Microglial MyD88-dependent pathways are regulated in a sex specific manner in the context of HMGB1-induced anxiety.

Chronic stress is a major risk factor for development and recurrence of anxiety disorders. Chronic stress has been shown to impact the immune system, causing microglial activation in the medial prefrontal cortex (mPFC), a brain region involved in the pathogenesis of anxiety. HMGB1 is both an established modulator of neuronal firing and a potent pro-inflammatory stimulus that is released from neuronal and non-neuronal cells following stress. HMGB1 in the context of stress acts as a danger associated molecular pattern (DAMP) instigating robust proinflammatory responses throughout the brain; so much so, that localized drug delivery of HMGB1 alters behavior in the absence of any other forms of stress i.e. social isolation, or behavioral stress models. Few studies have investigated the molecular mechanisms which underlie HMGB1 associated behavioral effects in a cell-specific manner. The aim of this study is to investigate cellular and molecular mechanisms underlying HMGB1 induced behavioral dysfunction with regards to cell-type specificity and potential sex differences. Here, we report that both male and female mice exhibited anxiety-like behavior following increased HMGB1 in the mPFC as well as changes in microglial morphology. However, only female mice showed microglial activation characterized by increased phagocytic capacity and decreased Tmem119 expression. Moreover, when measuring RNA from isolated microglia and non-microglial cells from the frontal cortex we found that female HMGB1 treated mice displayed a robust increase of RAGE and MyD88. Given these findings, to further investigate the underlying molecular mechanisms associated with HMGB1 induced anxiety-like behavior and microglia activation in mice, we used cKO (conditional knockout) mice with conditional deletion of MyD88 in microglia and repeated the paradigm. For males, we saw that the genetic manipulation did not prevent behavioral deficits in response to HMGB1 treatment. However, female cKO mice were protected from HMGB1-induced behavioral deficits. This study supports the hypothesis that the MyD88 signaling in microglia may be a crucial mediator of stress response in adult female mice.

Electome network factors: Capturing emotional brain networks related to health and disease.

Therapeutic development for mental disorders has been slow despite the high worldwide prevalence of illness. Unfortunately, cellular and circuit insights into disease etiology have largely failed to generalize across individuals that carry the same diagnosis, reflecting an unmet need to identify convergent mechanisms that would facilitate optimal treatment. Here, we discuss how mesoscale networks can encode affect and other cognitive processes. These networks can be discovered through electrical functional connectome (electome) analysis, a method built upon explainable machine learning models for analyzing and interpreting mesoscale brain-wide signals in a behavioral context. We also outline best practices for identifying these generalizable, interpretable, and biologically relevant networks. Looking forward, translational electome analysis can span species and various moods, cognitive processes, or other brain states, supporting translational medicine. Thus, we argue that electome analysis provides potential translational biomarkers for developing next-generation therapeutics that exhibit high efficacy across heterogeneous disorders.

Estimating a brain network predictive of stress and genotype with supervised autoencoders.

Targeted brain stimulation has the potential to treat mental illnesses. We develop an approach to help design protocols by identifying relevant multi-region electrical dynamics. Our approach models these dynamics as a superposition of latent networks, where the latent variables predict a relevant outcome. We use supervised autoencoders (SAEs) to improve predictive performance in this context, describe the conditions where SAEs improve predictions, and provide modelling constraints to ensure biological relevance. We experimentally validate our approach by finding a network associated with stress that aligns with a previous stimulation protocol and characterizing a genotype associated with bipolar disorder.

An aging-susceptible circadian rhythm controls cutaneous antiviral immunity.

