Dynamic mechanical response of brain tissue in indentation in vivo, in situ and in vitro

Thibault P. Prevost, Guang Jin, Marc A. De Moya, Hasan B. Alam, Subra Suresh, Simona Socrate*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

79 Scopus citations

Abstract

Characterizing the dynamic mechanical properties of brain tissue is deemed important for developing a comprehensive knowledge of the mechanisms underlying brain injury. The results gathered to date on the tissue properties have been mostly obtained in vitro. Learning how these results might differ quantitatively from those encountered in vivo is a critical step towards the development of biofidelic brain models. The present study provides novel and unique experimental results on, and insights into, brain biorheology in vivo, in situ and in vitro, at large deformations, in the quasi-static and dynamic regimes. The nonlinear dynamic response of the cerebral cortex was measured in indentation on the exposed frontal and parietal lobes of anesthetized porcine subjects. Load-unload cycles were applied to the tissue surface at sinusoidal frequencies of 10, 1, 0.1 and 0.01 Hz. Ramp-relaxation tests were also conducted to assess the tissue viscoelastic behavior at longer times. After euthanasia, the indentation test sequences were repeated in situ on the exposed cortex maintained in its native configuration within the cranium. Mixed gray and white matter samples were subsequently excised from the superior cortex to be subjected to identical indentation test segments in vitro within 6-7 h post mortem. The main response features (e.g. nonlinearities, rate dependencies, hysteresis and conditioning) were measured and contrasted in vivo, in situ and in vitro. The indentation response was found to be significantly stiffer in situ than in vivo. The consistent, quantitative set of mechanical measurements thereby collected provides a preliminary experimental database, which may be used to support the development of constitutive models for the study of mechanically mediated pathways leading to traumatic brain injury.

Original languageEnglish (US)
Pages (from-to)4090-4101
Number of pages12
JournalActa Biomaterialia
Volume7
Issue number12
DOIs
StatePublished - Dec 2011
Externally publishedYes

Keywords

  • Brain indentation
  • Brain injury
  • Constitutive properties
  • Porcine
  • Viscoelasticity

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Biochemistry
  • Biomedical Engineering
  • Molecular Biology

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