The significance of meaning: why do over 90% of behavioral neuroscience results fail to translate to humans, and what can we do to fix it?

The complexity of socially transmitted food preferences in rodents: a model for human epistemic trust?

Social safety learning refers to the process by which animals indirectly learn about the safety of novel stimuli. This process is critical when rodents decide what to eat since they lack the capacity to vomit, reducing their ability to expel ingested toxins. Consequently, rodents display neophobia when encountering novel food, but are more likely to eat the food when a conspecific signals its safety. This natural behavior is modeled using the social transmission of food preference (STFP) paradigm. Based on behavioral and neural insights into STFP, I argue in the current work that its acquisition may involve cognitive processes that extend beyond social safety learning. Specifically, I argue that STFP acquisition may parallel functional aspects of human epistemic trust. Epistemic trust refers to trust in communicated knowledge, enabling humans to learn from, adapt to, and respond to their (social) environment. This perspective could position the STFP paradigm as a valuable tool to investigate the neurobiology of cognitive processes that may be relevant to human epistemic trust. Given the importance of epistemic trust in therapeutic settings, understanding its neurobiology may have direct clinical implications.

Organoid-Guided Precision Medicine: From Bench to Bedside

Organoid technology, as an emerging field within biotechnology, has demonstrated transformative potential in advancing precision medicine. This review systematically outlines the translational trajectory of organoids from bench to bedside, emphasizing their construction methodologies, key regulatory factors, and multifaceted applications in personalized healthcare. By recapitulating physiological architectures and disease phenotypes through three-dimensional culture systems, organoids leverage natural and synthetic scaffolds, stem cell sources, and spatiotemporal cytokine regulation to model tissue-specific microenvironments. Diverse organoid types-including skin, intestinal, lung, and tumor organoids-have facilitated breakthroughs in modeling tissue development, drug efficacy and toxicity screening, disease pathogenesis studies, and patient-tailored diagnostics. For instance, patient-derived tumor organoids preserve tumor heterogeneity and genomic profiles, serving as predictive platforms for individualized chemotherapy responses. In precision medicine, organoid-guided multiomics analyses identify actionable biomarkers and resistance mechanisms, while clustered regularly interspaced short palindromic repeats-based functional screens optimize therapeutic targeting. Despite preclinical successes, challenges persist in standardization, vascularization, and ethical considerations. Future integration of artificial intelligence, microfluidics, and spatial transcriptomics will enhance organoid scalability, reproducibility, and clinical relevance. By bridging molecular insights with patient-specific therapies, organoids are poised to revolutionize precision medicine, offering dynamic platforms for drug development, regenerative strategies, and individualized treatment paradigms.

Crossing the Valley of Death in Spinal Cord Injury: Learning from Successful Translators

A straightforward path to successful scientific translation remains uncharted, particularly in a complex progressive condition such as spinal cord injury (SCI), which affects multiple body functions simultaneously. Evolving regulatory requirements add to the complexity and expense of attaining a treatment that is both safe and efficacious. Although rare, there are examples of SCI scientists who have successfully navigated the "valley of death" from discovery science to completed clinical trials. This article reflects the translational journey of five SCI scientists who have encountered similar and different scenarios while striving to launch or complete a clinical trial. Learning from these experiences has identified lessons learned and gaps, particularly with respect to funding and support for SCI translation.

Illuminating the Shadows of Neuroscience: How Curiosity and Courage Redefine Research Models and Mentorship

Scientific progress often hinges on the courage to question conventional models and embrace exploratory research. This commentary examines the importance of curiosity-driven science by drawing on historical and contemporary examples, from Darwin's unconventional research methodologies to modern neuroscience investigations that challenge the constraints of traditional laboratory environments. An over-reliance on predictable, controlled conditions-particularly in select rodent models-has potentially limited the translational impact of neuroscience. By exploring novel research paradigms, including raccoon neural investigations and rodent-driven vehicles (ROVs), the value of expanding research models to incorporate diverse species and environments is examined. As neuroscience advances, the field must move beyond the metaphorical lamp post, venturing into uncharted territory to fully capture the complexity of neurobiological variables. By fostering a culture of discovery over predictability-supported by innovative and exploratory mentoring approaches-we can illuminate new frontiers in neuroscience and develop transformative insights for mental health and beyond.

The utility of animal models to inform the next generation of human space exploration

Animals have played a vital role in every stage of space exploration, from early sub-orbital flights to contemporary missions. New physiological and psychological challenges arise with plans to venture deeper into the solar system. Advances in chimeric and knockout animal models, along with genetic modification techniques have enhanced our ability to study the effects of microgravity in greater detail. However, increased investment in the purposeful design of habitats and payloads, as well as in AI-enhanced behavioral monitoring in orbit can better support the ethical and effective use of animals in deep space research.

Convergent effects of synthetic glucocorticoid dexamethasone and amyloid beta in human olfactory neurosphere-derived cells

Stressful life events and glucocorticoid (stress) hormones appear to increase the risk of Alzheimer's disease and hasten its progression, but the reasons for this remain unclear. One potential explanation is that when amyloid β (Aβ) pathology is accumulating in the preclinical disease stage, glucocorticoid receptor signalling during stressful events exacerbates cellular dysfunction caused by Aβ. Alternatively, Aβ may disrupt glucocorticoid receptor signalling. To explore these possibilities, we investigated whether the synthetic glucocorticoid dexamethasone and Aβ have overlapping effects on the cellular proteome and whether Aβ influences canonical glucocorticoid receptor function. Human olfactory neurosphere-derived (ONS) cells, collected from the olfactory mucosa of six adult donors, were treated with soluble Aβ40 or Aβ42 followed by dexamethasone. Proteins were quantified by mass spectrometry. After 32 h treatment, Aβ40 and Aβ42 both induced profound changes in innate immunity-related proteins. After 72 h, Aβ42 formed widespread aggregates and induced few proteomic changes, whereas Aβ40 remained soluble and altered expression of mitochondrial and innate immunity-related proteins. ONS cells revealed overlapping impacts of Aβ40 and dexamethasone, with 23 proteins altered by both treatments. For 16 proteins (including eight mitochondrial proteins) dexamethasone counteracted the effects of Aβ40. For example, caspase 4 and methylmalonate-semialdehyde dehydrogenase were increased by Aβ40 and decreased by dexamethasone. Consistent with this finding, Aβ40 increased, but dexamethasone decreased, ONS cell proliferation. For seven proteins, including superoxide dismutase [Mn] mitochondrial, dexamethasone exacerbated the effects of Aβ40. For some proteins, including complement C3, the effects of dexamethasone differed depending on whether Aβ40 was present or absent. Neither Aβ species influenced glucocorticoid receptor nuclear translocation. Overall, this study revealed that glucocorticoid receptor signalling modifies the intracellular effects of Aß40, counteracting some effects and exacerbating others. It suggests that cellular mechanisms through which glucocorticoid receptor signalling influences Alzheimer's disease risk/progression are complex and determined by the balance of beneficial and detrimental glucocorticoid effects.