Aged skin is prone to viral infections, but the mechanisms responsible for this immunosenescent immune risk are unclear. We observed that aged murine and human skin expressed reduced levels of antiviral proteins (AVPs) and circadian regulators, including Bmal1 and Clock. Bmal1 and Clock were found to control rhythmic AVP expression in skin, and such circadian control of AVPs was diminished by disruption of immune cell IL-27 signaling and deletion of Bmal1/Clock genes in mouse skin, as well as siRNA-mediated knockdown of CLOCK in human primary keratinocytes. We found that treatment with the circadian-enhancing agents nobiletin and SR8278 reduced infection of herpes simplex virus 1 in epidermal explants and human keratinocytes in a BMAL1/CLOCK-dependent manner. Circadian-enhancing treatment also reversed susceptibility of aging murine skin and human primary keratinocytes to viral infection. These findings reveal an evolutionarily conserved and age-sensitive circadian regulation of cutaneous antiviral immunity, underscoring circadian restoration as an antiviral strategy in aging populations.

Juneteenth in STEMM and the barriers to equitable science.

We are 52 Black scientists. Here, we establish the context of Juneteenth in STEMM and discuss the barriers Black scientists face, the struggles they endure, and the lack of recognition they receive. We review racism's history in science and provide institutional-level solutions to reduce the burdens on Black scientists.

An Aging-Susceptible Circadian Rhythm Controls Cutaneous Antiviral Immunity.

Aged skin is prone to viral infections, but the mechanisms responsible for this immunosenescent immune risk are unclear. We observed that aged murine and human skin expressed reduced antiviral proteins (AVPs) and circadian regulators including Bmal1 and Clock. Bmal1 and Clock were found to control rhythmic AVP expression in skin and such circadian-control of AVPs was diminished by disruption of immune cell interleukin 27 signaling and deletion of Bmal1/Clock genes in mouse skins, as well as siRNA-mediated knockdown of CLOCK in human primary keratinocytes. We found that treatment of circadian enhancing agents, nobiletin and SR8278, reduced infection of herpes simplex virus 1 (HSV1) in epidermal explants and human keratinocytes in a Bmal1/Clock-dependent manner. Circadian enhancing treatment also reversed susceptibility of aging murine skin and human primary keratinocytes to viral infection. These findings reveal an evolutionarily conserved and age-sensitive circadian regulation of cutaneous antiviral immunity, underscoring circadian restoration as an antiviral strategy in aging populations.

Structural Racism in Psychiatric Research Careers: Eradicating Barriers to a More Diverse Workforce.

Investigators from minoritized backgrounds are underrepresented in psychiatric research. That underrepresentation contributes to disparities in outcomes of access to mental health care. Drawing on lived experience, scholarly qualitative reports, and empirical data, the authors review how the underrepresentation of minoritized researchers arises from interlocking, self-reinforcing effects of structural biases in our research training and funding institutions. Minoritized researchers experience diminished early access to advanced training and opportunities, stereotype threats and microaggressions, isolation due to lack of peers and senior mentors, decreased access to early funding, and unique community and personal financial pressures. These represent structural racism-a system of institutional assumptions and practices that perpetuates race-based disparities, in spite of those institutions' efforts to increase diversity and in contradiction to the values that academic leaders outwardly espouse. The authors further review potential approaches to reversing these structural biases, including undergraduate-focused research experiences, financial support for faculty who lead training/mentoring programs, targeted mentoring through scholarly societies, better use of federal diversity supplement funding, support for scientific reentry, cohort building, diversity efforts targeting senior leadership, and rigorous examination of hiring, compensation, and promotion practices. Several of these approaches have empirically proven best practices and models for dissemination. If implemented alongside outcome measurement, they have the potential to reverse decades of structural bias in psychiatry and psychiatric research.

Advancing workforce diversity by leveraging the Clinical and Translational Science Awards (CTSA) program.

