Functional Neuroimaging

Question 1

what is the BOLD signal? MRI detects Hb in which of its forms?

Answer 1

blood oxygen level dependent signal for fMRI

deoxygenated- the influx of much more oxyHb changes the local magnetic properties

Question 2

describe the effects of additive stimuli as it relates to BOLD response

Answer 2

3 identical stimuli yields a 3x higher BOLD response, but after 5+ stimuli, the brain reaches steady state due to physiological limits in how much O2 rich blood can be shunted to a given brain area

Question 3

how can fMRI inform behavior?

Answer 3

1. mapping specific regions in
   cognition
2. mapping brain NETWORKS which subserve cognition
3. modeling individual differences

Question 4

what are network-based analyses derived from?

Answer 4

FUNCTIONAL CONNECTIVITY, or correlated activity among brain regions

Question 5

a clinical measure that reliably activates the dorsal (and lesser extent, ventral) visual networks

Answer 5

the judgment of line orientation test

Question 6

how does recruitment of the dorsal visual network correlate with performance? what does this mean?

Answer 6

negatively correlates; high performers do not draw upon this network as strongly as poor performers

Question 7

how does PET work?

Answer 7

CYCLOTRON particle accelerator bombards atoms with protons to create RADIONUCLIDES (unstable isotopes)

RADIOTRACERS; emits two gamma particles in opposite directions, PET scanner uses a circular detector to determine origin of gamma particles

Question 8

radionuclide and how it works molecularly

Answer 8

fluoro-2-deoxy-D-glucose (FDG) gets phosphorylated, and ‘STUCK’ inside tissues, prevents glycolysis; decay occurs it becomes heavy O2 and glycolysis occurs

Question 9

why FDG?

Answer 9

QUANTITATIVE, ABSOLUTE measure of metabolism unlike fMRI

Question 10

what is FDG/PET scans useful for detecting?

Answer 10

oncology, epileptogenic foci

Question 11

this transporter may predict cocaine sensitivity, Parkinson’s risk

Answer 11

dopamine transport receptors

Question 12

virtually identical to PET, but less expensive, longer-lived,

Answer 12

single photon emission computed tomography (SPECT)

Question 13

clinical relevance of neuroimaging

Answer 13

1. presurgical mapping of language and memory function for hippocampectomy or surgical resection
2. major depressive disorder, showing altered function of networks (mood regulation and mood monitoring)

Question 14

functional neuroimaging shows this part of the brain to be linked with major depressive disorder

Answer 14

cingulate (linked to treatment non-response), targeted for stimulation

Question 15

PET shows baseline major depressive disorder activity of this part of the brain can predict treatment response

Answer 15

insula

Question 16

PTSD is associated with greater response in these areas, and diminished response in these areas..

Answer 16

greater anterior cingulate and amygdala response

diminished prefrontal responses

Question 17

fMRI compared to PET

Answer 17

non invasive, greater temporal resolution, slightly better spatial resolution, pet gives absolute measure (Glu metabolism), fmri gives relative measure (% BOLD)

Question 18

fMRI compared to EEG

Answer 18

fmri much better spatial resolution, MUCH worse temporal resolution (seconds vs milliseconds)