Beyond the Illusion of Controlled Environments: How to Embrace Ecological Pertinence in Research?

Through the lens of preclinical research on substance use disorders (SUD), I propose a reflection aimed at re-evaluating animal models in neuroscience, with a focus on ecological relevance. While rodent models have provided valuable insights into the neurobiology of SUD, the field currently faces a validation crisis, with findings often failing to translate into effective human treatments. Originally designed to address the lack of reproducibility in animal studies, the current global gold standard of rigorous standardization has led to increasingly controlled environments. This growing disconnection between laboratory settings and real-world scenarios exacerbates the validation crisis. Rodent models have also revealed various environmental influences on drug use and its neural mechanisms, highlighting parallels with human behaviour and underscoring the importance of ecological relevance in behavioural research. Drawing inspiration from inquiries in ethology and evolutionary biology, I advocate for incorporating greater environmental complexity into animal models. In line with this idea, the neuroethological approach involves studying spontaneous behaviours in seminatural habitats while utilizing advanced technologies to monitor neural activity. Although this framework offers new insights into human neuroscience, it does not adequately capture the complex human conditions that lead to neuropsychiatric diseases. Therefore, preclinical research should prioritize understanding the environmental factors that shape human behaviour and neural architecture, integrating these insights into animal models. By emphasizing ecological relevance, we can achieve deeper insights into neuropsychiatric disorders and develop more effective treatment strategies. This approach highlights significant benefits for both scientific inquiry and ethical considerations. The controlled environment is a chimera; it is time to rethink our models. Here, I have chosen the prism of preclinical research on SUD to present, in a nonexhaustive manner, advances enabled by the use of rodent models, the crises faced by animal experimentation, the reflections and responses provided by laboratories, to finally propose rethinking our models around questions of ecological relevance, in order to improve both ethics and scientific quality. Although my discussion is illustrated by the situation in preclinical research on SUD, the observation drawn from it and the proposals made can extend to many other domains and species.

Nebulized vasopressin penetrates CSF and improves social cognition without inducing aggression in a rhesus monkey model of autism

Low cerebrospinal (CSF) arginine vasopressin (AVP) concentration is a biomarker of social impairment in low-social monkeys and children with autism, suggesting that AVP administration may improve primate social functioning. However, AVP administration also increases aggression, at least in "neurotypical" animals with intact AVP signaling. Here, we tested the effects of a voluntary drug administration method in low-social male rhesus monkeys with high autistic-like trait burden. Monkeys received nebulized AVP or placebo, using a within-subjects design. Study 1 (N = 8) investigated the effects of AVP administration on social cognition in two tests comparing responses to social versus nonsocial stimuli. Test 1: Placebo-administered monkeys lacked face recognition memory, whereas face recognition memory was "rescued" following AVP administration. In contrast, object recognition memory was intact and did not differ between administration conditions. Test 2: Placebo-administered monkeys did not respond to conspecific social communication cues, whereas following AVP administration, they reciprocated affiliative communication cues with species-typical affiliative responses. Importantly, AVP administration did not increase aggressive responses to conspecific aggressive or affiliative overtures. Study 2 (N = 4) evaluated the pharmacokinetics of this administration method. Following AVP nebulization, we observed a linear increase in cisternal CSF AVP levels, and a quadratic rise and fall in blood AVP levels. These findings indicate that nebulized AVP likely penetrates the central nervous system, selectively promotes species-typical responses to social information, and does not induce aggression in low-social individuals. Nebulized AVP therefore may hold promise for managing similar social symptoms in people with autism, particularly in very young or lower functioning individuals.

Animal models in neuroscience with alternative approaches: Evolutionary, biomedical, and ethical perspectives

Animal models have been a crucial tool in neuroscience research for decades, providing insights into the biomedical and evolutionary mechanisms of the nervous system, disease, and behavior. However, their use has raised concerns on several ethical, clinical, and scientific considerations. The welfare of animals and the 3R principles (replacement, reduction, refinement) are the focus of the ethical concerns, targeting the importance of reducing the stress and suffering of these models. Several laws and guidelines are applied and developed to protect animal rights during experimenting. Concurrently, in the clinic and biomedical fields, discussions on the relevance of animal model findings on human organisms have increased. Latest data suggest that in a considerable amount of time the animal model results are not translatable in humans, costing time and money. Alternative methods, such as in vitro (cell culture, microscopy, organoids, and micro physiological systems) techniques and in silico (computational) modeling, have emerged as potential replacements for animal models, providing more accurate data in a minimized cost. By adopting alternative methods and promoting ethical considerations in research practices, we can achieve the 3R goals while upholding our responsibility to both humans and other animals. Our goal is to present a thorough review of animal models used in neuroscience from the biomedical, evolutionary, and ethical perspectives. The novelty of this research lies in integrating diverse points of views to provide an understanding of the advantages and disadvantages of animal models in neuroscience and in discussing potential alternative methods.

Recent advances and current status of gene therapy for epilepsy

BACKGROUND

Epilepsy is a common neurological disorder with complex pathogenic mechanisms, and refractory epilepsy often lacks effective treatments. Gene therapy is a promising therapeutic option, with various preclinical experiments achieving positive results, some of which have progressed to clinical studies.

DATA SOURCES

This narrative review was conducted by searching for papers published in PubMed/MEDLINE with the following single and/or combination keywords: epilepsy, children, neurodevelopmental disorders, genetics, gene therapy, vectors, transgenes, receptors, ion channels, micro RNAs (miRNAs), clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas)9 (CRISPR/Cas9), expression regulation, optogenetics, chemical genetics, mitochondrial epilepsy, challenges, ethics, and disease models.

RESULTS

Currently, gene therapy research in epilepsy primarily focuses on symptoms attenuation mediated by viral vectors such as adeno-associated virus and other types. Advances in gene therapy technologies, such as CRISPR/Cas9, have provided a new direction for epilepsy treatment. However, the clinical application still faces several challenges, including issues related to vectors, models, expression controllability, and ethical considerations.

CONCLUSIONS

Here, we summarize the relevant research and clinical advances in gene therapy for epilepsy and outline the challenges facing its clinical application. In addition to the shortcomings inherent in gene therapy components, the reconfiguration of excitatory and inhibitory properties in epilepsy treatment is a delicate process. On-demand, cell-autonomous treatments and multidisciplinary collaborations may be crucial in addressing these issues. Understanding gene therapy for epilepsy will help clinicians gain a clearer perception of the research progress and challenges, guiding the design of future clinical protocols and research decisions.

