JHA410H1 Lecture Notes - Lecture 5: Cerebral Circulation, Motor Learning
Document Summary
Lecture 5: functional mri (fmri) fmri fmri measures brain activity by detecting changes associated with blood flow. Uses cerebral blood flow as a proxy for neuronal activation (i. e. when activity in an area of the brain increases, blood flow to that region also increases) Blood-oxygen-level dependent (bold) signal is the primary appraoch to fmri. Increase in neural activity needs both glucose and oxygen which are supplied by blood flow, therefore, increased nt activity requires increased energy demands. The bold signal is an indirect measure of this neural activity. Disadvantage of fmri is there is a delay between when neural activity starts and when bold signal changes (low temporal resolution) Deoxyhemoglobin is more sensitive to magnetic changes bc of its fe content compared to oxygenated hemoglobin. In the end the image produced uses a t2 sequence combined with changes in magentic field (i. e. bold signal) Example, going from deoxygenated to oxygenated increases bold signal and vice versa.
