Cognition and Memory after Covid-19 in a Large Community Sample.

BACKGROUND: Cognitive symptoms after coronavirus disease 2019 (Covid-19), the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are well-recognized. Whether objectively measurable cognitive deficits exist and how long they persist are unclear. METHODS: We invited 800,000 adults in a study in England to complete an online assessment of cognitive function. We estimated a global cognitive score across eight tasks. We hypothesized that participants with persistent symptoms (lasting ≥12 weeks) after infection onset would have objectively measurable global cognitive deficits and that impairments in executive functioning and memory would be observed in such participants, especially in those who reported recent poor memory or difficulty thinking or concentrating ("brain fog"). RESULTS: Of the 141,583 participants who started the online cognitive assessment, 112,964 completed it. In a multiple regression analysis, participants who had recovered from Covid-19 in whom symptoms had resolved in less than 4 weeks or at least 12 weeks had similar small deficits in global cognition as compared with those in the no-Covid-19 group, who had not been infected with SARS-CoV-2 or had unconfirmed infection (-0.23 SD [95% confidence interval {CI}, -0.33 to -0.13] and -0.24 SD [95% CI, -0.36 to -0.12], respectively); larger deficits as compared with the no-Covid-19 group were seen in participants with unresolved persistent symptoms (-0.42 SD; 95% CI, -0.53 to -0.31). Larger deficits were seen in participants who had SARS-CoV-2 infection during periods in which the original virus or the B.1.1.7 variant was predominant than in those infected with later variants (e.g., -0.17 SD for the B.1.1.7 variant vs. the B.1.1.529 variant; 95% CI, -0.20 to -0.13) and in participants who had been hospitalized than in those who had not been hospitalized (e.g., intensive care unit admission, -0.35 SD; 95% CI, -0.49 to -0.20). Results of the analyses were similar to those of propensity-score-matching analyses. In a comparison of the group that had unresolved persistent symptoms with the no-Covid-19 group, memory, reasoning, and executive function tasks were associated with the largest deficits (-0.33 to -0.20 SD); these tasks correlated weakly with recent symptoms, including poor memory and brain fog. No adverse events were reported. CONCLUSIONS: Participants with resolved persistent symptoms after Covid-19 had objectively measured cognitive function similar to that in participants with shorter-duration symptoms, although short-duration Covid-19 was still associated with small cognitive deficits after recovery. Longer-term persistence of cognitive deficits and any clinical implications remain uncertain. (Funded by the National Institute for Health and Care Research and others.).

Conceptualising compulsivity through network analysis: A two-sample study.

Compulsivity is a transdiagnostic construct crucial to understanding multiple psychiatric conditions and problematic repetitive behaviours. Despite being identified as a clinical- and research-relevant construct, there are limited insights into the internal conceptual structure of compulsivity. To provide a more nuanced understanding of compulsivity, the current study estimated the structure of compulsivity (indexed using the previously validated Cambridge-Chicago Compulsivity Trait Scale, CHI-T) among two large-scale and geographically distinct samples using the network estimation method. The samples consisted of a United Kingdom cohort (n = 122,346, 51.4% female, Mean age = 43.7, SD = 16.5, range = 9-86 years) and a South Africa cohort (n = 2674, 65.6% female, Mean age = 24.6, SD = 8.6, range = 18-65 years). Network community analysis demonstrated that compulsivity was constituted of three interrelated dimensions, namely: perfectionism, cognitive rigidity and reward drive. Further, 'Completion leads to soothing' and 'Difficulty moving from task to task' were identified as core (central nodes) to compulsivity. The dimensional structure and central nodes of compulsivity networks were consistent across the two samples. These findings facilitate the conceptualisation and measurement of compulsivity and may contribute to the early detection and treatment of compulsivity-related disorders.

Anesthetic and analgesic techniques used for cats undergoing ovariohysterectomies in general practice in the United States.

