BCS 242 Lecture Notes - Lecture 19: Parietal Lobe, Diffusion Mri, Tractography
7 Dec 2016
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Document Summary
Arcuate fasciculus: voxel: smallest unit in brain that can be measured, bold signal: blood oxygen level dependence signal brain activity, subtraction method: comparing bold signals between conditions (eg. , left hand activity v. right hand) Functional connectivity: time course of activation in certain voxels compared to others correlation of bold signal over time. Diffusion mri: different kinds of tissue have unique anisotropy (being directionally dependent: doesn"t work well in gray matter because it is isotropic, anisotropic voxels are directionally dependent. Tractography (dti: green: anterior posterior, blue: superior inferior, red: lateral medial, deterministic tractography: assumes single fiber orientation in each voxel. However, can have hundreds of neurons in one voxel. Hard to assume single directionality of one single voxel: probabilistic tractography: assumes a distribution of possible fiber orientations within voxel. Posterior: geschwind wernicke: probabilistic tractography can detect what deterministic can"t. Neuropsych evaluation: aphasia: spontaneous speech, sentence repetition, verbal fluency. Semantic processing, lexical retrieval: apraxia: function, manipulation knowledge for objects.
