PSYCH 160A Lecture Notes - Lecture 6: Functional Magnetic Resonance Imaging, Pulse Oximetry, White Matter
25 Jan 2020
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Document Summary
Images of white matter axon fibers. Characterizes the integrity of large-scale neural networks. Has been most helpful in disease populations and in studies of aging. Tracks changes brain activity through it"s corresponding changed in blood oxygen levels over time. Neuronal activity and blood oxygenation levels are yoked. Blood with and without oxygen have different magnetic properties. Can be identified with fmri & other imaging techniques. All blood-based responses (including fmri) are slow. Not measuring individual action potentials, or even single cognitive events. The signals are also not particularly big. ~. 01 2% change in signal as compared to baseline. Combat these problems using sophisticated experimental design and statistics. Blocked designs: pack lots of trials together and compare brain activity on two tasks. Many more: repetition suppression, pattern classification, functional connectivity. Note: a few millimeters of cortex contains over 100,000 neurons. Whole brain imaging: don"t have to pre-select where to measure.
