Age-dependence of intracranial viscoelastic properties in living rats

Shulyakov, Alexander V.; Cenkowski, Stefan; Buist, Richard; Bigio, Marc R. Del

doi:10.1016/j.jmbbm.2010.12.012

Cited by 36 publications

(43 citation statements)

References 109 publications

(111 reference statements)

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“…While not all studies agree brain stiffens with age (Levchakov et al, 2006), the difference in testing methods could lead to large discrepancies in results. In particular, the study of Shulyakov et al (2011) is the most relevant to our experimental configuration where brain properties were tested in vivo with the meningeal compartments intact and is supported of the results of this study.…”

Section: Fluid Percussion Via Motion Controlsupporting

confidence: 73%

“…Interestingly, the irregularity of the fluid percussion waveform appears to be enhanced in the adolescent rat's cranium (Fig. 4) that is generally agreed to be softer and more compliant than the adult (Cheng et al, 2008;Elkin et al, 2010;Elkin and Morrison, 2013;Shulyakov et al, 2011). While not all studies agree brain stiffens with age (Levchakov et al, 2006), the difference in testing methods could lead to large discrepancies in results.…”

Section: Fluid Percussion Via Motion Controlmentioning

confidence: 96%

“…For the vcFPI system, the hydraulic piston must move a greater distance. Accordingly, the irregularity in the slope of the pressure rise may also be in part due to the controller algorithm adjusting to pressure redistribution in the rat's cranium (Abbott, 2004;Schettini and Walsh, 1991;Shulyakov et al, 2011).…”

Section: Fluid Percussion Via Motion Controlmentioning

confidence: 99%

“…Tissues of the brain have viscoelastic behavior (Shuck and Advani, 1972;Cheng et al, 2008;Elkin and Morrison, 2013;Shulyakov et al, 2011;Pamidi and Advani, 1978;Wang and Wineman, 1972). At high rates of loading (peak pressure) viscoelastic materials behave stiffer and the magnitude of injury loading will induce higher stresses in the brain with lower amounts of deformation.…”

Section: Fluid Percussion Via Motion Controlmentioning

confidence: 99%

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Fluid percussion injury device for the precise control of injury parameters

Wahab

Neuberger

Lyeth

et al. 2015

Journal of Neuroscience Methods

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h i g h l i g h t s• 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. a r t i c l e i n f o t r a c tBackground: Injury 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 method: To 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 methods: Immediate 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. Conclusions: Overall 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.

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Section: Fluid Percussion Via Motion Controlsupporting

confidence: 73%

Section: Fluid Percussion Via Motion Controlmentioning

confidence: 96%

Section: Fluid Percussion Via Motion Controlmentioning

confidence: 99%

Section: Fluid Percussion Via Motion Controlmentioning

confidence: 99%

See 2 more Smart Citations

Fluid percussion injury device for the precise control of injury parameters

Wahab

Neuberger

Lyeth

et al. 2015

Journal of Neuroscience Methods

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“…22,27 We have shown that changes in mechanical indentation response from birth to 6 months depend on water content and on tissue protein properties. 26 We have also shown that acute hydrocephalus is associated with only small changes. 25 The purposes of this study were to examine the mechanical properties of living rat intracranial contents following cortical contusion and to correlate these properties with the histological features of the brain tissue.…”

mentioning

confidence: 79%

Intracranial biomechanics following cortical contusion in live rats

Alfasi¹,

Shulyakov

Bigio

2013

JNS

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Object. The goal of this study was to examine the mechanical properties of living rat intracranial contents and corresponding brain structural alterations following parietal cerebral cortex contusion.Methods. After being anesthetized, young adult rats were subjected to parietal craniotomy followed by cortical contusion using a calibrated weight-drop method. Magnetic resonance imaging was used to visualize the contusion. At the site of contusion, instrumented force-controlled indentation was performed 2 hours to 21 days later on the intact dural surface. The force-deformation (stress-strain) relationship was used to calculate elastic (indentation modulus) and strain changes over time, and constant hold or cyclic stress was used to evaluate viscoelastic deformation. These measurements were followed by histological studies.Results. At contusion sites, the indentation modulus was significantly decreased at 1-3 days and tended to be above control values at 21 days. Multicycle indentation showed that the brain tended to accumulate more strain (an indicator of viscosity) by 1 day after the contusion. Imaging and histological studies showed local edema and hemorrhage at 6 hours to 3 days and accumulation of reactive astrocytes, which began at 3 days and was pronounced by 21 days.Conclusions. The viscoelastic properties of living rat brain change following contusion. Initially, edema and tissue necrosis occur, and the brain becomes less elastic and less viscous. Later, along with undergoing reactive astroglial changes, the brain tends to become stiffer than normal. These quantitative data, which are related to the physical changes in the brain following trauma and which reflect subjective impressions upon palpation, will be useful for understanding emerging diagnostic tools such as magnetic resonance elastography.

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Non-ideal effects in indentation testing of soft tissues

Finan

Fox

Morrison

2013

Biomech Model Mechanobiol

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Indentation has several advantages as a loading mode for determining constitutive behavior of soft, biological tissues. However, indentation induces a complex, spatially heterogeneous deformation field that creates analytical challenges for the calculation of constitutive parameters. As a result, investigators commonly assume small indentation depths and large sample thicknesses to simplify analysis and then restrict indentation depth and sample geometry to satisfy these assumptions. These restrictions limit experimental resolution in some fields, such as brain biomechanics. However, recent experimental evidence suggests that conventionally applied limits are in fact excessively conservative. We conducted a parametric study of indentation loading with various indenter geometries, surface interface conditions, sample compressibility, sample geometry and indentation depth to quantitatively describe the deviation from previous treatments that results from violation of the assumptions of small indentation depth and large sample thickness. We found that the classical solution was surprisingly robust to violation of the assumption of small strain but highly sensitive to violation of the assumption of large sample thickness, particularly if the indenter was cylindrical. The ramifications of these findings for design of indentation experiments are discussed and correction factors are presented to allow future investigators to account for these effects without recreating our finite element models.

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Age-dependence of intracranial viscoelastic properties in living rats

Cited by 36 publications

References 109 publications

Fluid percussion injury device for the precise control of injury parameters

Fluid percussion injury device for the precise control of injury parameters

Intracranial biomechanics following cortical contusion in live rats

Non-ideal effects in indentation testing of soft tissues

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