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fall 14 - me334 - mechanics of the brain
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me 334 - mechanics of the brain 14 ellen kuhl
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dissecting brains
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objectives
our brain is not only our softest, but also our least well-understood organ. floating in the cerebrospinal fluid, embedded in the skull, it is almost perfectly isolated from its mechanical environment. not surprisingly, most brain research focuses on the electrical rather than the mechanical characteristics of brain tissue. recent studies suggest though, that the mechanical environment plays an important role in modulating brain function. neuromechanics has traditionally focused on the extremely fast time scales associated with dynamic phenomena on the order of milliseconds. the prototype example is traumatic brain injury where extreme loading rates cause intracranial damage associated with a temporary or permanent loss of function. neurodevelopment, on the contrary, falls into the slow time scales associated with quasi-static phenomena on the order of months. a typical example is cortical folding, where compressive forces between gray and white matter induce surface buckling. to understand the role of mechanics in neuroanatomy and neuromorphology, we begin this course by dissecting mammalian brains and correlate our observations to neurophysiology. we discuss morphological abnormalities including lissencephaly and polymicrogyria and illustrate their morphological similarities with neurological disorders including schizophrenia and autism. then, we address the role of mechanics during brachycephaly, plagiocephaly, tumor growth, and hydrocephalus. last, we explore the mechanics of traumatic brain injury with special applications to shaken baby syndrome.
grading
- 20 % dissection - presentation and written report, 10% each
- 30 % homework - three homework assignments, 10% each
- 20 % project presentation - graded by the class
- 30 % project report - graded by instructor
syllabus
| day | date | topic | slides | homework | |
|---|---|---|---|---|---|
| tue | sep | 23 | introduction to brain anatomy | s01 | |
| thu | sep | 25 | introduction to brain mechanics | s02 | |
| tue | sep | 30 | dissecting brains | s03 | |
| thu | oct | 02 | brain anatomy - student presentations | s04 | |
| tue | oct | 07 | brain mechanics in 1d – elasticity of neurons | s05 | |
| thu | oct | 09 | brain growth in 1d – growth of axons | s06 | |
| tue | oct | 14 | brain growth in 2d – morphogenesis | s07 | |
| thu | oct | 16 | brain growth in 3d – evolution and development | s08 | |
| tue | oct | 21 | brain growth in 3d – physiology and pathology | s09 | |
| thu | oct | 23 | brain mechanics in 3d – elasticity of the brain | s10 | |
| tue | oct | 28 | brain mechanics in 3d – viscoelasticity and multiple sclerosis | s11 | |
| thu | oct | 30 | brain mechanics in 3d – viscoelasticity and aging | s12 | |
| tue | nov | 04 | brain tumor growth in 3d – brain tumors | s13 | |
| thu | nov | 06 | brain tumor growth in 3d – brain tumors | s14 | |
| tue | nov | 11 | brain surgery - craniosynostosis and intracranial pressure | s15 | |
| thu | nov | 13 | brain surgery - brain tumors and craniosynostosis | s16 | |
| tue | nov | 18 | brain dynamics in 1d - diffuse axonal injury | s17 | |
| thu | nov | 20 | brain dynamics in 3d – traumatic brain injury, shaken baby syndrome | s18 | |
| tue | dec | 02 | final projects - discussion, presentation, evaluation | s19 | |
| thu | dec | 04 | final projects - discussion, presentation, evaluation | s20 | |
| fri | dec | 05 | final project reports due |
matlab files
here's the matlab code for brain folding
additional reading
bayly pv, taber la, kroenke cd.
mechanical forces in cerebral cortical folding: a review of measurements and models.
j mech beh biomed mat. 2014;29:568-581.
(download)
budday s, steinmann p, kuhl e. the role of mechanics during brain development.
j mech phys solids. 2014:72:75-92.
(download)
budday s, raybaud c, kuhl e.
a mechanical model predicts morphological abnormalities in the developing human brain.
scientific reports. 2014;4:5644.
(download)
budday s, nay r, steinmann p, wyrobek t, ovaert tc, kuhl e.
mechanical properties of gray and white matter brain tissue by indentation.
submitted for publication. 2014.
(download)
dennerll tj, lamoureux p, buxbaum re, heidemann sr.
the cytomechanics of axonal elongation and retraction.
j cell bio. 1989;109:3073-3083.
(download)
franceschini g, bigoni d, regitnig p, holzapfel ga.
brain tissue deforms similar to filled elastomers and follows consolidation theory.
j mech phys solids. 2006;54:2592-2620.
(download)
hardan ay, libove ra, keshavan ms, melhem nm, minshew nj.
a preliminary longitudinal magnetic resonance imaging study of brain volume and cortical thickness in autism.
biol psych. 2009;66:320-326.
(download)
kruse sa, rose gh, glaser kj, manduca a, felmlee jp, jack cr, ehman rl.
magentic resonance elastography of the brain.
neuroimage. 2008;39:231-237.
(download)
miller k, chinzei k.
constitutive modelling of brain tissue: experiment and theory.
j biomech. 1997;30:1115-1121.
(download)
raybaud c, widjaja e.
development and dysgenesis of the cerebral cortex: malformations of cortical development.
neuroimag clin n am. 2011;21:483–543.
(download)
richman dp, stewart rm, hutchinson jw, caviness vs.
mechanical model of brain convolutional development.
science. 1975;189:18-21.
(download)
sun t, hevner rf.
growth and folding of the mammalian cerebral cortex: from molecules to malformations.
nature neurosci. 2014;15:217-231.
(download)
van essen dc.
a tension-based theory of morphogenesis and compact wiring in the central nervous system.
nature. 1997;385:313-318.
(download)