PSY 200 Lecture Notes - Lecture 38: Multiple Sclerosis, Hemoglobin, Block Design
Document Summary
Huntington"s caused by an inherited defect in a single gene. How does an fmri differ from an mri? fmri studies brain function, whereas, mri studies brain anatomy. Mri computes one image, fmri computes many images taken over time. Mri is high resolution, fmri is lower resolution. Localized change in neural activity increase in oxygen consumption and blood flow decrease in deoxyhemoglobin more uniform local magnetic field = increase in mr signal. Run a continuous block of same cognitive state for 16-40 secs, average across interval. Because block design takes so long, its specificity is decreased, making event-related design more accurate. A unit used to make up 3d images provided by an fmri scan (like a 3d pixel) fmri preprocessing state. Why: data are noisy, subjects move, things change. Motion correction, superimpose functional images onto anatomical images. Brain activation levels must always be considered relative to another condition. The absolute level of signal is relatively meaningless on its own.
