate the proximity and functional coupling among Cav1.3/Cav1.2, RyR2, and KCa3.1 potassium channels that contribute to the sAHP. dSTORM and FRET imaging shows that Cav1.3, RyR2, and KCa3.1 are organized as a triprotein complex that colocalizes with junctophilin (JPH) 3 and 4 proteins that tether the plasma membrane to the endoplasmic reticulum. JPH3 and JPH4 shRNAs dissociated a Cav1.3-RyR2-KCa3.1 complex and reduced the IsAHP. Infusing JPH3 and JPH4 antibodies into CA1 cells reduced IsAHP and spike accommodation. These data indicate that JPH3 and JPH4 proteins maintain a Cav1-RyR2-KCa3.1 complex that allows two calcium sources to act in tandem to define the activation properties of KCa3.1 channels and the IsAHP., (Crown Copyright © 2019. Published by Elsevier Inc. All rights reserved.)

Three small conductance calcium-activated potassium channel (SK) subunits have been cloned and found to preferentially form heteromeric channels when expressed in a heterologous expression system. The original cloning of the gene encoding the intermediate conductance calcium-activated potassium channel (IKCa) was termed SK4 because of the high homology between channel subtypes. Recent immunovisualization suggests that IKCa is expressed in the same subcellular compartments of some neurons as SK channel subunits. Stochastic optical reconstruction microscopy super-resolution microscopy revealed that coexpressed IKCa and SK1 channel subunits were closely associated, a finding substantiated by measurement of fluorescence resonance energy transfer between coexpressed fluorophore-tagged subunits. Expression of homomeric SK1 channels produced current that displayed typical sensitivity to SK channel inhibitors, while expressed IKCa channel current was inhibited by known IKCa channel blockers. Expression of both SK1 and IKCa subunits gave a current that displayed no sensitivity to SK channel inhibitors and a decreased sensitivity to IKCa current inhibitors. Single channel recording indicated that coexpression of SK1 and IKCa subunits produced channels with properties intermediate between those observed for homomeric channels. These data indicate that SK1 and IKCa channel subunits preferentially combine to form heteromeric channels that display pharmacological and biophysical properties distinct from those seen with homomeric channels., (Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics.)

Ca V 1 L-type calcium channels are key to regulating neuronal excitability, with the range of functional roles enhanced by interactions with calmodulin, accessory proteins, or CaMKII that modulate channel activity. In hippocampal pyramidal cells, a prominent elevation of Ca V 1 activity is apparent in late channel openings that can last for seconds following a depolarizing stimulus train. The current study tested the hypothesis that a reported interaction among Ca V 1.3 channels, the scaffolding protein densin, and CaMKII could generate a facilitation of channel activity that outlasts a depolarizing stimulus. We found that Ca V 1.3 but not Ca V 1.2 channels exhibit a long-duration calcium-dependent facilitation (L-CDF) that lasts up to 8 s following a brief 50 Hz stimulus train, but only when coexpressed with densin and CaMKII. To test the physiological role for Ca V 1.3 L-CDF, we coexpressed the intermediate-conductance KCa3.1 potassium channel, revealing a strong functional coupling to Ca V 1.3 channel activity that was accentuated by densin and CaMKII. Moreover, the Ca V 1.3-densin-CaMKII interaction gave rise to an outward tail current of up to 8 s duration following a depolarizing stimulus in both tsA-201 cells and male rat CA1 pyramidal cells. A slow afterhyperpolarization in pyramidal cells was reduced by a selective block of Ca V 1 channels by isradipine, a CaMKII blocker, and siRNA knockdown of densin, and spike frequency increased upon selective block of Ca V 1 channel conductance. The results are important in revealing a Ca V 1.3-densin-CaMKII interaction that extends the contribution of Ca V 1.3 calcium influx to a time frame well beyond a brief input train. SIGNIFICANCE STATEMENT Ca V 1 L-type calcium channels play a key role in regulating the output of central neurons by providing calcium influx during repetitive inputs. This study identifies a long-duration calcium-dependent facilitation (L-CDF) of Ca V 1.3 channels that depends on the scaffolding protein densin and CaMKII and that outlasts a depolarizing stimulus by seconds. We further show a tight functional coupling between Ca V 1.3 calcium influx and the intermediate-conductance KCa3.1 potassium channel that promotes an outward tail current of up to 8 s following a depolarizing stimulus. Tests in CA1 hippocampal pyramidal cells reveal that a slow AHP is reduced by blocking different components of the Ca V 1.3-densin-CaMKII interaction, identifying an important role for Ca V 1.3 L-CDF in regulating neuronal excitability., (Copyright © 2017 the authors 0270-6474/17/3711255-16$15.00/0.)