OBJECTIVE: To better document anesthetic and analgesic protocols used by veterinarians in general practice within the United States (US) when performing elective ovariohysterectomy in cats. STUDY DESIGN: Cross-sectional survey. POPULATION: Veterinary practitioners in the US who are members of the Veterinary Information Network Inc. (VIN). METHODS: An online anonymous survey was distributed to VIN members. The survey included questions pertaining to preanesthetic evaluation, premedication, induction, monitoring and maintenance protocols, and postoperative analgesia and sedation protocols when performing ovariohysterectomy in cats. RESULTS: A total of 1324 veterinarians completed the survey. Respondents (number; %) reported performing preanesthetic laboratory tests [packed cell volume (256; 19.3%), complete blood cell count (893; 67.4%) and biochemistry panels (1101; 83.2%)] and preanesthetic examinations (1186; 89.6%) on the morning of surgery. The most frequently administered drugs for premedication were dexmedetomidine (353; 26.7%) and buprenorphine (424; 32.0%). The most frequently administered induction agent was propofol (451; 61.3%), and isoflurane (668; 50.4%) was the most common agent for maintenance of anesthesia. The majority of respondents reported placing intravenous catheters (885; 66.8%), administering crystalloid fluids (689; 52.0%) and providing heat support (1142; 86.3%). Participants reported using perioperative and postoperative analgesia including opioids (791; 59.7%), non-steroidal anti-inflammatory drugs (NSAIDs; 697; 52.6%) and NSAIDs dispensed for home use (665; 50.2%). Cats were commonly released home on the day of surgery (1150; 86.9%), and most participants reported contacting owners for follow-up within 1-2 days (989; 74.7%). CONCLUSIONS AND CLINICAL RELEVANCE: Anesthetic protocols and management techniques for routine feline ovariohysterectomy differ widely among US veterinarians who are VIN members, and results from this study may be of use to evaluate anesthetic practices from this population of veterinarians.

From biomechanics to pathology: predicting axonal injury from patterns of strain after traumatic brain injury.

The relationship between biomechanical forces and neuropathology is key to understanding traumatic brain injury. White matter tracts are damaged by high shear forces during impact, resulting in axonal injury, a key determinant of long-term clinical outcomes. However, the relationship between biomechanical forces and patterns of white matter injuries, associated with persistent diffusion MRI abnormalities, is poorly understood. This limits the ability to predict the severity of head injuries and the design of appropriate protection. Our previously developed human finite element model of head injury predicted the location of post-traumatic neurodegeneration. A similar rat model now allows us to experimentally test whether strain patterns calculated by the model predicts in vivo MRI and histology changes. Using a controlled cortical impact, mild and moderate injuries (1 and 2 mm) were performed. Focal and axonal injuries were quantified with volumetric and diffusion 9.4 T MRI at 2 weeks post injury. Detailed analysis of the corpus callosum was conducted using multi-shell diffusion MRI and histopathology. Microglia and astrocyte density, including process parameters, along with white matter structural integrity and neurofilament expression were determined by quantitative immunohistochemistry. Linear mixed effects regression analyses for strain and strain rate with the employed outcome measures were used to ascertain how well immediate biomechanics could explain MRI and histology changes. The spatial pattern of mechanical strain and strain rate in the injured cortex shows good agreement with the probability maps of focal lesions derived from volumetric MRI. Diffusion metrics showed abnormalities in the corpus callosum, indicating white matter changes in the segments subjected to high strain, as predicted by the model. The same segments also exhibited a severity-dependent increase in glia cell density, white matter thinning and reduced neurofilament expression. Linear mixed effects regression analyses showed that mechanical strain and strain rate were significant predictors of in vivo MRI and histology changes. Specifically, strain and strain rate respectively explained 33% and 28% of the reduction in fractional anisotropy, 51% and 29% of the change in neurofilament expression and 51% and 30% of microglia density changes. The work provides evidence that strain and strain rate in the first milliseconds after injury are important factors in determining patterns of glial and axonal injury and serve as experimental validators of our computational model of traumatic brain injury. Our results provide support for the use of this model in understanding the relationship of biomechanics and neuropathology and can guide the development of head protection systems, such as airbags and helmets.

Vestibular agnosia in traumatic brain injury and its link to imbalance.

