¥ Between OLSQ and GLSQ+REML:
H Individual subject thresholded activation maps may differ very little, some, or a lot
¥ Level of temporal correlation determines how much difference
GLSQ makes to individual subject statistics
H Amount of
temporal correlation seems to depend on magnetic field strength, other scanner details, pulse sequence, É
H Effect of
temporal correlation also seems to depend on stimulus timing
H As theory
indicates:
o Temporal correlation means
noise variance depends on frequency
o So amount of noise that interferes with (Òlooks likeÓ) the
signal will depend on frequencies at which the
hemodynamic response is appreciable
¥ Next slides: Group activation maps, GLSQ+REML vs OLSQ
H 2 cases
from NIH: Event-related and Block:30s designs
H DonÕt have
enough FBIRN-1 subjects to do a group analysis