Calmodulin (CaM) is an important signaling molecule that regulates a vast array of cellular functions by activating second messengers involved in cell function and plasticity. Low voltage-activated calcium channels of the Cav3 family have the important role of mediating low threshold calcium influx, but were not believed to interact with CaM. We find a constitutive association between CaM and the Cav3.1 channel at rest that is lost through an activity-dependent and Cav3.1 calcium-dependent CaM dissociation. Moreover, Cav3 calcium influx is sufficient to activate αCaMKII in the cytoplasm in a manner that depends on an intact Cav3.1 C-terminus needed to support the CaM interaction. Our findings thus establish that T-type channel calcium influx invokes a novel dynamic interaction between CaM and Cav3.1 channels to trigger a signaling cascade that leads to αCaMKII activation.

Primary Objective: To preliminarily explore parents' health literacy and knowledge of youth sport league rules involving concussion education and training, and return-to-play protocols., Research Design and Methods: This study was guided by the Knowledge, Attitude and Practice (KAP) model of health knowledge to examine parents' concussion literacy, and understanding of concussion education and training, and return-to-play protocols in youth sports. The mixed-method design involved 119 participants; that included in-person (n=8) and telephone (n=4) interviews, and web-based surveys administered through Mechanical Turk via Qualtrics (n=98)., Main Outcomes and Results: Most respondents were not familiar with concussion protocols, but trusted coaches' knowledge in return-to-play rules. More than half of the respondents report that the return-to-play concussion criteria have not been clearly explained to them. The majority of respondents were not familiar with the CDC's 'Heads Up' online concussion training programme, nor were they familiar with any other educational/training tool. About one-fifth of the parents had conversations with a coach or medical staff about youth sport concussions., Conclusion: Parents have a general understanding of how to identify concussion symptoms, but lack knowledge of immediate steps to take following an incident other than seeking medical help.

Mossy fiber afferents to cerebellar granule cells form the primary synaptic relay into cerebellum, providing an ideal site to process signal inputs differentially. Mossy fiber input is known to exhibit a long-term potentiation (LTP) of synaptic efficacy through a combination of presynaptic and postsynaptic mechanisms. However, the specific postsynaptic mechanisms contributing to LTP of mossy fiber input is unknown. The current study tested the hypothesis that LTP induces a change in intrinsic membrane excitability of rat cerebellar granule cells through modification of Kv4 A-type potassium channels. We found that theta-burst stimulation of mossy fiber input in lobule 9 granule cells lowered the current threshold to spike and increases the gain of spike firing by 2- to 3-fold. The change in postsynaptic excitability was traced to hyperpolarizing shifts in both the half-inactivation and half-activation potentials of Kv4 that occurred upon coactivating NMDAR and group I metabotropic glutamatergic receptors. The effects of theta-burst stimulation on Kv4 channel control of the gain of spike firing depended on a signaling cascade leading to extracellular signal-related kinase activation. Under physiological conditions, LTP of synaptically evoked spike output was expressed preferentially for short bursts characteristic of sensory input, helping to shape signal processing at the mossy fiber-granule cell relay., Significance Statement: Cerebellar granule cells receive mossy fiber inputs that convey information on different sensory modalities and feedback from descending cortical projections. Recent work suggests that signal processing across multiple cerebellar lobules is controlled differentially by postsynaptic ionic mechanisms at the level of granule cells. We found that long-term potentiation (LTP) of mossy fiber input invoked a large increase in granule cell excitability by modifying the biophysical properties of Kv4 channels through a specific signaling cascade. LTP of granule cell output became evident in response to bursts of mossy fiber input, revealing that Kv4 control of intrinsic excitability is modified to respond most effectively to patterns of afferent input that are characteristic of physiological sensory patterns., (Copyright © 2016 the authors 0270-6474/16/3611196-12$15.00/0.)

Our previous work reported that KCa3.1 (IKCa) channels are expressed in CA1 hippocampal pyramidal cells and contribute to the slow afterhyperpolarization that regulates spike accommodation in these cells. The current report presents data from single cell RT-PCR that further reveals mRNA in CA1 cells that corresponds to the sequence of an IKCa channel from transmembrane segments 5 through 6 including the pore region, revealing the established binding sites for 4 different IKCa channel blockers. A comparison of methods to internally apply the IKCa channel blocker TRAM-34 shows that including the drug in an electrode from the onset of an experiment is unviable given the speed of drug action upon gaining access for whole-cell recordings. Together the data firmly establish IKCa channel expression in CA1 neurons and clarify methodological requirements to obtain a block of IKCa channel activity through internal application of TRAM-34.

