Flashcards in What can fMRI tell us about cognition? Deck (66)
why do neurons differ in length and size?
connect to different brain regions > further apart require longer neurons
receive messages from other cells =
electrical activity can be detected on the scalp using an _____
what is the function of fMRI?
how the brain is responding and where activity is generated in specific brain regions
why do we need to have an anatomical scan for each ppt?
everyone has a different brain structure
Oxygen is delivered to neurons in ________ in _______ RBCs
why do neurons need oxygen?
because they lose energy when they fire electrical signals > this needs to be replenished
why would a resting neuron show reduced blood flow?
doesn't need as much O2 as not firing
what does fMRI record?
blood flow towards activated areas of the brain
Hb is ________ when oxygenated and _______ when deoxygenated
does diamagnetic Hb or paramagnetic Hb have a stronger magnetic field?
diamagnetic > as is oxygenated!
what is the fMRI response to oxygen called?
the BOLD response
what does BOLD stand for?
Blood Oxygen Level Response
there is an initial ____ in haemodynamic blood flow followed by an _____ that overcompensates for the amount of oxygen used
when does the increase in oxygen to Hb start happening?
approx 4 seconds (quite slow)
what is the con associated with fMRI?
the delay between when we respond to a stimulus and when we can measure a response (low temporal resolution)
why is there a delay in measuring a response?
because we have to wait for the blood supply to be redirected to that area
what shows how magnetic the Hb is?
the MR signal
when does the MR signal peak in the BOLD response?
between 4 and 8s
too much O2 in the area once it is oxygenated (peak) then dissipates out and brings it back to normal levels =
what happens after the primary response?
a negative overshoot where area becomes slightly deoxygenated
what are the 3 planes that the brain can be viewed?
coronal (front), saggiato (side) and axial (down)
why might we combine EEG and fMRI?
they have complementary pros and cons which allows us to deepen our knowledge
which method has low temporal resolution but high spatial resolution?
which method has low spatial resolution but high temporal resolution?
give an example of where EEG and fMRI are combined
early visual processing
how we process visual stimuli and the immediate response =
early visual processing
what stimulus do we often use for EEG studies testing visual processing?
a robust response to a stimulus that shows a consistent change that happens repeatedly and shows a pattern =