Vestibular dysfunction, causing dizziness and imbalance, is a common yet poorly understood feature in patients with TBI. Damage to the inner ear, nerve, brainstem, cerebellum and cerebral hemispheres may all affect vestibular functioning, hence, a multi-level assessment-from reflex to perception-is required. In a previous report, postural instability was the commonest neurological feature in ambulating acute patients with TBI. During ward assessment, we also frequently observe a loss of vertigo sensation in patients with acute TBI, common inner ear conditions and a related vigorous vestibular-ocular reflex nystagmus, suggesting a 'vestibular agnosia'. Patients with vestibular agnosia were also more unbalanced; however, the link between vestibular agnosia and imbalance was confounded by the presence of inner ear conditions. We investigated the brain mechanisms of imbalance in acute TBI, its link with vestibular agnosia, and potential clinical impact, by prospective laboratory assessment of vestibular function, from reflex to perception, in patients with preserved peripheral vestibular function. Assessment included: vestibular reflex function, vestibular perception by participants' report of their passive yaw rotations in the dark, objective balance via posturography, subjective symptoms via questionnaires, and structural neuroimaging. We prospectively screened 918 acute admissions, assessed 146 and recruited 37. Compared to 37 matched controls, patients showed elevated vestibular-perceptual thresholds (patients 12.92°/s versus 3.87°/s) but normal vestibular-ocular reflex thresholds (patients 2.52°/s versus 1.78°/s). Patients with elevated vestibular-perceptual thresholds [3 standard deviations (SD) above controls' average], were designated as having vestibular agnosia, and displayed worse posturography than non-vestibular-agnosia patients, despite no difference in vestibular symptom scores. Only in patients with impaired postural control (3 SD above controls' mean), whole brain diffusion tensor voxel-wise analysis showed elevated mean diffusivity (and trend lower fractional anisotropy) in the inferior longitudinal fasciculus in the right temporal lobe that correlated with vestibular agnosia severity. Thus, impaired balance and vestibular agnosia are co-localized to the inferior longitudinal fasciculus in the right temporal lobe. Finally, a clinical audit showed a sevenfold reduction in clinician recognition of a common peripheral vestibular condition (benign paroxysmal positional vertigo) in acute patients with clinically apparent vestibular agnosia. That vestibular agnosia patients show worse balance, but without increased dizziness symptoms, explains why clinicians may miss treatable vestibular diagnoses in these patients. In conclusion, vestibular agnosia mediates imbalance in traumatic brain injury both directly via white matter tract damage in the right temporal lobe, and indirectly via reduced clinical recognition of common, treatable vestibular diagnoses.

Item-level analysis of mental health symptom trajectories during the COVID-19 pandemic in the UK: Associations with age, sex and pre-existing psychiatric conditions.

BACKGROUND: There is widespread concern regarding how the COVID-19 pandemic has affected mental health. Emerging meta-analyses suggest that the impact on anxiety/depression may have been transient, but much of the included literature has major methodological limitations. Addressing this topic rigorously requires longitudinal data of sufficient scope and scale, controlling for contextual variables, with baseline data immediately pre-pandemic. AIMS: To analyse self-report of symptom frequency from two largely UK-based longitudinal cohorts: Cohort 1 (N = 10,475, two time-points: winter pre-pandemic to UK first winter resurgence), and Cohort 2 (N = 10,391, two time-points, peak first wave to UK first winter resurgence). METHOD: Multinomial logistic regression applied at the item level identified sub-populations with greater probability of change in mental health symptoms. Permutation analyses characterised changes in symptom frequency distributions. Cross group differences in symptom stability were evaluated via entropy of response transitions. RESULTS: Anxiety was the most affected aspect of mental health. The profiles of change in mood symptoms was less favourable for females and older adults. Those with pre-existing psychiatric diagnoses showed substantially higher probability of very frequent symptoms pre-pandemic and elevated risk of transitioning to the highest levels of symptoms during the pandemic. Elevated mental health symptoms were evident across intra-COVID timepoints in Cohort 2. CONCLUSIONS: These findings suggest that mental health has been negatively affected by the pandemic, including in a sustained fashion beyond the first UK lockdown into the first winter resurgence. Women, and older adults, were more affected relative to their own baselines. Those with diagnoses of psychiatric conditions were more likely to experience transition to the highest levels of symptom frequency.

Anesthetic and analgesic techniques used for dogs undergoing ovariohysterectomies in general practice in the United States.