Key Points: Cerebellar Purkinje cells project GABAergic inhibitory input to neurons of the deep cerebellar nuclei (DCN) that generate a rebound increase in firing, but the specific patterns of input that might elicit a rebound response have not been established. We used recordings of Purkinje cell firing obtained during perioral whisker stimulation in vivo to create a physiological stimulus template to activate Purkinje cell afferents in vitro. DCN cell bursts were evoked by the stimulus pattern but not in relation to the perioral whisker stimulus, complex spikes or regular patterns within the Purkinje cell record. Reverse correlation revealed that bursts were triggered by an elevation-pause pattern of Purkinje cell firing, with pause duration a key factor in burst generation. Our data identify for the first time a physiological pattern of Purkinje cell input that can be encoded by the generation of rebound bursts in DCN cells., Abstract: The end result of signal processing in cerebellar cortex is encoded in the output of Purkinje cells that project inhibitory input to deep cerebellar nuclear (DCN) neurons. DCN cells can respond to a period of inhibition in vitro with a rebound burst of firing, yet the optimal physiological pattern of Purkinje cell input that might evoke a rebound burst is unknown. The current study used spike trains recorded from rat Purkinje cells in response to perioral stimuli in vivo to create a physiological pattern to stimulate Purkinje cell axons in vitro. The perioral stimulus-evoked Purkinje cell firing pattern proved to be virtually ineffective in evoking a rebound burst despite the ability to reliably evoke rebounds using a traditional brief 100 Hz stimulus. Similarly, neither complex spike firing nor Purkinje cell patterns identified by CV2 analysis were reliably associated with rebound bursts. Reverse correlation revealed that the optimal Purkinje cell input to evoke a rebound burst was a sequential increase in mean firing rate of at least 30 Hz above baseline over 250 ms followed by a reduction of 40-60 Hz below baseline for up to 500 ms. The most important factor was the duration of a pause in Purkinje cell firing that allowed DCN cells to recover from a state of net inhibitory influence. These data indicate that physiological patterns of Purkinje cell firing can elicit rebound bursts in DCN cells in vitro, with pauses in Purkinje cell firing rate acting as a key stimulus for DCN cell rebound responses., (© 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.)

Control over the frequency and pattern of neuronal spike discharge depends on Ca2+-gated K+ channels that reduce cell excitability by hyperpolarizing the membrane potential. The Ca2+-dependent slow afterhyperpolarization (sAHP) is one of the most prominent inhibitory responses in the brain, with sAHP amplitude linked to a host of circuit and behavioral functions, yet the channel that underlies the sAHP has defied identification for decades. Here, we show that intermediate-conductance Ca2+-dependent K+ (IKCa) channels underlie the sAHP generated by trains of synaptic input or postsynaptic stimuli in CA1 hippocampal pyramidal cells. These findings are significant in providing a molecular identity for the sAHP of central neurons that will identify pharmacological tools capable of potentially modifying the several behavioral or disease states associated with the sAHP.

Objective. To understand the relationships between participation in different types of leisure time sport activity and adolescent obesity, and how those relationships might differ based on race, gender, and household income. Methods. Data consisted of 6667 students that took part in the 1999 to 2006 National Health and Nutrition Examination Survey. The authors used adjusted Wald tests to examine differences in the prevalence of obesity (body mass index >95th percentile for age and sex) by sport for boys and girls separately. Results. Among adolescent youth age 12 to 19 years, 16.6% of male leisure time sport participants and 15.3% of female sport participants were obese, compared with 23.6% for male nonathlete participant-in-other-activities and 17.0% obesity rate for female nonathlete/participant-in-other-activities. For both males and females, reported participation in leisure time sports decreased between middle school and high school, and this reduction was associated with higher body mass index.

The expression pattern and functional roles for calcium-activated potassium channels of the KCa2.x family and KCa1.1 have been extensively examined in central neurons. Recent work indicates that intermediate conductance calcium-activated potassium channels (KCa3.1) are also expressed in central neurons of the cerebellum and spinal cord. The current study used immunocytochemistry and GFP linked to KCNN4 promoter activity in a transgenic mouse to determine the expression pattern of KCa3.1 channels in rat or mouse neocortex, hippocampus, thalamus, and cerebellum. KCa3.1 immunolabel and GFP expression were closely matched and detected in both excitatory and inhibitory cells of all regions examined. KCa3.1 immunolabel was localized primarily to the somatic region of excitatory cells in cortical structures but at the soma and over longer segments of dendrites of cells in deep cerebellar nuclei. More extensive labeling was apparent for inhibitory cells at the somatic and dendritic level with no detectable label associated with axon tracts or regions of intense synaptic innervation. The data indicate that KCa3.1 channels are expressed in the CNS with a differential pattern of distribution between cells, suggesting important functional roles for these calcium-activated potassium channels in regulating the excitability of central neurons.