The cell-permeant antioxidant D-thiol ester D-cysteine ethyl ester overcomes physical dependence to morphine in male Sprague Dawley rats

The ability of morphine to decrease cysteine transport into neurons by inhibition of excitatory amino acid transporter 3 (EAA3) may be a key molecular mechanism underlying the acquisition of physical and psychological dependence to morphine. This study examined whether co-administration of the cell-penetrant antioxidant D-thiol ester, D-cysteine ethyl ester (D-CYSee), with morphine, would diminish the development of physical dependence to morphine in male Sprague Dawley rats. Systemic administration of the opioid receptor antagonist, naloxone (NLX), elicited pronounced withdrawal signs (e.g., wet-dog shakes, jumps, rears, circling) in rats that received a subcutaneous depot of morphine (150 mg/kg, SC) for 36 h and continuous intravenous infusion of vehicle (20 μL/h, IV). The NLX-precipitated withdrawal signs were reduced in rats that received an infusion of D-CYSee, but not D-cysteine, (both at 20.8 μmol/kg/h, IV) for the full 36 h. NLX elicited pronounced withdrawal signs in rats treated for 48 h with morphine (150 mg/kg, SC), plus continuous infusion of vehicle (20 μL/h, IV) that began at the 36 h timepoint of morphine treatment. The NLX-precipitated withdrawal signs were reduced in rats that received a 12 h infusion of D-CYSee, but not D-cysteine, (both at 20.8 μmol/kg/h, IV) that began at the 36 h timepoint of morphine treatment. These findings suggest that D-CYSee may attenuate the development of physical dependence to morphine and reverse established dependence to the opioid in male Sprague Dawley rats. Alternatively, D-CYSee may simply suppress the processes responsible for NLX-precipitated withdrawal. Nonetheless, D-CYSee and analogues may be novel therapeutics for the treatment of opioid use disorders.

Artificial Intelligence as a Replacement for Animal Experiments in Neurology: Potential, Progress, and Challenges

Animal experimentation has long been a cornerstone of neurology research, but it faces growing scientific, ethical, and economic challenges. Advances in artificial intelligence (AI) are providing new opportunities to replace animal testing with more human-relevant and efficient methods. This article explores the potential of AI technologies such as brain organoids, computational models, and machine learning to revolutionize neurology research and reduce reliance on animal models. These approaches can better recapitulate human brain physiology, predict drug responses, and uncover novel insights into neurological disorders. They also offer faster, cheaper, and more ethical alternatives to animal experiments. Case studies demonstrate AI's ability to accelerate drug discovery for Alzheimer's, predict neurotoxicity, personalize treatments for Parkinson's, and restore movement in paralysis. While challenges remain in validating and integrating these technologies, the scientific, economic, practical, and moral advantages are driving a paradigm shift towards AI-based, animal-free research in neurology. With continued investment and collaboration across sectors, AI promises to accelerate the development of safer and more effective therapies for neurological conditions while significantly reducing animal use. The path forward requires the ongoing development and validation of these technologies, but a future in which they largely replace animal experiments in neurology appears increasingly likely. This transition heralds a new era of more humane, human-relevant, and innovative brain research.

Prefrontal cortex neurons encode ambient light intensity differentially across regions and layers

While light can affect emotional and cognitive processes of the medial prefrontal cortex (mPFC), no light-encoding was hitherto identified in this region. Here, extracellular recordings in awake mice revealed that over half of studied mPFC neurons showed photosensitivity, that was diminished by inhibition of intrinsically photosensitive retinal ganglion cells (ipRGCs), or of the upstream thalamic perihabenular nucleus (PHb). In 15% of mPFC photosensitive neurons, firing rate changed monotonically along light-intensity steps and gradients. These light-intensity-encoding neurons comprised four types, two enhancing and two suppressing their firing rate with increased light intensity. Similar types were identified in the PHb, where they exhibited shorter latency and increased sensitivity. Light suppressed prelimbic activity but boosted infralimbic activity, mirroring the regions' contrasting roles in fear-conditioning, drug-seeking, and anxiety. We posit that prefrontal photosensitivity represents a substrate of light-susceptible, mPFC-mediated functions, which could be ultimately studied as a therapeutical target in psychiatric and addiction disorders.

Measuring the replicability of our own research

In the study of transgenic mouse models of neurodevelopmental and neurodegenerative disorders, we use batteries of tests to measure deficits in behaviour and from the results of these tests, we make inferences about the mental states of the mice that we interpret as deficits in "learning", "memory", "anxiety", "depression", etc. This paper discusses the problems of determining whether a particular transgenic mouse is a valid mouse model of disease X, the problem of background strains, and the question of whether our behavioural tests are measuring what we say they are. The problem of the reliability of results is then discussed: are they replicable between labs and can we replicate our results in our own lab? This involves the study of intra- and inter- experimenter reliability. The variables that influence replicability and the importance of conducting a complete behavioural phenotype: sensory, motor, cognitive and social emotional behaviour are discussed. Then the thorny question of failure to replicate is examined: Is it a curse or a blessing? Finally, the role of failure in research and what it tells us about our research paradigms is examined.

Lipophilic analogues of D-cysteine prevent and reverse physical dependence to fentanyl in male rats

We examined whether co-injections of the cell-permeant D-cysteine analogues, D-cysteine ethyl ester (D-CYSee) and D-cysteine ethyl amide (D-CYSea), prevent acquisition of physical dependence induced by twice-daily injections of fentanyl, and reverse acquired dependence to these injections in freely-moving male Sprague Dawley rats. Injection of the opioid receptor antagonist, naloxone HCl (NLX, 1.5 mg/kg, IV), elicited a series of withdrawal phenomena that included cardiorespiratory and behavioral responses, and falls in body weight and body temperature, in rats that received 5 or 10 injections of fentanyl (125 μg/kg, IV), and the same number of vehicle co-injections. Regarding the development of physical dependence, the NLX-precipitated withdrawal phenomena were markedly reduced in fentanyl-injected rats that had received co-injections of D-CYSee (250 μmol/kg, IV) or D-CYSea (100 μmol/kg, IV), but not D-cysteine (250 μmol/kg, IV). Regarding reversal of established dependence to fentanyl, the NLX-precipitated withdrawal phenomena in rats that had received 10 injections of fentanyl (125 μg/kg, IV) was markedly reduced in rats that received co-injections of D-CYSee (250 μmol/kg, IV) or D-CYSea (100 μmol/kg, IV), but not D-cysteine (250 μmol/kg, IV), starting with injection 6 of fentanyl. This study provides evidence that co-injections of D-CYSee and D-CYSea prevent the acquisition of physical dependence, and reverse acquired dependence to fentanyl in male rats. The lack of effect of D-cysteine suggests that the enhanced cell-penetrability of D-CYSee and D-CYSea into cells, particularly within the brain, is key to their ability to interact with intracellular signaling events involved in acquisition to physical dependence to fentanyl.

Genomic evidence for the suitability of Göttingen Minipigs with a rare seizure phenotype as a model for human epilepsy

Epilepsy is a complex genetic disorder that affects about 2% of the global population. Although the frequency and severity of epileptic seizures can be reduced by a range of pharmacological interventions, there are no disease-modifying treatments for epilepsy. The development of new and more effective drugs is hindered by a lack of suitable animal models. Available rodent models may not recapitulate all key aspects of the disease. Spontaneous epileptic convulsions were observed in few Göttingen Minipigs (GMPs), which may provide a valuable alternative animal model for the characterisation of epilepsy-type diseases and for testing new treatments. We have characterised affected GMPs at the genome level and have taken advantage of primary fibroblast cultures to validate the functional impact of fixed genetic variants on the transcriptome level. We found numerous genes connected to calcium metabolism that have not been associated with epilepsy before, such as ADORA2B, CAMK1D, ITPKB, MCOLN2, MYLK, NFATC3, PDGFD, and PHKB. Our results have identified two transcription factor genes, EGR3 and HOXB6, as potential key regulators of CACNA1H, which was previously linked to epilepsy-type disorders in humans. Our findings provide the first set of conclusive results to support the use of affected subsets of GMPs as an alternative and more reliable model system to study human epilepsy. Further neurological and pharmacological validation of the suitability of GMPs as an epilepsy model is therefore warranted.

