Week 5.1 fMRI Flashcards
what does an fMRI measure
changes associated with blood flow, the assumption that cerebral blood flow and neuronal activation are coupled
what is the BOLD principle
this is how you map the neural activity in the brain and spinal cord. This is blood-oxygen-level dependent, and accounts for the hemodynamic response.
why is BOLD the preferred method
because no injection or implementation
what is true of blood with a higher oxygen content
that more O2 is susceptible to magnetic responses, so it shows up more
neural activity is associated with
increased blood flow
what happens to brain after activation
there is a 2 second post activation lighting up, and then it peaks at 4-6 seconds.
when was the BOLD method created, and what is it correlated to
1990s and EEG/MEG
how does an fMRI work
same as MRI, for alignment. With a stable magnetic field
what is used to deflect
RF pulses, and you visualize differences between arterial and venous blood, and oxygen saturation
what is a voxel
three dimensional rectangular area of the brain that is 1-5mm depending on the size of the scan
average, 1 voxel equals ___ neurons and ____ synapses
few million neurons and 10s of billions of synapses
what is the timecourse
the response to signal over time, or the activity in the voxel
colors are the
activated voxels
what are the criticisms of fMRI
there is a high rate of noise, due to head movements, and decreased neural activity from doing to the same thing, or getting bored.
what did scanning a dead salmon show us
that there is still areas of the brain that will light up, even in a dead salmon