Clinical trials continue to disproportionately underrepresent people of color. Increasing representation of diverse backgrounds among clinical research personnel has the potential to yield greater representation in clinical trials and more efficacious medical interventions by addressing medical mistrust. In 2019, North Carolina Central University (NCCU), a Historically Black College and University with a more than 80% underrepresented student population, established the Clinical Research Sciences Program with support from the Clinical and Translational Science Awards (CTSA) program at neighboring Duke University. This program was designed to increase exposure of students from diverse educational, racial, and ethnic backgrounds to the field of clinical research, with a special focus on health equity education. In the first year, the program graduated 11 students from the two-semester certificate program, eight of whom now hold positions as clinical research professionals. This article describes how leveraging the CTSA program helped NCCU build a framework for producing a highly trained, competent, and diverse workforce in clinical research responsive to the call for increased diversity in clinical trial participation.

Gender, Racial, and Ethnic and Inequities in Receipt of Multiple National Institutes of Health Research Project Grants.

Importance: Diversity in the biomedical research workforce is essential for addressing complex health problems. Female investigators and investigators from underrepresented ethnic and racial groups generate novel, impactful, and innovative research, yet they are significantly underrepresented among National Institutes of Health (NIH) investigators. Objective: To examine the gender, ethnic, and racial distribution of super NIH investigators who received 3 or more concurrent NIH grants. Design, Setting, and Participants: This cross-sectional study included a national cohort of NIH-funded principal investigators (PIs) from the NIH Information for Management, Planning, Analysis, and Coordination (IMPAC II) database from 1991 to 2020. Exposures: Self-identified gender, race and ethnicity, annual number of NIH grant receipt, career stage, and highest degree. Main Outcomes and Measures: Distribution of investigators receiving 3 or more research project grants, referred to as super principal investigators (SPIs), by gender, race, and ethnicity. Results: Among 33 896 investigators in fiscal year 2020, 7478 (22.01%) identified as Asian, 623 (1.8%) as Black, 1624 (4.8%) as Hispanic, and 22 107 (65.2%) as White; 21 936 (61.7%) identified as men; and 8695 (35.3%) were early-stage investigators. Between 1991 and 2020, the proportion of SPIs increased 3-fold from 704 (3.7%) to 3942 (11.3%). However, SPI status was unequal across gender, ethnic, and racial groups. Women and Black PIs were significantly underrepresented among SPIs, even after adjusting for career stage and degree, and were 34% and 40% less likely than their male and White colleagues, respectively, to be an SPI. Black women PIs were the least likely to be represented among SPIs and were 71% less likely to attain SPI status than White men PIs (adjusted odds ratio, 0.29; 95% CI, 0.21-0.41). Conclusions and Relevance: In this cross-sectional study of a national cohort of NIH-funded investigators, the gender, ethnic, and racial gaps in receipt of multiple research project grants among NIH investigators was clearly apparent and warrants further investigation and interventions.

A novel cross-institutional college internship program to train future diverse leaders in clinical research with data-driven approaches to assess impact.

The field of Clinical Research, like many other scientific disciplines, has struggled to recruit and retain talented researchers from diverse communities. While there is a strong history of documenting the problem, having a diverse and inclusive workforce is hindered by the lack of data-driven approaches, cross-institutional partnerships, access to mentors, and positive immersive experiences for people from underrepresented groups. Here, we describe a novel initiative for North Carolina Central University Clinical Research Sciences Program (NCCU-CRSP) student interns to partner with Duke University to have immersive clinical and pre-clinical research training in a 15-week internship as the culminating experience towards their degree for a Bachelor of Science in Clinical Research. The goals of the internship are: 1) to give hands-on training to enhance the impact of classroom-based learning, 2) broaden their understanding of the wide swath of positions available to them, 3) promote their sense of self-efficacy, confidence, science identity, research identity, and connections to the pre-clinical and clinical community, and 4) prepare them to be workforce ready upon graduating. The students dedicate 75% of their time to clinical research with Duke University at Pickett Road and 25% to pre-clinical research in the Collective for Psychiatric Neuroengineering in the Duke Psychiatry Department of the School of Medicine. They will also receive eight 1-h professional development training sessions from the Duke-NCCU Clinical and Translational Science Initiative's Workforce Development Team and five 1-h sessions based on the Entering Research Curriculum developed by the Center for the Improvement of Mentored Experiences in Research (CIMER). Finally, they will be brought in as a cohort and coached on peer mentoring and mutual support frameworks to enhance their sense of community. These student-interns will perform pre- and post-internship self-assessment surveys to quantify their self-efficacy, feelings of belonging, access to research opportunities and mentors, and to give details of their future education and career goals. We will evaluate the impact of the internship using validated tools and apply these findings for future optimization of program design and tactical advice for other programs with shared missions. Furthermore, we will email them on an annual basis with follow-up surveys to assess the longitudinal impact of this internship program, their educational experiences at NCCU, what job titles they hold, how prepared they feel for their roles, and what they hope their future career trajectory will be. Collectively, these approaches will apply theoretical frameworks developed by social and cognitive psychology, vocational theory, and educational research to clinical research training with the goals of recruiting and training talented and diverse leaders within clinical research. We hope that by evaluating our successes, failures, strengths, and liabilities through empirically derived evidence we will also inspire future studies that use data-driven approaches to elevate our approaches as we work together to train and recruit talented researchers from diverse communities into our scientific enterprise and to launch them with more in-depth experiential learning that will empower them to succeed.