Understanding Individual Subject Differences through Large Behavioral Datasets: Analytical and Statistical Considerations

A core feature of behavior analysis is the single-subject design, in which each subject serves as its own control. This approach is powerful for identifying manipulations that are causal to behavioral changes but often fails to account for individual differences, particularly when coupled with a small sample size. It is more common for other subfields of psychology to use larger-N approaches; however, these designs also often fail to account for the individual by focusing on aggregate-level data only. Moving forward, it is important to study individual differences to identify subgroups of the population that may respond differently to interventions and to improve the generalizability and reproducibility of behavioral science. We propose that large-N datasets should be used in behavior analysis to better understand individual subject variability. First, we describe how individual differences have been historically treated and then outline practical reasons to study individual subject variability. Then, we describe various methods for analyzing large-N datasets while accounting for the individual, including correlational analyses, machine learning, mixed-effects models, clustering, and simulation. We provide relevant examples of these techniques from published behavioral literature and from a publicly available dataset compiled from five different rat experiments, which illustrates both group-level effects and heterogeneity across individual subjects. We encourage other behavior analysts to make use of the substantial advancements in online data sharing to compile large-N datasets and use statistical approaches to explore individual differences.

L-cysteine ethyl ester prevents and reverses acquired physical dependence on morphine in male Sprague Dawley rats

The molecular mechanisms underlying the acquisition of addiction/dependence on morphine may result from the ability of the opioid to diminish the transport of L-cysteine into neurons via inhibition of excitatory amino acid transporter 3 (EAA3). The objective of this study was to determine whether the co-administration of the cell-penetrant L-thiol ester, L-cysteine ethyl ester (L-CYSee), would reduce physical dependence on morphine in male Sprague Dawley rats. Injection of the opioid-receptor antagonist, naloxone HCl (NLX; 1.5 mg/kg, IP), elicited pronounced withdrawal phenomena in rats which received a subcutaneous depot of morphine (150 mg/kg) for 36 h and were receiving a continuous infusion of saline (20 μL/h, IV) via osmotic minipumps for the same 36 h period. The withdrawal phenomena included wet-dog shakes, jumping, rearing, fore-paw licking, 360° circling, writhing, apneas, cardiovascular (pressor and tachycardia) responses, hypothermia, and body weight loss. NLX elicited substantially reduced withdrawal syndrome in rats that received an infusion of L-CYSee (20.8 μmol/kg/h, IV) for 36 h. NLX precipitated a marked withdrawal syndrome in rats that had received subcutaneous depots of morphine (150 mg/kg) for 48 h) and a co-infusion of vehicle. However, the NLX-precipitated withdrawal signs were markedly reduced in morphine (150 mg/kg for 48 h)-treated rats that began receiving an infusion of L-CYSee (20.8 μmol/kg/h, IV) at 36 h. In similar studies to those described previously, neither L-cysteine nor L-serine ethyl ester (both at 20.8 μmol/kg/h, IV) mimicked the effects of L-CYSee. This study demonstrates that 1) L-CYSee attenuates the development of physical dependence on morphine in male rats and 2) prior administration of L-CYSee reverses morphine dependence, most likely by intracellular actions within the brain. The lack of the effect of L-serine ethyl ester (oxygen atom instead of sulfur atom) strongly implicates thiol biochemistry in the efficacy of L-CYSee. Accordingly, L-CYSee and analogs may be a novel class of therapeutics that ameliorate the development of physical dependence on opioids in humans.

Toward a Precision Treatment Approach for Metabolic Depression: Integrating Epidemiology, Neuroscience, and Psychiatry

Background

Individuals with comorbid major depressive disorder and type 2 diabetes represent an important subgroup of patients for whom conventional treatment may be insufficient. A precision treatment approach that addresses insulin resistance with an outcome of a positive response to antidepressants may prove beneficial.

Methods

This study utilized an emulated target trial on a large dataset from the Optum Clinformatics Data Mart Database. We evaluated the effect of adjuvant pioglitazone, an insulin-sensitizing drug, on antidepressant response among 4696 people with type 2 diabetes, comparing it with DPP4 (dipeptidyl peptidase-4) inhibitors (non-insulin-sensitizing). An additional analysis involving 6518 participants was conducted to assess the efficacy of pioglitazone versus sulfonylureas.

Results

The instrumental variable analysis indicated that the initiation of an antidepressant with pioglitazone was superior to DPP4 inhibitors in terms of antidepressant response, with fewer treatment shifts and/or additions of new antidepressant or antipsychotic over a 1-year period. This result was consistent when pioglitazone was compared with sulfonylureas in a supplemental analysis.

Conclusions

Our findings suggest that pioglitazone may be more effective than DPP4 inhibitors or sulfonylureas in enhancing antidepressant response among people with comorbid major depressive disorder and type 2 diabetes. This provides a strong case for the use of pioglitazone in patients with these conditions, emphasizing the potential of precision medicine strategies. The results should be interpreted with caution due to inherent limitations associated with observational data.

Statistical power and false positive rates for interdependent outcomes are strongly influenced by test type: Implications for behavioral neuroscience

Statistical errors in preclinical science are a barrier to reproducibility and translation. For instance, linear models (e.g., ANOVA, linear regression) may be misapplied to data that violate assumptions. In behavioral neuroscience and psychopharmacology, linear models are frequently applied to interdependent or compositional data, which includes behavioral assessments where animals concurrently choose between chambers, objects, outcomes, or types of behavior (e.g., forced swim, novel object, place/social preference). The current study simulated behavioral data for a task with four interdependent choices (i.e., increased choice of a given outcome decreases others) using Monte Carlo methods. 16,000 datasets were simulated (1000 each of 4 effect sizes by 4 sample sizes) and statistical approaches evaluated for accuracy. Linear regression and linear mixed effects regression (LMER) with a single random intercept resulted in high false positives (>60%). Elevated false positives were attenuated in an LMER with random effects for all choice-levels and a binomial logistic mixed effects regression. However, these models were underpowered to reliably detect effects at common preclinical sample sizes. A Bayesian method using prior knowledge for control subjects increased power by up to 30%. These results were confirmed in a second simulation (8000 datasets). These data suggest that statistical analyses may often be misapplied in preclinical paradigms, with common linear methods increasing false positives, but potential alternatives lacking power. Ultimately, using informed priors may balance statistical requirements with ethical imperatives to minimize the number of animals used. These findings highlight the importance of considering statistical assumptions and limitations when designing research studies.

