PSYC 3270 Lecture Notes - Lecture 3: Visual Cortex, Voxel, Proceedings Of The National Academy Of Sciences Of The United States Of America

• School: University of Guelph
• Department: Psychology
• Course: PSYC 3270
• Professor: Naseem Al- Aidroos

Document Summary

Activity leads to local increase in oxygenated hemoglobin: hemodynamic response peaks around 6-8s, limiting temporal resolution of fmri. Oxygenated (hb) and deoxygenated hemoglobin (dhb) have different magnetic properties: changes in hb:dhb ration can be imaged, changes in bold (i. e. , from decrease in oxygenation level, or change in blood flow) Motion (any small amount of motion can change voxel data) Drift (in the magnetic field over time) Distortions (e. g. , our eyes create scan distortions) Hemodynamic response (hrd: changes in bold over time in response to cognitive events (change in blood flow in relation to change in cerebral activity) Initial dip once you shine light in the eyes (since it uses some oxygen), Overcompensation once the oxygen is concentrated in that cerebral area. Graph indicates 10 minutes of activity within one voxel. Straight lines indicate changes in the experimental condition (cognitive state of the subject) Challenging to detect hdr because bold signals overlap over time.