OBJECTIVE: To acquire information about anesthesia and analgesia protocols used by United States (US) veterinarians in primary care practices when performing routine ovariohysterectomy in dogs. STUDY DESIGN: Cross-sectional survey. POPULATION: Primary care veterinarians in the US. METHODS: An online anonymous survey, originally created in New Zealand, was modified with permission and made available to Veterinary Information Network (VIN) members. The survey asked questions about performing ovariohysterectomy in healthy adolescent dogs in the categories of preanesthetic evaluation, premedication and induction protocols, maintenance protocols and monitoring equipment, and postoperative analgesic and sedation protocols and pain assessments. RESULTS: A total of 1213 US veterinarians completed the survey. Respondents (n; %) reported performing preoperative laboratory tests [packed cell volume (135; 11%), complete blood cell count (889; 73%) and biochemistry panels (1057; 87%)] and preanesthetic examinations on the morning of surgery (1083; 90%). The most commonly administered drugs for premedication were acepromazine (512; 42%), hydromorphone (475; 39%) or butorphanol (463; 38%), with propofol (637; 67%) for induction of anesthesia and isoflurane (882; 73%) for maintenance of anesthesia. Most veterinarians reported placing intravenous catheters (945; 78%), administering electrolyte solutions (747; 67%) and providing heat support (1160; 96%). Perioperative and postoperative analgesia included local anesthetics (545; 45%), opioids (844; 70%) and non-steroidal anti-inflammatory drugs (NSAIDs) (953; 79%); NSAIDs were dispensed for home use (985; 81%). Dogs were most frequently discharged on the day of surgery (1068; 88%) and the owners were contacted (914; 75%) for follow-up within 1-2 days. CONCLUSIONS AND CLINICAL RELEVANCE: Anesthetic management for routine ovariohysterectomy in dogs varies among US veterinary VIN members. Information from this study is useful for all veterinarians for comparison with their practice management and for teachers of veterinary anesthesia to continue to emphasize options for analgesia.

American and Canadian veterinarians' perceptions on dog and cat core vaccination rates and the impact of the human medicine anti-vaxx movement on veterinary medicine.

An electronic survey was distributed to assess American and Canadian veterinarians' perceptions on dog and cat vaccination rates. The top veterinarian concerns for vaccinating a healthy adult dog were anaphylaxis, soreness at the injection site, and lethargy; for cats, these concerns included vaccine-associated sarcoma, lethargy, and soreness at injection site. Veterinarians reported that the most common concerns mentioned by reluctant or resistant clients to vaccinating their dogs or cats were beliefs that vaccinations are costly and unnecessary or may lead to chronic or severe illness. There was a positive correlation between an organized anti-vaxx movement against mandatory vaccination for children in their community and the number of vaccine resistant or concerned clients. That the number of resistant clients was associated with the presence of an organized anti-vaxx movement implies that the human anti-vaxx movement is impacting pet owners' views on companion animal vaccinations.

Perceptions des vétérinaires américains et canadiens sur les taux de vaccination de base des chiens et des chats et impact du mouvement anti-vaxx en médecine humaine sur la médecine vétérinaire. Un sondage électronique a été distribué pour évaluer les perceptions des vétérinaires américains et canadiens sur les taux de vaccination des chiens et des chats. Les principales préoccupations des vétérinaires pour la vaccination d'un chien adulte en bonne santé étaient l'anaphylaxie, la douleur au site d'injection et la léthargie; pour les chats, ces préoccupations comprenaient le sarcome associé au vaccin, la léthargie et la douleur au site d'injection. Les vétérinaires ont signalé que les préoccupations les plus courantes mentionnées par les clients réticents ou résistants à la vaccination de leurs chiens ou chats étaient la croyance que les vaccinations sont coûteuses et inutiles ou peuvent entraîner une maladie chronique ou grave. Il y avait une corrélation positive entre un mouvement anti-vaxx organisé contre la vaccination obligatoire des enfants de leur communauté et le nombre de clients inquiets ou résistants à la vaccination. Le fait que le nombre de clients résistants soit corrélé à la présence d'un mouvement anti-vaxx organisé suggère que le mouvement anti-vaxx en médicine humaine a un impact sur l'opinion des propriétaires d'animaux de compagnie sur la vaccination des animaux de compagnie.(Traduit par Dr Serge Messier).

An automated machine learning approach to predict brain age from cortical anatomical measures.