Time to consider animal data governance: perspectives from neuroscience

Introduction

Scientific research relies mainly on multimodal, multidimensional big data generated from both animal and human organisms as well as technical data. However, unlike human data that is increasingly regulated at national, regional and international levels, regulatory frameworks that can govern the sharing and reuse of non-human animal data are yet to be established. Whereas the legal and ethical principles that shape animal data generation in many countries and regions differ, the generated data are shared beyond boundaries without any governance mechanism. This paper, through perspectives from neuroscience, shows conceptually and empirically that there is a need for animal data governance that is informed by ethical concerns. There is a plurality of ethical views on the use of animals in scientific research that data governance mechanisms need to consider.

Methods

Semi-structured interviews were used for data collection. Overall, 13 interviews with 12 participants (10 males and 2 females) were conducted. The interviews were transcribed and stored in NviVo 12 where they were thematically analyzed.

Results

The participants shared the view that it is time to consider animal data governance due to factors such as differences in regulations, differences in ethical principles, values and beliefs and data quality concerns. They also provided insights on possible approaches to governance.

Discussion

We therefore conclude that a procedural approach to data governance is needed: an approach that does not prescribe a particular ethical position but allows for a quick understanding of ethical concerns and debate about how different positions differ to facilitate cross-cultural and international collaboration.

Diversity and inclusion for rodents: how animal ethics committees can help improve translation

Translation failure occurs when a treatment shown to be safe and effective in one type of population does not produce the same result in another. We are currently in a crisis involving the translatability of preclinical studies to human populations. Animal trials are no better than a coin toss at predicting the safety and efficacy of drugs in human trials, and the high failure rate of drugs entering human trials suggests that most of the suffering of laboratory animals is futile, creating no commensurate benefit for human patients. Here, I argue that animal ethics committees have a role to play in getting us out of this crisis. Inadequate representation is a known contributor to translation failures and is a matter of both scientific and ethical concern. Ethical review committees have the authority to address it by reprioritising the values already enshrined in their guiding principles.

Individualized Housing Modifies the Immune–Endocrine System in CD1 Adult Male Mice

In the last years, different research groups have made considerable efforts to improve the care and use of animals in research. Mice (Mus musculus) are the most widely used animal species in research in the European Union and are sociable and hierarchical creatures. During experiments, researchers tend to individualize males, but no consideration is given to whether this social isolation causes them stress. The aim of this study was, therefore, to explore whether 4 weeks of social isolation could induce changes in different physiological parameters in adult Crl:CD1(ICR) (CD1) males, which may interfere with experimental results. Body weight, blood cells, and fecal corticosterone metabolites levels were the analyzed parameters. Blood and fecal samples were collected at weeks 1 and 4 of the experimental procedure. Four weeks of single housing produced a significant time-dependent decrease in monocytes and granulocytes. Fecal corticosterone metabolite levels were higher in single-housed mice after 1 week and then normalized after 4 weeks of isolation. Body weight, red blood cells, and platelets remained unchanged in both groups during this period. We can, therefore, conclude that social isolation affects some immune and endocrine parameters, and that this should be taken into account in the interpretation of research data.

A paradigm shift in translational psychiatry through rodent neuroethology

Mental disorders are a significant cause of disability worldwide. They profoundly affect individuals' well-being and impose a substantial financial burden on societies and governments. However, despite decades of extensive research, the effectiveness of current therapeutics for mental disorders is often not satisfactory or well tolerated by the patient. Moreover, most novel therapeutic candidates fail in clinical testing during the most expensive phases (II and III), which results in the withdrawal of pharma companies from investing in the field. It also brings into question the effectiveness of using animal models in preclinical studies to discover new therapeutic agents and predict their potential for treating mental illnesses in humans. Here, we focus on rodents as animal models and propose that they are essential for preclinical investigations of candidate therapeutic agents' mechanisms of action and for testing their safety and efficiency. Nevertheless, we argue that there is a need for a paradigm shift in the methodologies used to measure animal behavior in laboratory settings. Specifically, behavioral readouts obtained from short, highly controlled tests in impoverished environments and social contexts as proxies for complex human behavioral disorders might be of limited face validity. Conversely, animal models that are monitored in more naturalistic environments over long periods display complex and ethologically relevant behaviors that reflect evolutionarily conserved endophenotypes of translational value. We present how semi-natural setups in which groups of mice are individually tagged, and video recorded continuously can be attainable and affordable. Moreover, novel open-source machine-learning techniques for pose estimation enable continuous and automatic tracking of individual body parts in groups of rodents over long periods. The trajectories of each individual animal can further be subjected to supervised machine learning algorithms for automatic detection of specific behaviors (e.g., chasing, biting, or fleeing) or unsupervised automatic detection of behavioral motifs (e.g., stereotypical movements that might be harder to name or label manually). Compared to studies of animals in the wild, semi-natural environments are more compatible with neural and genetic manipulation techniques. As such, they can be used to study the neurobiological mechanisms underlying naturalistic behavior. Hence, we suggest that such a paradigm possesses the best out of classical ethology and the reductive behaviorist approach and may provide a breakthrough in discovering new efficient therapies for mental illnesses.

Wild brains: The value of neuroethological approaches in preclinical behavioral neuroscience animal models

For three decades, IBNS has provided a forum for the dissemination of behavioral neuroscience research, broadly defined. Throughout this time, research presented at the annual meetings has reflected representative trends in the field with an emphasis on relevant preclinical animal models. From its inception, IBNS has contributed to my professional development and evolving research interests. Unsurprisingly, throughout the three decades of its existence, IBNS annual programs have reflected research trends that have been thoughtfully evaluated, challenged, and, in some cases, recalibrated. An emphasis in my lab, for example, has slowly navigated toward the inclusion of more diverse species (e.g., nonhuman primate models, wild rats, wild and captive raccoons) assessed in settings that reflect more ethological relevance than typically observed in traditional laboratory settings. Consequently, my research interests are pivoting from laboratory animal model exclusive (L.A.M.E.) endeavors to more natural, diverse, ethoexperimental approaches. As progress toward translational findings for psychiatric and neurological conditions is considered, it is recommended that researchers remain open to nontraditional methodological approaches that incorporate diverse animal models and assessments to inform laboratory-generated findings.