Prenatal environmental stressors impair postnatal microglia function and adult behavior in males.

Gestational exposure to environmental toxins and socioeconomic stressors is epidemiologically linked to neurodevelopmental disorders with strong male bias, such as autism. We model these prenatal risk factors in mice by co-exposing pregnant dams to an environmental pollutant and limited-resource stress, which robustly activates the maternal immune system. Only male offspring display long-lasting behavioral abnormalities and alterations in the activity of brain networks encoding social interactions. Cellularly, prenatal stressors diminish microglial function within the anterior cingulate cortex, a central node of the social coding network, in males during early postnatal development. Precise inhibition of microglial phagocytosis within the anterior cingulate cortex (ACC) of wild-type (WT) mice during the same critical period mimics the impact of prenatal stressors on a male-specific behavior, indicating that environmental stressors alter neural circuit formation in males via impairing microglia function during development.

Brain-wide electrical dynamics encode individual appetitive social behavior.

The architecture whereby activity across many brain regions integrates to encode individual appetitive social behavior remains unknown. Here we measure electrical activity from eight brain regions as mice engage in a social preference assay. We then use machine learning to discover a network that encodes the extent to which individual mice engage another mouse. This network is organized by theta oscillations leading from prelimbic cortex and amygdala that converge on the ventral tegmental area. Network activity is synchronized with cellular firing, and frequency-specific activation of a circuit within this network increases social behavior. Finally, the network generalizes, on a mouse-by-mouse basis, to encode individual differences in social behavior in healthy animals but fails to encode individual behavior in a 'high confidence' genetic model of autism. Thus, our findings reveal the architecture whereby the brain integrates distributed activity across timescales to encode an appetitive brain state underlying individual differences in social behavior.

Regulation of sensorimotor gating via Disc1/Huntingtin-mediated Bdnf transport in the cortico-striatal circuit.