The use of machine learning (ML) algorithms has significantly increased in neuroscience. However, from the vast extent of possible ML algorithms, which one is the optimal model to predict the target variable? What are the hyperparameters for such a model? Given the plethora of possible answers to these questions, in the last years, automated ML (autoML) has been gaining attention. Here, we apply an autoML library called Tree-based Pipeline Optimisation Tool (TPOT) which uses a tree-based representation of ML pipelines and conducts a genetic programming-based approach to find the model and its hyperparameters that more closely predicts the subject's true age. To explore autoML and evaluate its efficacy within neuroimaging data sets, we chose a problem that has been the focus of previous extensive study: brain age prediction. Without any prior knowledge, TPOT was able to scan through the model space and create pipelines that outperformed the state-of-the-art accuracy for Freesurfer-based models using only thickness and volume information for anatomical structure. In particular, we compared the performance of TPOT (mean absolute error [MAE]: 4.612 ± .124 years) and a relevance vector regression (MAE 5.474 ± .140 years). TPOT also suggested interesting combinations of models that do not match the current most used models for brain prediction but generalise well to unseen data. AutoML showed promising results as a data-driven approach to find optimal models for neuroimaging applications.

Veterinary Behavior: Assessment of Veterinarians' Training, Experience, and Comfort Level with Cases.

Studies of US animal shelters consistently indicate that behavior is often a major reason for relinquishment and, thereby, euthanasia of millions of dogs and cats annually. Even though this is an area in which veterinarians can intervene to support the human-animal bond, prior research has documented that they frequently do not bring the topic up during appointments. This study explored veterinarians' training in animal behavior and behavioral medicine, along with their level of comfort in treating common behavioral problems. An online survey of practicing veterinarians (N = 1,085) found that only 42.8% felt they'd received a significant amount of training in this field during veterinary school, but the majority reported participating in continuing education sessions about behavior. Almost all respondents reported seeing patients with behavioral issues (99.6%), even when the initial appointment was made for other reasons. Participants felt most comfortable discussing inappropriate elimination and begging for food but were least comfortable treating issues involving aggression. Most veterinarians treat their own behavior cases, using a combination of behavior modification techniques and medication. Only 22.1% refer cases needing behavioral therapy to a specialist. Given the prevalence of behavioral problems in companion animals and the potential for early veterinary intervention to play a significant role in animal health, it is important for veterinary schools to include this topic in their curricula. At present, 73% of schools require a course in animal behavior. The release of the new Competency-Based Veterinary Education framework is anticipated to support a greater teaching emphasis in this area.

Altered caudate connectivity is associated with executive dysfunction after traumatic brain injury.

Traumatic brain injury often produces executive dysfunction. This characteristic cognitive impairment often causes long-term problems with behaviour and personality. Frontal lobe injuries are associated with executive dysfunction, but it is unclear how these injuries relate to corticostriatal interactions that are known to play an important role in behavioural control. We hypothesized that executive dysfunction after traumatic brain injury would be associated with abnormal corticostriatal interactions, a question that has not previously been investigated. We used structural and functional MRI measures of connectivity to investigate this. Corticostriatal functional connectivity in healthy individuals was initially defined using a data-driven approach. A constrained independent component analysis approach was applied in 100 healthy adult dataset from the Human Connectome Project. Diffusion tractography was also performed to generate white matter tracts. The output of this analysis was used to compare corticostriatal functional connectivity and structural integrity between groups of 42 patients with traumatic brain injury and 21 age-matched controls. Subdivisions of the caudate and putamen had distinct patterns of functional connectivity. Traumatic brain injury patients showed disruption to functional connectivity between the caudate and a distributed set of cortical regions, including the anterior cingulate cortex. Cognitive impairments in the patients were mainly seen in processing speed and executive function, as well as increased levels of apathy and fatigue. Abnormalities of caudate functional connectivity correlated with these cognitive impairments, with reductions in right caudate connectivity associated with increased executive dysfunction, information processing speed and memory impairment. Structural connectivity, measured using diffusion tensor imaging between the caudate and anterior cingulate cortex was impaired and this also correlated with measures of executive dysfunction. We show for the first time that altered subcortical connectivity is associated with large-scale network disruption in traumatic brain injury and that this disruption is related to the cognitive impairments seen in these patients.

Neural correlates of the LSD experience revealed by multimodal neuroimaging.