Small sensory spinal lesions that affect hand function in monkeys greatly alter primary afferent and motor neuron connections in the cord

Small sensory spinal injuries induce plasticity across the neuraxis, but little is understood about their effect on segmental connections or motor neuron (MN) function. Here, we begin to address this at two levels. First, we compared afferent input distributions from the skin and muscles of the digits with corresponding MN pools to determine their spatial relationship, in both the normal state and 4-6 months after a unilateral dorsal root/dorsal column lesion (DRL/DCL), affecting digits 1-3. Second, we looked at specific changes to MN inputs and membrane properties that likely impact functional recovery. Monkeys received a targeted unilateral DRL/DCL, and 4-6 months later, cholera toxin subunit B (CT-B) was injected bilaterally into either the distal pads of digits 1-3, or related intrinsic hand muscles, to label inputs to the cord, and corresponding MNs. In controls (unlesioned side), cutaneous and proprioceptive afferents from digits 1-3 showed different distribution patterns but similar rostrocaudal spread within the dorsal horn from C1 to T2. In contrast, MNs were distributed across just two segments (C7-8). Following the lesion, sensory inputs were significantly diminished across all 10 segments, though this did not alter MN distributions. Afferent and monoamine inputs, as well as KCC2 cotransporters, were also significantly altered on the cell membrane of CT-B labeled MNs postlesion. In contrast, inhibitory neurotransmission and perineuronal net integrity were not altered at this prechronic timepoint.  Our findings indicate that even a small sensory injury can significantly impact sensory and motor spinal neurons and provide new insight into the complex process of recovery.

A human-derived neurovascular unit in vitro model to study the effects of cellular cross-talk and soluble factors on barrier integrity

The blood-brain barrier (BBB) restricts paracellular and transcellular diffusion of compounds and is part of a dynamic multicellular structure known as the "neurovascular unit" (NVU), which strictly regulates the brain homeostasis and microenvironment. Several neuropathological conditions (e.g., Parkinson's disease and Alzheimer's disease), are associated with BBB impairment yet the exact underlying pathophysiological mechanisms remain unclear. In total, 90% of drugs that pass animal testing fail human clinical trials, in part due to inter-species discrepancies. Thus, in vitro human-based models of the NVU are essential to better understand BBB mechanisms; connecting its dysfunction to neuropathological conditions for more effective and improved therapeutic treatments. Herein, we developed a biomimetic tri-culture NVU in vitro model consisting of 3 human-derived cell lines: human cerebral micro-vascular endothelial cells (hCMEC/D3), human 1321N1 (astrocyte) cells, and human SH-SY5Y neuroblastoma cells. The cells were grown in Transwell hanging inserts in a variety of configurations and the optimal setup was found to be the comprehensive tri-culture model, where endothelial cells express typical markers of the BBB and contribute to enhancing neural cell viability and neurite outgrowth. The tri-culture configuration was found to exhibit the highest transendothelial electrical resistance (TEER), suggesting that the cross-talk between astrocytes and neurons provides an important contribution to barrier integrity. Lastly, the model was validated upon exposure to several soluble factors [e.g., Lipopolysaccharides (LPS), sodium butyrate (NaB), and retinoic acid (RA)] known to affect BBB permeability and integrity. This in vitro biological model can be considered as a highly biomimetic recapitulation of the human NVU aiming to unravel brain pathophysiology mechanisms as well as improve testing and delivery of therapeutics.

Bridging the Gap: Human Emotions and Animal Emotions

Our experiences of the conscious mental states that we call emotions drive our interest in whether such states also exist in other animals. Because linguistic report can be used as a gold standard (albeit indirect) indicator of subjective emotional feelings in humans but not other species, how can we investigate animal emotions and what exactly do we mean when we use this term? Linguistic reports of human emotion give rise to emotion concepts (discrete emotions; dimensional models), associated objectively measurable behavioral and bodily emotion indicators, and understanding of the emotion contexts that generate specific states. We argue that many animal studies implicitly translate human emotion concepts, indicators and contexts, but that explicit consideration of the underlying pathways of inference, their theoretical basis, assumptions, and pitfalls, and how they relate to conscious emotional feelings, is needed to provide greater clarity and less confusion in the conceptualization and scientific study of animal emotion.

Threats to Benefits: Assessing Knowledge Production in Nonhuman Models of Human Neuropsychiatric Disorders

Recent reports and papers on chimeric research highlight the promise of chimeric models of human neuropsychiatric disorders to ameliorate human suffering due to autism spectrum disorders, depression, and schizophrenia. These calls, however, typically do not acknowledge, much less address, criticisms of model creation and validation, or concerns about scientific conduct more generally. The ethical justification for the use of nonhuman animals in research depends on the production of benefits to humans based on such research. But the assessment and production of benefits are highly uncertain and rife with both practical and conceptual challenges. This essay provides a general framework for classifying the benefits of biomedical research and then focuses on two factors that directly impact-and threaten-the production of knowledge in research that models neuropsychiatric disorders.

Tips and traps for behavioural animal experimentation

Behavioural animal experimentation is an inseparable part of research trying to understand the biological underpinnings of human behaviour, diseases and disorders. Working with animals comes with great responsibility to achieve reliable and reproducible results of highest scientific quality. In a simple step-by-step fashion, we highlight some common issues that may occur along the path to conducting behavioural animal experimentations and posit some solutions and grounds to ensure the excellence of work done in this research area while aspiring to improve conditions for laboratory animals. It entails topics of study design, animal and experimenter welfare, experimental considerations and frequentist biostatistics. At the end, we direct to some guidelines and manuals that may prove valuable to researchers in this field. Our ten simple tips and traps are meant for students who are learning about important concepts for the first time; graduates whose statistics training all too often has neglected the concept of power in experimental design; and researches who would like a light-hearted refresher on these topics. With this perspective, we hope that you will avoid falling into traps and find answers to what you always wanted to know about conducting behavioural animal experimentation.

Introduction of a pharmacological neurovascular uncoupling model in rats based on results of mice

Our aim was to establish a pharmacologically induced neurovascular uncoupling (NVU) method in rats as a model of human cognitive decline. Pharmacologically induced NVU with subsequent neurological and cognitive defects was described in mice, but not in rats so far. We used 32 male Hannover Wistar rats. NVU was induced by intraperitoneal administration of a pharmacological "cocktail" consisting of N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MSPPOH, a specific inhibitor of epoxyeicosatrienoic acid-producing epoxidases, 5 mg kg-1), L-NG-nitroarginine methyl ester (L-NAME, a nitric oxide synthase inhibitor, 10 mg kg-1) and indomethacin (a nonselective inhibitor of cyclooxygenases, 1 mg kg-1) and injected twice daily for 8 consecutive days. Cognitive performance was tested in the Morris water-maze and fear-conditioning assays. We also monitored blood pressure. In a terminal operation a laser Doppler probe was used to detect changes in blood-flow (CBF) in the barrel cortex while the contralateral whisker pad was stimulated. Brain and small intestine tissue samples were collected post mortem and examined for prostaglandin E2 (PGE2) level. Animals treated with the "cocktail" showed no impairment in their performance in any of the cognitive tasks. They had higher blood pressure and showed cca. 50% decrease in CBF. Intestinal bleeding and ulcers were found in some animals with significantly decreased levels of PGE2 in the brain and small intestine. Although we could evoke NVU by the applied mixture of pharmacons, it also induced adverse side effects such as hypertension and intestinal malformations while the treatment did not cause cognitive impairment. Thus, further refinements are still required for the development of an applicable model.

