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Unformatted text preview: ces takes 80 seconds.!
Extremely high spatial resolution! Echo Planar Imaging (EPI)!
One RF echoes back and forth through the plane.
One slice can be scanned in 40 ms, 25 slices can be
scanned in 2 seconds. !
Whole brain very quickly, but not as high spatial
resolution and not as stable.!
EPI is much less stable than conventional imaging, and not as ﬁne resolution. But the trade-off is worth it in
the end b/c can collect data very quickly. Physiological issues of the BOLD signal!
Physiological issues of the
Basic layout of how the
BOLD signal occurs. All
these areas have increased
in activity when they are
not… Physiological issues of the BOLD signal!
Sensitive, Motor, or Cognitive Task!
Localized increase in
Increased metabolic rate!
Increased Blood Volume!
(small compared to blood ﬂow)
! Increase in Blood ﬂow is
greater than the increase in
metabolism. This increase in
OC occurs in .5 sec and at
the same time there is an
increase in CBF, and thus
CBF will exceed the OC
increase. When the brain is
rest, there is still metabolism
and a baseline level of
increasing bloodﬂow and OC. Increased Blood Flow!
We are measuring at the
end the MR signal, so it is
a very indirect measure
of the n...
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This note was uploaded on 01/18/2014 for the course PSY 123 taught by Professor Staff during the Fall '11 term at UCSB.
- Fall '11