Lysergic acid diethylamide (LSD) is the prototypical psychedelic drug, but its effects on the human brain have never been studied before with modern neuroimaging. Here, three complementary neuroimaging techniques: arterial spin labeling (ASL), blood oxygen level-dependent (BOLD) measures, and magnetoencephalography (MEG), implemented during resting state conditions, revealed marked changes in brain activity after LSD that correlated strongly with its characteristic psychological effects. Increased visual cortex cerebral blood flow (CBF), decreased visual cortex alpha power, and a greatly expanded primary visual cortex (V1) functional connectivity profile correlated strongly with ratings of visual hallucinations, implying that intrinsic brain activity exerts greater influence on visual processing in the psychedelic state, thereby defining its hallucinatory quality. LSD's marked effects on the visual cortex did not significantly correlate with the drug's other characteristic effects on consciousness, however. Rather, decreased connectivity between the parahippocampus and retrosplenial cortex (RSC) correlated strongly with ratings of "ego-dissolution" and "altered meaning," implying the importance of this particular circuit for the maintenance of "self" or "ego" and its processing of "meaning." Strong relationships were also found between the different imaging metrics, enabling firmer inferences to be made about their functional significance. This uniquely comprehensive examination of the LSD state represents an important advance in scientific research with psychedelic drugs at a time of growing interest in their scientific and therapeutic value. The present results contribute important new insights into the characteristic hallucinatory and consciousness-altering properties of psychedelics that inform on how they can model certain pathological states and potentially treat others.

Canadian dog owners' use and perceptions of cannabis products.

The legal market for recreational and medicinal cannabis for human consumption is growing worldwide. At the same time, marketing of cannabis products for use in pets is expanding. Yet, there is little research exploring the effects of cannabis use in veterinary medicine. This study used an anonymous, online survey to assess Canadian pet owners' reasons for purchasing cannabis products for their dogs, and their perceptions regarding efficacy of these treatments. Owners purchased cannabis products for treatment of pain, inflammation, and anxiety in dogs, and perceived these preparations to be equally or more effective than conventional medications. Most owners reported only minimal side effects in their dogs. Despite indicating comfort in discussing canine cannabis administration with their veterinarian, most owners relied on commercial websites for product information. The main reasons for choosing cannabis products were the ability to use as an adjuvant to other therapies, and the perception of it being a natural substance. Given this information, it is incumbent upon veterinarians to appropriately counsel their clients, and also to advocate for evidence-based studies to evaluate the efficacy of cannabis use in non-human species.

Usage du cannabis et perceptions à l'égard de ce produit parmi les propriétaires canadiens de chiens. Le marché légal pour le cannabis récréatif et médicinal pour la consommation humaine affiche une croissance à l'échelle mondiale. La commercialisation des produits de cannabis pour utilisation chez les animaux de compagnie connaît une croissance. Pourtant, peu de travaux de recherche ont exploré les effets de l'usage du cannabis en médecine vétérinaire. Cette étude a mené un sondage en ligne anonyme pour évaluer les raisons des propriétaires canadiens d'animaux de compagnie d'acheter des produits de cannabis pour leurs chiens et leurs perceptions concernant l'efficacité de ces traitements. Les propriétaires ont acheté des produits de cannabis pour le traitement de la douleur, de l'inflammation et de l'anxiété chez les chiens et ils percevaient ces préparations comme étant tout autant ou plus efficaces que les médicaments conventionnels. La plupart des propriétaires ont signalé des effets secondaires minimaux chez leurs chiens. Malgré avoir indiqué de l'aise pour la discussion de l'administration de cannabis à leur chien avec leur vétérinaire, la plupart des propriétaires se fiaient à des sites Web commerciaux pour obtenir de l'information sur les produits. Les principales raisons pour le choix de produits de cannabis étaient la capacité de l'utiliser comme adjuvant pour les autres thérapies et la perception que c'était une substance naturelle. Compte tenu de ces renseignements, il incombe aux vétérinaires de bien conseiller leurs clients et aussi de préconiser des études factuelles pour évaluer l'efficacité de l'usage du cannabis chez des espèces non humaines.(Traduit par Isabelle Vallières).

Veterinary Student Stress, the Benefit of Canine Pets, and Potential Institutional Support of Dog Ownership.

The stress of veterinary school and the high prevalence of psychological distress among veterinary students have been well documented. Pet ownership is known to improve overall health and reduce stress among the public. Yet, for veterinary students, owning a pet (especially a dog) can offer both rewards and challenges. The academic schedule for veterinary students often comprises long hours that can make caring for a dog challenging. This study explores the area of veterinary students' dog care options and perspectives by examining two aspects of this issue: (a) currently available options, as reported by academic administrators, and (b) perceived need for these options, as reported by veterinary students. A survey of associate deans for academic affairs (n = 30) found that routine on-site kenneling options for student-owned dogs are available at eight (26.6%) veterinary schools. Simultaneously, results of a student survey (n = 768) revealed a great desire for on-campus services. Among students who did not have access to on-campus kenneling facilities, 71.5% (453 of 634) felt that creating these options would be important or very important. Across all students surveyed, 76% (581 of 764) felt it would be important to have on-site dog housing/care available. Students experience considerable stress over having to find accommodations or care for their dogs while engaged in academic activities. Thus, providing on-site boarding and care options for student-owned dogs can play an important role in both recruiting prospective veterinary students and enhancing the well-being of those currently in the program.