An Optimized Comparative Proteomic Approach as a Tool in Neurodegenerative Disease Research

Recent advances in proteomic technologies now allow unparalleled assessment of the molecular composition of a wide range of sample types. However, the application of such technologies and techniques should not be undertaken lightly. Here, we describe why the design of a proteomics experiment itself is only the first step in yielding high-quality, translatable results. Indeed, the effectiveness and/or impact of the majority of contemporary proteomics screens are hindered not by commonly considered technical limitations such as low proteome coverage but rather by insufficient analyses. Proteomic experimentation requires a careful methodological selection to account for variables from sample collection, through to database searches for peptide identification to standardised post-mass spectrometry options directed analysis workflow, which should be adjusted for each study, from determining when and how to filter proteomic data to choosing holistic versus trend-wise analyses for biologically relevant patterns. Finally, we highlight and discuss the difficulties inherent in the modelling and study of the majority of progressive neurodegenerative conditions. We provide evidence (in the context of neurodegenerative research) for the benefit of undertaking a comparative approach through the application of the above considerations in the alignment of publicly available pre-existing data sets to identify potential novel regulators of neuronal stability.

Mice in translational neuroscience: What R we doing?

Animal models play a pivotal role in translational neuroscience but recurrent problems in data collection, analyses, and interpretation, lack of biomarkers, and a tendency to over-reliance on mice have marred neuroscience progress, leading to one of the highest attrition rates in drug translation. Global initiatives to improve reproducibility and model selection are being implemented. Notwithstanding, mice are still the preferred animal species to model human brain disorders even when the translation has been shown to be limited. Non-human primates are better positioned to provide relevant translational information because of their higher brain complexity and homology to humans. Among others, lack of resources and formal training, strict legislation, and ethical issues may impede broad access to large animals. We propose that instead of increasingly restrictive legislation, more resources for training, education, husbandry, and data sharing are urgently needed. The creation of multidisciplinary teams, in which veterinarians need to play a key role, would be critical to improve translational efficiency. Furthermore, it is not usually acknowledged by researchers and regulators the value of comparative studies in lower species, that are instrumental in toxicology, target identification, and mechanistic studies. Overall, we highlight here the need for a conceptual shift in neuroscience research and policies to reach the patients.

Questionable Research Practices, Low Statistical Power, and Other Obstacles to Replicability: Why Preclinical Neuroscience Research Would Benefit from Registered Reports

Replicability, the degree to which a previous scientific finding can be repeated in a distinct set of data, has been considered an integral component of institutionalized scientific practice since its inception several hundred years ago. In the past decade, large-scale replication studies have demonstrated that replicability is far from favorable, across multiple scientific fields. Here, I evaluate this literature and describe contributing factors including the prevalence of questionable research practices (QRPs), misunderstanding of p-values, and low statistical power. I subsequently discuss how these issues manifest specifically in preclinical neuroscience research. I conclude that these problems are multifaceted and difficult to solve, relying on the actions of early and late career researchers, funding sources, academic publishers, and others. I assert that any viable solution to the problem of substandard replicability must include changing academic incentives, with adoption of registered reports being the most immediately impactful and pragmatic strategy. For animal research in particular, comprehensive reporting guidelines that document potential sources of sensitivity for experimental outcomes is an essential addition.

Leveraging a translational research approach to drive diagnostic and treatment advances for autism

Autism spectrum disorder (ASD) is a prevalent and poorly understood neurodevelopmental disorder. There are currently no laboratory-based diagnostic tests to detect ASD, nor are there any disease-modifying medications that effectively treat ASD's core behavioral symptoms. Scientific progress has been impeded, in part, by overreliance on model organisms that fundamentally lack the sophisticated social and cognitive abilities essential for modeling ASD. We therefore saw significant value in studying naturally low-social rhesus monkeys to model human social impairment, taking advantage of a large outdoor-housed colony for behavioral screening and biomarker identification. Careful development and validation of our animal model, combined with a strong commitment to evaluating the translational utility of our preclinical findings directly in patients with ASD, yielded a robust neurochemical marker (cerebrospinal fluid vasopressin concentration) of trans-primate social impairment and a first-in-class medication (intranasal vasopressin) shown in a small phase 2a pilot trial to improve social abilities in children with ASD. This translational research approach stands to advance our understanding of ASD in a manner not readily achievable with existing animal models, and can be adapted to investigate a variety of other human brain disorders which currently lack valid preclinical options, thereby streamlining translation and amplifying clinical impact more broadly.

Home cage measures of Alzheimer's disease in the rTg4510 mouse model

Alzheimer's disease affects an array of activities in patients' daily lives but measures other than memory are rarely evaluated in animal models. Home cage behavior, however, may provide an opportunity to back translate a variety of measures seen in human disease progression to animal models, providing external and face validity. The aim of this study was to evaluate if home cage measures could indicate disease in the rTg4510 mouse model. We hypothesized that sleep, nesting, and smell discrimination would be altered in mutant mice. Thirty-two transgenic mice were used in a Latin square design of four genotypes x both sexes x two diets. Half the mice received a doxycycline diet to suppress tauopathy and evaluate tau severity on various measures. At 8-, 12-, and 16-weeks old, 24 h activity/sleep patterns, nest complexity, and odor discrimination were measured. After 16-weeks, tau concentration in the brain was quantified. Mutant mice had increased tau concentration in brain tissue, but it was reduced by the doxycycline diet. However, only nest complexity was different between mutant mice and controls. Overall, tauopathy in rTg4510 mice does seem to affect these commonly observed symptoms in human patients. However, while running this study, a report showed that the rTg4510 mutant phenotype is not caused by the mutation itself, but confounding factors from transgene insertion. Combined with report findings and our data, the rTg4510 model may not be an ideal model for all aspects of human Alzheimer's disease.

Engaging endogenous opioid circuits in pain affective processes

The pervasive use of opioid compounds for pain relief is rooted in their utility as one of the most effective therapeutic strategies for providing analgesia. While the detrimental side effects of these compounds have significantly contributed to the current opioid epidemic, opioids still provide millions of patients with reprieve from the relentless and agonizing experience of pain. The human experience of pain has long recognized the perceived unpleasantness entangled with a unique sensation that is immediate and identifiable from the first-person subjective vantage point as "painful." From this phenomenological perspective, how is it that opioids interfere with pain perception? Evidence from human lesion, neuroimaging, and preclinical functional neuroanatomy approaches is sculpting the view that opioids predominately alleviate the affective or inferential appraisal of nociceptive neural information. Thus, opioids weaken pain-associated unpleasantness rather than modulate perceived sensory qualities. Here, we discuss the historical theories of pain to demonstrate how modern neuroscience is revisiting these ideas to deconstruct the brain mechanisms driving the emergence of aversive pain perceptions. We further detail how targeting opioidergic signaling within affective or emotional brain circuits remains a strong avenue for developing targeted pharmacological and gene-therapy analgesic treatments that might reduce the dependence on current clinical opioid options.

