Expected headings
"History and etymology"
"Blood flow in the brain is highly locally controlled in response to oxygen and carbon dioxide tension of cortical tissue. When a specific region of the cortex increases its activity in response to a task, the extraction fraction of oxygen from the local capillaries leads to an initial drop in oxygenated haemoglobin (oxyHb) and an increase in local carbon dioxide (CO2) and deoxygenated haemoglobin (deoxyHb). Following a lag of 2-6 seconds, cerebral blood flow (CBF) increases, delivering a surplus of oxygenated haemoglobin, washing away deoxyhaemoglobin 1,2. It is this large rebound in local tissue oxygenation which is imaged."
"There are a number of limitations of BOLD imaging (and all other techniques which image function by CBF):"