The cerebellum receives sensory information by mossy fiber input from a multitude of sources that require differential signal processing. A compartmentalization of function begins with the segregation of mossy fibers across 10 distinct lobules over the rostrocaudal axis, with tactile receptor afferents prevalent in anterior lobules and vestibular input in caudal lobules. However, it is unclear how these unique signals might be differentially processed at the circuit level across the cerebellum. As granule cells receive mossy fiber input, they represent a key stage at which postsynaptic mechanisms could influence signal processing. Granule cells express an A-type current mediated by Kv4 potassium channels that modify the latency and frequency of spike output. The current study examined the potential for a Cav3 calcium-Kv4 channel complex to regulate the response of granule cells to mossy fiber input in lobules 2 and 9 of the rat cerebellum. Similar A-type currents were recorded in both regions, but the Cav3 calcium current was expressed at a substantially higher density in lobule 9 cells, acting to increase A-type current availability through its influence on Kv4 voltage for inactivation. The difference in excitability imparted by Cav3-Kv4 interactions proves to allow lobule 2 granule cells to respond more effectively to tactile stimulus-like burst input and lobule 9 cells to slow shifts in input frequency characteristic of vestibular input. The expression pattern of Cav3 channels and its control of Kv4 availability thus provides a novel means of processing widely different forms of sensory input across cerebellar lobules., (Copyright © 2014 the authors 0270-6474/14/348800-13$15.00/0.)

The electrical output of neurons relies critically on voltage- and calcium-gated ion channels. The traditional view of ion channels is that they operate independently of each other in the plasma membrane in a manner that could be predicted according to biophysical characteristics of the isolated current. However, there is increasing evidence that channels interact with each other not just functionally but also physically. This is exemplified in the case of Cav3 T-type calcium channels, where new work indicates the ability to form signaling complexes with different types of calcium-gated and even voltage-gated potassium channels. The formation of a Cav3-K complex provides the calcium source required to activate KCa1.1 or KCa3.1 channels and, furthermore, to bestow a calcium-dependent regulation of Kv4 channels via associated KChIP proteins. Here, we review these interactions and discuss their significance in the context of neuronal firing properties.

T-type calcium channels of the Cav3 family are unique among voltage-gated calcium channels due to their low activation voltage, rapid inactivation, and small single channel conductance. These special properties allow Cav3 calcium channels to regulate neuronal processing in the subthreshold voltage range. Here, we review two different subthreshold ion channel interactions involving Cav3 channels and explore the ability of these interactions to expand the functional roles of Cav3 channels. In cerebellar Purkinje cells, Cav3 and intermediate conductance calcium-activated potassium (IKCa) channels form a novel complex which creates a low voltage-activated, transient outward current capable of suppressing temporal summation of excitatory postsynaptic potentials (EPSPs). In large diameter neurons of the deep cerebellar nuclei, Cav3-mediated calcium current (I T) and hyperpolarization-activated cation current (I H) are activated during trains of inhibitory postsynaptic potentials. These currents have distinct, and yet synergistic, roles in the subthreshold domain with I T generating a rebound burst and I H controlling first spike latency and rebound spike precision. However, by shortening the membrane time constant the membrane returns towards resting value at a faster rate, allowing I H to increase the efficacy of I T and increase the range of burst frequencies that can be generated. The net effect of Cav3 channels thus depends on the channels with which they are paired. When expressed in a complex with a KCa channel, Cav3 channels reduce excitability when processing excitatory inputs. If functionally coupled with an HCN channel, the depolarizing effect of Cav3 channels is accentuated, allowing for efficient inversion of inhibitory inputs to generate a rebound burst output. Therefore, signal processing relies not only on the activity of individual subtypes of channels but also on complex interactions between ion channels whether based on a physical complex or by indirect effects on membrane properties.

Three novel Pb oxyhalides, Pb3[O10Pb20](GeO4)4Cl10 (1), [O16Pb22][OPb](OH)I10(I,Br)(H2O) (2), and Pb5.5Si0.5O6Cl (3), have been prepared by high-temperature solid-state reactions (1 and 3) and hydrothermal method (2). The structure of 1 is based upon novel [O10Pb20](20+) layers of edge- and corner-sharing oxocentered OPb4 tetrahedra with cavities occupied by the GeO4 tetrahedral anions. The interlayer space contains low-occupied Pb sites and Cl(-) anions. The structure of 2 contains unique [O16Pb22][12+] layers of edge-sharing OPb4 tetrahedra with X(-) ions (X = I, Br) in and in between the layers. The structure of 3 is the first example of the Pb oxyhalide with the 3:1 ratio between the O-Pb and X sheets (X = halide). The unprecedented structure topologies and architectures observed in the title compounds are closely related to those observed in rare natural Pb oxyhalides that have no synthetic analogues to date.