Serum insulin-like growth factor-I levels are associated with improved white matter recovery after traumatic brain injury.

OBJECTIVE: Traumatic brain injury (TBI) is a common disabling condition with limited treatment options. Diffusion tensor imaging measures recovery of axonal injury in white matter (WM) tracts after TBI. Growth hormone deficiency (GHD) after TBI may impair axonal and neuropsychological recovery, and serum insulin-like growth factor-I (IGF-I) may mediate this effect. We conducted a longitudinal study to determine the effects of baseline serum IGF-I concentrations on WM tract and neuropsychological recovery after TBI. METHODS: Thirty-nine adults after TBI (84.6% male, median age = 30.5 years, 87.2% moderate-severe, median time since TBI = 16.3 months, n = 4 with GHD) were scanned twice, 13.3 months (range = 12.1-14.9) apart, and 35 healthy controls were scanned once. Symptom and quality of life questionnaires and cognitive assessments were completed at both visits (n = 33). Our main outcome measure was fractional anisotropy (FA), a measure of WM tract integrity, in a priori regions of interest: splenium of corpus callosum (SPCC) and posterior limb of internal capsule (PLIC). RESULTS: At baseline, FA was reduced in many WM tracts including SPCC and PLIC following TBI compared to controls, indicating axonal injury, with longitudinal increases indicating axonal recovery. There was a significantly greater increase in SPCC FA over time in patients with serum IGF-I above versus below the median for age. Only the higher IGF-I group had significant improvements in immediate verbal memory recall over time. INTERPRETATION: WM recovery and memory improvements after TBI were greater in patients with higher serum IGF-I at baseline. These findings suggest that the growth hormone/IGF-I system may be a potential therapeutic target following TBI. Ann Neurol 2017;82:30-43.

From homeostasis to behavior: Balanced activity in an exploration of embodied dynamic environmental-neural interaction.

In recent years, there have been many computational simulations of spontaneous neural dynamics. Here, we describe a simple model of spontaneous neural dynamics that controls an agent moving in a simple virtual environment. These dynamics generate interesting brain-environment feedback interactions that rapidly destabilize neural and behavioral dynamics demonstrating the need for homeostatic mechanisms. We investigate roles for homeostatic plasticity both locally (local inhibition adjusting to balance excitatory input) as well as more globally (regional "task negative" activity that compensates for "task positive", sensory input in another region) balancing neural activity and leading to more stable behavior (trajectories through the environment). Our results suggest complementary functional roles for both local and macroscale mechanisms in maintaining neural and behavioral dynamics and a novel functional role for macroscopic "task-negative" patterns of activity (e.g., the default mode network).

Computational modelling of traumatic brain injury predicts the location of chronic traumatic encephalopathy pathology.

Traumatic brain injury can lead to the neurodegenerative disease chronic traumatic encephalopathy. This condition has a clear neuropathological definition but the relationship between the initial head impact and the pattern of progressive brain pathology is poorly understood. We test the hypothesis that mechanical strain and strain rate are greatest in sulci, where neuropathology is prominently seen in chronic traumatic encephalopathy, and whether human neuroimaging observations converge with computational predictions. Three distinct types of injury were simulated. Chronic traumatic encephalopathy can occur after sporting injuries, so we studied a helmet-to-helmet impact in an American football game. In addition, we investigated an occipital head impact due to a fall from ground level and a helmeted head impact in a road traffic accident involving a motorcycle and a car. A high fidelity 3D computational model of brain injury biomechanics was developed and the contours of strain and strain rate at the grey matter-white matter boundary were mapped. Diffusion tensor imaging abnormalities in a cohort of 97 traumatic brain injury patients were also mapped at the grey matter-white matter boundary. Fifty-one healthy subjects served as controls. The computational models predicted large strain most prominent at the depths of sulci. The volume fraction of sulcal regions exceeding brain injury thresholds were significantly larger than that of gyral regions. Strain and strain rates were highest for the road traffic accident and sporting injury. Strain was greater in the sulci for all injury types, but strain rate was greater only in the road traffic and sporting injuries. Diffusion tensor imaging showed converging imaging abnormalities within sulcal regions with a significant decrease in fractional anisotropy in the patient group compared to controls within the sulci. Our results show that brain tissue deformation induced by head impact loading is greatest in sulcal locations, where pathology in cases of chronic traumatic encephalopathy is observed. In addition, the nature of initial head loading can have a significant influence on the magnitude and pattern of injury. Clarifying this relationship is key to understanding the long-term effects of head impacts and improving protective strategies, such as helmet design.