Sensorimotor information processing underlies normal cognitive and behavioral traits and has classically been evaluated through prepulse inhibition (PPI) of a startle reflex. PPI is a behavioral dimension deregulated in several neurological and psychiatric disorders, yet the mechanisms underlying the cross-diagnostic nature of PPI deficits across these conditions remain to be understood. To identify circuitry mechanisms for PPI, we performed circuitry recording over the prefrontal cortex and striatum, two brain regions previously implicated in PPI, using wild-type (WT) mice compared to Disc1-locus-impairment (LI) mice, a model representing neuropsychiatric conditions. We demonstrated that the corticostriatal projection regulates neurophysiological responses during the PPI testing in WT, whereas these circuitry responses were disrupted in Disc1-LI mice. Because our biochemical analyses revealed attenuated brain-derived neurotrophic factor (Bdnf) transport along the corticostriatal circuit in Disc1-LI mice, we investigated the potential role of Bdnf in this circuitry for regulation of PPI. Virus-mediated delivery of Bdnf into the striatum rescued PPI deficits in Disc1-LI mice. Pharmacologically augmenting Bdnf transport by chronic lithium administration, partly via phosphorylation of Huntingtin (Htt) serine-421 and its integration into the motor machinery, restored striatal Bdnf levels and rescued PPI deficits in Disc1-LI mice. Furthermore, reducing the cortical Bdnf expression negated this rescuing effect of lithium, confirming the key role of Bdnf in lithium-mediated PPI rescuing. Collectively, the data suggest that striatal Bdnf supply, collaboratively regulated by Htt and Disc1 along the corticostriatal circuit, is involved in sensorimotor gating, highlighting the utility of dimensional approach in investigating pathophysiological mechanisms across neuropsychiatric disorders.

Understanding the biological basis of psychiatric disease: What's next?

Psychiatric disease is one of the greatest health challenges of our time. The pipeline for conceptually novel therapeutics remains low, in part because uncovering the biological mechanisms of psychiatric disease has been difficult. We asked experts researching different aspects of psychiatric disease: what do you see as the major urgent questions that need to be addressed? Where are the next frontiers, and what are the current hurdles to understanding the biological basis of psychiatric disease?

Measuring Nonapoptotic Caspase Activity with a Transgenic Reporter in Mice.

The protease caspase-3 is a key mediator of apoptotic programmed cell death. But weak or transient caspase activity can contribute to neuronal differentiation, axonal pathfinding, and synaptic long-term depression. Despite the importance of sublethal, or nonapoptotic, caspase activity in neurodevelopment and neural plasticity, there has been no simple method for mapping and quantifying nonapoptotic caspase activity (NACA) in rodent brains. We therefore generated a transgenic mouse expressing a highly sensitive and specific fluorescent reporter of caspase activity, with peak signal localized to the nucleus. As a proof of concept, we first obtained evidence that NACA influences neurophysiology in an amygdalar circuit. Then focusing on the amygdala, we were able to quantify a sex-specific persistent elevation in caspase activity in females after restraint stress. This simple in vivo caspase activity reporter will facilitate systems-level studies of apoptotic and nonapoptotic phenomena in behavioral and pathologic models.

Directed Spectral Measures Improve Latent Network Models Of Neural Populations.

Systems neuroscience aims to understand how networks of neurons distributed throughout the brain mediate computational tasks. One popular approach to identify those networks is to first calculate measures of neural activity (e.g. power spectra) from multiple brain regions, and then apply a linear factor model to those measures. Critically, despite the established role of directed communication between brain regions in neural computation, measures of directed communication have been rarely utilized in network estimation because they are incompatible with the implicit assumptions of the linear factor model approach. Here, we develop a novel spectral measure of directed communication called the Directed Spectrum (DS). We prove that it is compatible with the implicit assumptions of linear factor models, and we provide a method to estimate the DS. We demonstrate that latent linear factor models of DS measures better capture underlying brain networks in both simulated and real neural recording data compared to available alternatives. Thus, linear factor models of the Directed Spectrum offer neuroscientists a simple and effective way to explicitly model directed communication in networks of neural populations.

Revising the a Priori Hypothesis: Systemic Racism Has Penetrated Scientific Funding.

To manifest our sincerest aspirations to "enhance health, lengthen life, and reduce illness and disability," the US biomedical research enterprise must directly confront the reality of structural racism in scientific funding and the widespread denial of its existence. I believe that moment in American history has, at long last, arrived.

Missing in Action: African Ancestry Brain Research.

Individuals of African ancestry have been starkly underrepresented in the pursuit of personalized medicine for brain illnesses. The African Ancestry Neuroscience Research Initiative will seek to generate much-needed brain gene and protein expression profiles for people of African ancestry.