FMRI Flashcards
how are fmri readings enhanced?
oxygen in the blood creates better readings
what is the name for oxygenated blood?
oxyhaemoglobin
what does bold stand for?
Blood oxygen level dependent
t or f, BOLD signals are an indirect measure of neruonal activity
true
what did ogawa find in 1990s
that large blood vessels cause brighter areas
what is statistical patametric mapping
fitting a general linear model to brain activity at each measurement point (voxel)
why does extraction rate go down when blood flow is faster?
because less oxygen is extracted per unit time
stefan delivering water bottle example
what is the temporal lag time between neural activity and BOLD response?
8 seconds
how long does BOLD signal take to go back to baseline?
around 16 seconds
3 limitations of BOLD fMRI
- temporal resolution (speed of readings)
- spatial resolution (how granular we can get) this is good - but not great 3x3x3 mm
- 50,000 t tests
- probably only looking at the tip of the iceberg
what is the bonferroni correction ?
divide the signifiance level by number of tests (voxels) and then new number is the p value that needs to be obtained on each test
issues with Bonferoni - correction?
we are probably overlooking stuff because we need such a conservative p value
