Relationship between structural modeling and hyperelastic material behavior: application to CNS white matter

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Brain tissue material properties are crucial for understanding physiological and pathophysiological conditions.
• Microstructural analysis provides insight into the mechanical behavior of central nervous system (CNS) white matter.

Purpose of the Study:

• To establish a mathematical relationship between microstructurally based CNS white matter models and hyperelastic material models.
• To simplify the formulation by excluding time-dependent material behavior.

Main Methods:

• Formulating structural property relationships for highly oriented white matter using microstructural representations.
• Mathematically comparing these relationships to isotropic and anisotropic hyperelastic formulations.
• Assuming axonal alignment along a preferred direction for transversely isotropic characterizations.

Main Results:

• Anisotropic hyperelastic models with simple strain-energy functions can model nonlinear behavior predicted by structural models.
• Tangential stiffness in hyperelastic approaches does not perfectly match structurally based formulations.
• The study provides an initial link between tissue microstructure and large deformation material models.

Conclusions:

• This work is a foundational step in connecting microstructural properties of brain tissue to macroscopic material models.
• It facilitates relating predicted tissue deformation to cellular and subcellular structural deformation and stress.
• Further development may enhance understanding of brain tissue mechanics under various conditions.