Comparison of alterations in local field potentials and neuronal firing in mouse M1 and CA1 associated with central fatigue induced by high-intensity interval training and moderate-intensity continuous training.

Background: The mechanisms underlying central fatigue (CF) induced by high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) are still not fully understood.

Methods: In order to explore the effects of these exercises on the functioning of cortical and subcortical neural networks, this study investigated the effects of HIIT and MICT on local field potential (LFP) and neuronal firing in the mouse primary motor cortex (M1) and hippocampal CA1 areas. HIIT and MICT were performed on C57BL/6 mice, and simultaneous multichannel recordings were conducted in the M1 motor cortex and CA1 hippocampal region.

Incidents and patterns of among athletes in the USA from 1982 to 2023.

Introduction: is a rare event that occurs following blunt, non-penetrating trauma to the chest, precipitating a ventricular arrhythmia. requires immediate medical attention through cardiopulmonary resuscitation and defibrillation, often resulting in death. is most common condition among young male athletes.

Modified Mouse Model of Repetitive Mild Traumatic Brain Injury Incorporating Thinned-Skull Window and Fluid Percussion.

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models with well-defined pathologies are urgently needed for studying the mechanisms of neuropathology after mild TBI and testing therapeutics. Replicating the entire sequelae of TBI in animal models has proven to be a challenge.

Comprehensively characterizing heterogeneous and transversely isotropic properties of femur cortical bones.

Comprehensive characterization of the transversely isotropic mechanical properties of long bones along both the longitudinal and circumferential gradients is crucial for developing accurate mathematical models and studying bone biomechanics. In addition, mechanical testing to derive elastic, plastic, and failure properties of bones is essential for modeling plastic deformation and failure of bones. To achieve these, we machined a total of 336 cortical specimens, including 168 transverse and 168 longitudinal specimens, from four different quadrants of seven different sections of 3 bovine femurs.

Understanding Head Injury Risks During Car-to-Pedestrian Collisions Using Realistic Vehicle and Detailed Human Body Models.

Traumatic brain injury (TBI) is the leading cause of death and long-term disability in road traffic accidents (RTAs). Researchers have examined the effect of vehicle front shape and pedestrian body size on the risk of pedestrian head injury. On the other hand, the relationship between vehicle front shape parameters and pedestrian TBI risks involving a diverse population with varying body sizes has yet to be investigated.

Advancing Commotio cordis Safety Standards Using the Total Human Models for Safety (THUMS).

Commotio cordis is one of the leading causes of sudden cardiac death in youth baseball. Currently, there are chest protector regulations regarding the prevention of Commotio cordis in baseball and lacrosse; however, they are not fully optimized. For the advancement of Commotio cordis safety, it is vital to include various age groups and a variety of impact angles in the testing process.

Mechanical properties of young mice tibia in four circumferential quadrants under nanoindentation.

Characterizing the mechanical properties of different anatomical quadrants of bones has been conducted in the literature to help understand the correlations among bone morphometric, densitometric, and material properties. However, although there are data to compare four quadrants of the long bones of the adult, there is very limited research on the young adult especially young female. Hence, nine tibia mid-shaft specimens were harvested from nine 8-week-old C57BL/6J female mice, which roughly correspond to the age range of juvenile to young adult, with one left tibia being harvested from one animal.

Use of Brain Biomechanical Models for Monitoring Impact Exposure in Contact Sports.

Head acceleration measurement sensors are now widely deployed in the field to monitor head kinematic exposure in contact sports. The wealth of impact kinematics data provides valuable, yet challenging, opportunities to study the biomechanical basis of mild traumatic brain injury (mTBI) and subconcussive kinematic exposure. Head impact kinematics are translated into brain mechanical responses through physics-based computational simulations using validated brain models to study the mechanisms of injury.

The Effect of Three-Dimensional Whole, Major, and Small Vasculature on Mouse Brain Strain Under Both Diffuse and Focal Brain Injury Loading.

Blood vessels are much stiffer than brain parenchyma and their effects in finite element (FE) brain models need to be investigated. Despite the publication of some comprehensive three-dimensional (3D) brain vasculature models, no mechanical model exists for the mouse brain vasculature. Moreover, how the vasculature affects the mechanical behavior of brain tissue remains controversial.

A Neuropathological Study of Diffuse Vascular Injury in Fatal Motor Vehicle Collisions.

In Canada, 42 929 people were involved in fatal motor vehicle collisions (MVCs) between 1999 and 2018. Traumatic brain injuries (TBIs), including diffuse vascular injury (DVI), were the most frequent cause of death. The neuroanatomical injury pattern and severity of DVI in relation to data on MVC dynamics and other MVC factors were the focus of the current study.

Purposeful Heading Performed by Female Youth Soccer Players Leads to Strain Development in Deep Brain Structures.

Head impacts in soccer have been associated with both short- and long-term neurological consequences. Youth players' brains are especially vulnerable given that their brains are still developing, and females are at an increased risk of traumatic brain injury (TBI) compared to males. Approximately 90% of head impacts in soccer occur from purposeful heading.

Identifying Vulnerable Impact Locations to Reduce the Occurrence of Deadly Commotio Cordis Events in Children's Baseball: A Computational Approach.

Commotio cordis is the second leading cause of sudden cardiac death in young athletes. Currently available chest protectors on the market are ineffective in preventing cases of commotio cordis in young athletes who play baseball. This study focused on using contour maps to identify specific baseball impact locations to the chest that may result in instances of commotio cordis to children during baseball games.

Modeling small remotely piloted aircraft system to head impact for investigating craniocerebral response.

Understanding small remotely piloted aircraft system (sRPAS) to human head impacts is needed to better protect human head during sRPAS ground collision accidents. Recent literature reported cadaveric data on sRPAS to human head impacts, which provided a unique opportunity for developing validated computational models. However, there lacks an understanding of skull stress and brain strain during these impacts.