Chaos in homeostatically regulated neural systems.

Low-dimensional yet rich dynamics often emerge in the brain. Examples include oscillations and chaotic dynamics during sleep, epilepsy, and voluntary movement. However, a general mechanism for the emergence of low dimensional dynamics remains elusive. Here, we consider Wilson-Cowan networks and demonstrate through numerical and analytical work that homeostatic regulation of the network firing rates can paradoxically lead to a rich dynamical repertoire. The dynamics include mixed-mode oscillations, mixed-mode chaos, and chaotic synchronization when the homeostatic plasticity operates on a moderately slower time scale than the firing rates. This is true for a single recurrently coupled node, pairs of reciprocally coupled nodes without self-coupling, and networks coupled through experimentally determined weights derived from functional magnetic resonance imaging data. In all cases, the stability of the homeostatic set point is analytically determined or approximated. The dynamics at the network level are directly determined by the behavior of a single node system through synchronization in both oscillatory and non-oscillatory states. Our results demonstrate that rich dynamics can be preserved under homeostatic regulation or even be caused by homeostatic regulation.

Use of Short Animal-Themed Videos to Enhance Veterinary Students' Mood, Attention, and Understanding of Pharmacology Lectures.

Professional DVM training is inherently stressful and challenging for students. This study evaluated a simple intervention-short breaks during a veterinary pharmacology lecture course in the form of funny/cute animal videos (Mood Induction Procedures, or MIP)-to assess for potential impact on students' mood, interest in material, and perceived understanding of material. Ten YouTube video clips showing cats or dogs were selected to influence students' affective states. The videos were shown in a required pharmacology class offered during the fall semester of the second year of the DVM program at a large, land-grant institution in the western US. The student cohort consisted of 133 students (20 males, 113 females). Twenty days of the course were randomly chosen for the study and ranged from weeks 2 to 13 of the semester. Sessions in which the videos were played were alternated with sessions in which no video was played, for a total of 10 video days and 10 control days. There were significant differences in all three post-class assessment measures between the experimental (video) days and the control days. Results suggest that showing short cute animal videos in the middle of class positively affected students' mood, interest in material, and self-reported understanding of material. While the results of this study are limited to one student cohort at one institution, the ease of implementation of the technique and relatively low stakes support incorporation of the MIP technique across a variety of basic and clinical science courses.

Protein synthesis is associated with high-speed dynamics and broad-band stability of functional hubs in the brain.

L-[1-11C]leucine PET can be used to measure in vivo protein synthesis in the brain. However, the relationship between regional protein synthesis and on-going neural dynamics is unclear. We use a graph theoretical approach to examine the relationship between cerebral protein synthesis (rCPS) and both static and dynamical measures of functional connectivity (measured using resting state functional MRI, R-fMRI). Our graph theoretical analysis demonstrates a significant positive relationship between protein turnover and static measures of functional connectivity. We compared these results to simple measures of metabolism in the cortex using [18F]FDG PET). Whilst some relationships between [18F]FDG binding and graph theoretical measures was present, there remained a significant relationship between protein turnover and graph theoretical measures, which were more robustly explained by L-[1-11C]Leucine than [18F]FDG PET. This relationship was stronger in dynamics at a faster temporal resolution relative to dynamics measured over a longer epoch. Using a Dynamic connectivity approach, we also demonstrate that broad-band dynamic measures of Functional Connectivity (FC), are inversely correlated with protein turnover, suggesting greater stability of FC in highly interconnected hub regions is supported by protein synthesis. Overall, we demonstrate that cerebral protein synthesis has a strong relationship independent of tissue metabolism to neural dynamics at the macroscopic scale.