Basic NeuroscienceFluid percussion injury device for the precise control of injury parameters

- A novel fluid percussion injury (FPI) system was designed and built.
- The system generated fluid percussions with independently adjustable peak pressures, rise times and impulses.
- Immediate post-injury behavior was similar between the custom FPI system and the commonly used FPI system.
- Fluoro-Jade labeling in the hilus and CA2-3 and granule cell population spike amplitude were consistent between systems.
- Slow fluid percussion rise times increased mortality and reduced motor function in a subset of adult rats.

BackgroundInjury to the brain can occur from a variety of physical insults and the degree of disability can greatly vary from person to person. It is likely that injury outcome is related to the biomechanical parameters of the traumatic event such as magnitude, direction and speed of the forces acting on the head.New methodTo model variations in the biomechanical injury parameters, a voice coil driven fluid percussion injury (FPI) system was designed and built to generate fluid percussion waveforms with adjustable rise times, peak pressures, and durations. Using this system, pathophysiological outcomes in the rat were investigated and compared to animals injured with the same biomechanical parameters using the pendulum based FPI system.Results in comparison with existing methodsImmediate post-injury behavior shows similar rates of seizures and mortality in adolescent rats and similar righting times, toe pinch responses and mortality rates in adult rats. Interestingly, post injury mortality in adult rats was sensitive to changes in injury rate. Fluoro-Jade labeling of degenerating neurons in the hilus and CA2-3 hippocampus were consistent between injuries produced with the voice coil and pendulum operated systems. Granule cell population spike amplitude to afferent activation, a measure of dentate network excitability, also showed consistent enhancement 1 week after injury using either system.ConclusionsOverall our results suggest that this new FPI device produces injury outcomes consistent with the commonly used pendulum FPI system and has the added capability to investigate pathophysiology associated with varying rates and durations of injury.