Blunt impacts to the back: Biomechanical response for model development

The development of advanced injury prediction models requires biomechanical and injury tolerance information for all regions of the body. While numerous studies have investigated injury mechanics of the thorax under frontal impact, there remains a dearth of information on the injury mechanics of the torso under blunt impact to the back. A series of hub-impact tests were performed to the back surface of the mid-thorax of four mid-size male cadavers. Repeated tests were performed to characterize the biomechanical and injury response of the thorax under various impact speeds (1.5m/s, 3m/s and 5.5m/s). Deformation of the chest was recorded with a 59-gage chestband. Subject kinematics were also recorded with a high-speed optoelectronic 3D motion capture system. In the highest-severity tests, peak impact forces ranged from 6.9 to 10.5kN. The peak change in extension angle measured between the 1st thoracic vertebra and the lumbar spine ranged from 39 to 62°. The most commonly observed injuries were strains of the costovertebral/costotransverse joint complexes, rib fractures, and strains of the interspinous and supraspinous ligaments. The majority of the rib fractures occurred in the rib neck between the costovertebral and costotransverse joints. The prevalence of rib-neck fractures suggests a novel, indirect loading mechanism resulting from bending moments generated in the rib necks caused by motion of the spine. In addition to the injury information, the biomechanical responses quantified here will facilitate the future development and validation of human body models for predicting injury risk during impact to the back

Side-bias and time-of-day influenced cognition after minipigs were conditioned using a novel tactile stimulation device

Agricultural and clinical research communities seek objective tools to detect and track prepathological states for prevention, disease-treatment, and therapeutics. We propose a novel, quantitative approach to test the functional state of the somatosensory system and detect aberrations in neurophysiology associated with prepathological injury or sickness. Leveraging the evolutionarily preserved concepts of lateral inhibition and parallel processing, the human version of this approach can detect the slightest changes in brain health. However, an animal model is needed to benefit and translate results to both agriculture and clinical researchers. The objective of this study was to refine methodologies for the use of tactile stimulation (TS; vibration at 75 Hz for 1 s; Porcine Brain Gauge; Cortical Metrics, North Carolina) to condition and test a pigs ability to associate right-TS with a right-ball and left-TS with a left-toy during 12 tests (right and left tested every test). Minipigs (n = 8; boars = 7 gilt = 1; NSRRC, Columbia, MO) were used to determine the effects of: 1) placement of two TS-devices (sides or behind ears); 2) right- or left-bowl bias, time (1000 h or 0300 h) and; 3) day (6 test consecutive days). Pig with ear-placement spent more time at the correct bowl than pigs with side-placement (P = 0.05). All pigs spent more time (P = 0.02) in the correct-bowl area and tended to have a greater correct-index (P = 0.09) if the first test administered was on the right than when the test started on the left. Pigs tended (P = 0.06) to spend less time making a decision and spent more time at the correct bowl (P < 0.01) in the morning tests than evening tests. In addition, all pigs spent less time at the correct bowl and decreased correct frequency after each day (P < 0.05). Future studies will be designed to repeat tests for side-bias and take place in the mornings, after feeding. The effects of day suggest that pigs became bored over time, therefore, future experiments will include more operant-conditioned tasks to test motivation, and physical barriers to restrict movement after the subject enters the right- or left-bowl area