Head Kinematics and Injury Metrics for Laboratory Hockey-Relevant Head Impact Experiments.

Investigating head responses during hockey-related blunt impacts and hence understanding how to mitigate brain injury risk from such impacts still needs more exploration. This study used the recently developed hockey helmet testing methodology, known as the Hockey Summation of Tests for the Analysis of Risk (Hockey STAR), to collect 672 laboratory helmeted impacts. Brain strains were then calculated from the according 672 simulations using the detailed Global Human Body Models Consortium (GHBMC) finite element head model.

Developing commotio cordis injury metrics for baseball safety: unravelling the connection between chest force and rib deformation to left ventricle strain and pressure.

Commotio cordis is a sudden death mechanism that occurs when the heart is impacted during the repolarization phase of the cardiac cycle. This study aimed to investigate commotio cordis injury metrics by correlating chest force and rib deformation to left ventricle strain and pressure. We simulated 128 chest impacts using a simulation matrix which included two initial velocities, 16 impact locations spread across the transverse and sagittal plane, and four baseball stiffness levels.

Brain microvascular damage linked to a moderate level of strain induced by controlled cortical impact.

Cerebral blood vessels play an important role in brain metabolic activity in general and following traumatic brain injury (TBI) in particular. However, the extent to which TBI alters microvessel structure is not well understood. Specifically, how intracranial mechanical responses produced during impacts relate to vascular damage needs to be better studied.

Repetitive mild traumatic brain injury in mice triggers a slowly developing cascade of long-term and persistent behavioral deficits and pathological changes.

We have previously reported long-term changes in the brains of non-concussed varsity rugby players using magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI) and functional magnetic imaging (fMRI). Others have reported cognitive deficits in contact sport athletes that have not met the diagnostic criteria for concussion. These results suggest that repetitive mild traumatic brain injuries (rmTBIs) that are not severe enough to meet the diagnostic threshold for concussion, produce long-term consequences.

Animal Orientation Affects Brain Biomechanical Responses to Blast-Wave Exposure.

In this study, we investigated how animal orientation within a shock tube influences the biomechanical responses of the brain and cerebral vasculature of a rat when exposed to a blast wave. Using three-dimensional finite element (FE) models, we computed the biomechanical responses when the rat was exposed to the same blast-wave overpressure (100 kPa) in a prone (P), vertical (V), or head-only (HO) orientation. We validated our model by comparing the model-predicted and the experimentally measured brain pressures at the lateral ventricle.

Is the 0.2%-Strain-Offset Approach Appropriate for Calculating the Yield Stress of Cortical Bone?

The 0.2% strain offset approach is mostly used to calculate the yield stress and serves as an efficient method for cross-lab comparisons of measured material properties. However, it is difficult to accurately determine the yield of the bone.

Mechanisms and variances of rotation-induced brain injury: a parametric investigation between head kinematics and brain strain.

There lacks a comprehensive understanding of the correlation between head kinematics and brain strain especially deep-brain strain, partially resulting the deficiency of understanding brain injury mechanisms and the difficulty of choosing appropriate brain injury metrics. Hence, we simulated 76 impacts that were focused on concussion-relevant rotational kinematics and evaluated cumulative strain damage measure (CSDM) and average strain that could represent brain strain distribution. For the whole brain, axial rotation induced the highest CSDM, while lateral bending produced the lowest CSDM.

Porcine growth plate experimental study and estimation of human pediatric growth plate properties.

Growth plate (GP) is a type of tissue widely found in child's immature skeleton. It may have significant influence on the overall injury pattern since it has distinguishing mechanical properties compared to the surrounding bony tissue. For more accurate material modeling and advanced pediatric human body modeling, it is imperative to investigate the material property of GPs in different loading conditions.

A 3-D Rat Brain Model for Blast-Wave Exposure: Effects of Brain Vasculature and Material Properties.

Exposure to blast waves is suspected to cause primary traumatic brain injury. However, existing finite-element (FE) models of the rat head lack the necessary fidelity to characterize the biomechanical responses in the brain due to blast exposure. They neglect to represent the cerebral vasculature, which increases brain stiffness, and lack the appropriate brain material properties characteristic of high strain rates observed in blast exposures.

The Effect of Formalin Preservation Time and Temperature on the Material Properties of Bovine Femoral Cortical Bone Tissue.

Literature has reported controversial findings on whether formalin affected bone properties, or not, especially when different preservation time durations and temperatures were involved. Hence, accurately and systematically quantifying the effect of formalin on the mechanical properties of bone using a large dataset is crucial for assessing biomechanical responses based on fixed specimens. A total of 154 longitudinal and 149 transverse cuboid-shaped (12 mm × 2 mm × 0.

Creating a human head finite element model using a multi-block approach for predicting skull response and brain pressure.

To better understand head injuries, human head finite element (FE) models have been reported in the literature. In scenarios where the head is directly impacted and measurements of head accelerations are not available, a high-quality skull model, as well as a high-quality brain model, is needed to predict the effect of impact on the brain through the skull. Furthermore, predicting cranial bone fractures requires comprehensively validated skull models.

Quantifying the Effect of Repeated Impacts and Lateral Tip Movements on Brain Responses during Controlled Cortical Impact.

Controlled cortical impact (CCI) is a widely used laboratory neurotrauma model to study traumatic brain injury. During CCI, the brain is damaged by an impactor tip, which travels along its axial direction to a pre-defined depth at a pre-set speed. A recent study, however, using high-speed imaging analysis demonstrated that the impactor tip of an electromagnetically driven CCI device experienced repeated impacts and lateral movements, rather than a single axial impact.