Utilizing preclinical models of genetic diversity to improve translation of phytochemical activities from rodents to humans and inform personalized nutrition

Mouse models are an essential tool in different areas of research, including nutrition and phytochemical research. Traditional inbred mouse models have allowed the discovery of therapeutical targets and mechanisms of action and expanded our knowledge of health and disease. However, these models lack the genetic variability typically found in human populations, which hinders the translatability of the results found in mice to humans. The development of genetically diverse mouse models, such as the collaborative cross (CC) or the diversity outbred (DO) models, has been a useful tool to overcome this obstacle in many fields, such as cancer, immunology and toxicology. However, these tools have not yet been widely adopted in the field of phytochemical research. As demonstrated in other disciplines, use of CC and DO models has the potential to provide invaluable insights for translation of phytochemicals from rodents to humans, which are desperately needed given the challenges and numerous failed clinical trials in this field. These models may prove informative for personalized use of phytochemicals in humans, including: predicting interindividual variability in phytochemical bioavailability and efficacy, identifying genetic loci or genes governing response to phytochemicals, identifying phytochemical mechanisms of action and therapeutic targets, and understanding the impact of genetic variability on individual response to phytochemicals. Such insights would prove invaluable for personalized implementation of phytochemicals in humans. This review will focus on the current work performed with genetically diverse mouse populations, and the research opportunities and advantages that these models can offer to phytochemical research.

The impact of social variables in preclinical models of cocaine abuse

At present, there are no US Food and Drug Administration–approved treatments for cocaine use disorders. One consideration for this lack of treatment efficacy stems from the appropriate use of animal models. The premise of this commentary is that social behavior needs to be incorporated in animal models of cocaine use disorder. The goal of this commentary is to describe some of the strengths and limitations of recent preclinical animal models of cocaine abuse which have incorporated social behavior. There are many ways to include social variables into preclinical research, and the study design will depend on the questions asked. Four general types of studies incorporating social factors are described: those involving aggression (that is, maternal neglect and social defeat), modeling, social reward, and social housing, including social isolation. The inclusion of social variables into preclinical research will help identify biobehavioral markers that may lead to an individualized treatment approach that more effectively decreases cocaine use. These studies will aid in the development of novel pharmacotherapies as well as non-pharmacological interventions (for example, punishment, alternative reinforcers, and environmental enrichment) that would be critical for informing policy decisions.

Completing the puzzle: Why studies in non-human primates are needed to better understand the effects of non-invasive brain stimulation

Brain stimulation is a core method in neuroscience. Numerous non-invasive brain stimulation (NIBS) techniques are currently in use in basic and clinical research, and recent advances promise the ability to non-invasively access deep brain structures. While encouraging, there is a surprising gap in our understanding of precisely how NIBS perturbs neural activity throughout an interconnected network, and how such perturbed neural activity ultimately links to behaviour. In this review, we will consider why non-human primate (NHP) models of NIBS are ideally situated to address this gap in knowledge, and why the oculomotor network that moves our line of sight offers a particularly valuable platform in which to empirically test hypothesis regarding NIBS-induced changes in brain and behaviour. NHP models of NIBS will enable investigation of the complex, dynamic effects of brain stimulation across multiple hierarchically interconnected brain areas, networks, and effectors. By establishing such links between brain and behavioural output, work in NHPs can help optimize experimental and therapeutic approaches, improve NIBS efficacy, and reduce side-effects of NIBS.

Modelling behaviors relevant to brain disorders in the nonhuman primate: Are we there yet?

Recent years have seen a profound resurgence of activity with nonhuman primates (NHPs) to model human brain disorders. From marmosets to macaques, the study of NHP species offers a unique window into the function of primate-specific neural circuits that are impossible to examine in other models. Examining how these circuits manifest into the complex behaviors of primates, such as advanced cognitive and social functions, has provided enormous insights to date into the mechanisms underlying symptoms of numerous neurological and neuropsychiatric illnesses. With the recent optimization of modern techniques to manipulate and measure neural activity in vivo, such as optogenetics and calcium imaging, NHP research is more well-equipped than ever to probe the neural mechanisms underlying pathological behavior. However, methods for behavioral experimentation and analysis in NHPs have noticeably failed to keep pace with these advances. As behavior ultimately lies at the junction between preclinical findings and its translation to clinical outcomes for brain disorders, approaches to improve the integrity, reproducibility, and translatability of behavioral experiments in NHPs requires critical evaluation. In this review, we provide a unifying account of existing brain disorder models using NHPs, and provide insights into the present and emerging contributions of behavioral studies to the field.

Opiates Possibly Boosted Human Civilization

: Testosterone is a fundamental biological drive for human survival. Evidence documents an association between the evolutionary suppression of testosterone and the civilization processes, especially their socialization and family colonization abilities, among early humans. Interestingly, opiates suppress testosterone as a side effect. However, in clinical practice, clients undergoing opioid substitution therapy have subnormal, normal, or even above-normal testosterone. This paper discusses a possibility indicating that opiates promoted civilization processes among early humans. We further suggest that modern humans might have inherited the positive impact of opiates on early humans as a biological propensity for using opioids. Some users may use opioids for self-medication to decrease their extraordinarily high testosterone levels.

A review of systems biology research of anxiety disorders

The development of "omic" technologies and deep phenotyping may facilitate a systems biology approach to understanding anxiety disorders. Systems biology approaches incorporate data from multiple modalities (e.g., genomic, neuroimaging) with functional analyses (e.g., animal and tissue culture models) and mathematical modeling (e.g., machine learning) to investigate pathological biophysical networks at various scales. Here we review: i) the neurobiology of anxiety disorders; ii) how systems biology approaches have advanced this work; and iii) the clinical implications and future directions of this research. Systems biology approaches have provided an improved functional understanding of candidate biomarkers and have suggested future potential for refining the diagnosis, prognosis, and treatment of anxiety disorders. The systems biology approach for anxiety disorders is, however, in its infancy and in some instances is characterized by insufficient power and replication. The studies reviewed here represent important steps to further untangling the pathophysiology of anxiety disorders.

Neuroethics and Animals: Report and Recommendations From the University of Pennsylvania Animal Research Neuroethics Workshop

Growing awareness of the ethical implications of neuroscience in the early years of the 21st century led to the emergence of the new academic field of “neuroethics,” which studies the ethical implications of developments in the neurosciences. However, despite the acceleration and evolution of neuroscience research on nonhuman animals, the unique ethical issues connected with neuroscience research involving nonhuman animals remain underdiscussed. This is a significant oversight given the central place of animal models in neuroscience. To respond to these concerns, the Center for Neuroscience and Society and the Center for the Interaction of Animals and Society at the University of Pennsylvania hosted a workshop on the “Neuroethics of Animal Research” in Philadelphia, Pennsylvania. At the workshop, expert speakers and attendees discussed ethical issues arising from neuroscience research involving nonhuman animals, including the use of animal models in the study of pain and psychiatric conditions, animal brain-machine interfaces, animal–animal chimeras, cerebral organoids, and the relevance of neuroscience to debates about personhood. This paper highlights important emerging ethical issues based on the discussions at the workshop. This paper includes recommendations for research in the United States from the authors based on the discussions at the workshop, loosely following the format of the 2 Gray Matters reports on neuroethics published by the Presidential Commission for the Study of Bioethical Issues.