Download - Neurobiology of Everyday Life Final Project
Understanding the Brain: The Neurobiology of
Everday Life
Diffusion Tensor Imaging Use in Stroke Patients to Predict Motor Outcome
For the Neurobiology of Everyday Life Coursera MOOC, I would like to share some research on my Masters project in Biomedical Engineering
and how this coures helped me understand the biological processes behind what I study.
Diffusion Tensor Imaging
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Non-DiffusionWeighted
Diffusion-WeightedMany Directions
Diffusion Tensor forEvery Voxel
Diffusion Weighted Imaging is a Magnetic Resonance Imaging technique that allows one to look at the diffusion of water in the brain.
The process consists of taking 1 or 2 “non-diffusion weighted images” to which one compares many “diffusion-weighted images”. This allows the computation of a “diffusion matrix”, which characterizes the direction of and magnitude of water diffusion in different parts of the brain.
Neurons
Beaulieu, C. 2002
Myelinated Axon
Brain TissueFree Diffusion Strongest
in Direction of Axon
Healthy Neurons
Why do we care about water diffusion in the brain ?
Water diffusion strength and direction is determined by the orientation of axons and degree of myelination !
By looking at diffusion of water in the brain, we can obtain information about the integrity of axons and neurons
Myelinated Axon
Brain TissueFree Diffusion Strongest
in Direction of Axon
Beaulieu, C. 2002
Damaged Neurons
When axons are damaged, for example, by stroke, degradation of internal structures makes water diffusion in the direction of the axon decrease
Also, because the myelin sheet and axonal membrane will eventually degrade, diffusion perpendicular to the axon will increase
Neurons
Stroke
Neuroscience, 2nd Ed., Purves, D. 2001
The artery that is most commonly affected by stroke is the middle cerebral artery which vascularizes the white matter tracts of the corticospinal tract as well as the basal ganglia, which are critical to movement of the upper and lower limbs !
My Project
Clinical Neuroanatomy & Neuroscience, 6th Ed., FitzGerald, MJ et al., 2012
I share with you an aspect of my Masters thesis: to look at how the integrity of axons change in response to ischemic stroke by looking at the diffusion of water in the axons.
By looking at the severity of the damage at early time points through “Diffusion Tensor Imaging”, we hope to be able to predict by how much a person can recover upper or lower limb strength months after stroke onset.
Parts of Nervous System Involved
Cellular Structures (Axonal Membrane, Myelin)
Axons
Cortical Spinal Tract
Here, the cellular components of the neurons in the cortical spinal tract are impaired by ischemic stroke, resulting in a decrease in motor strength, and dexterity of the upper and lower limbs
Objectives of the Study
The Neurobiology of Everyday Life has helped me understand my Masters project in several ways.
My undergraduate background was in physics and engineering, so the technological aspects of Magnetic Resonance Imaging and Diffusion Tensor Imaging are more familiar to me. I am therefore less proficient in the neurobiology of motor output and neuronal damage.
This course has helped me to bridge the gap between physics, engineering and neuroscience. I now understand better the biological origin of the signals we are measuring in MRI in our patient database and how to relate them to future motor outcome.
Above all, this course allows me to broaden my perspectives on how brain imaging techniques (such as MRI and DTI) can be used to study other pathologies by knowing their biological mechanisms and properties
References Internship
THANK YOU !
References Internship
Beaulieu, C. (2002). The basis of anisotropic water diffusion in the nervous system - a technical review. NMR in Biomedicine, 15(7-8), 435–55. doi:10.1002/nbm.782
Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001.
M. J. T. FitzGerald MD PhD DSC MRIA, Gregory Gruener MD MBA. Clinical Neuroanatomy and Neuroscience. 6th edition. Saunders; 2012