Unformatted text preview: blood in his system.”
-- William James, Principles of Psychology (1890) Positron Emission Tomography (PET)!
Tracks blood ﬂow in the brain by
monitoring the distribution of a
radioactive tracer that is injected into
the blood stream.!
In the 1960s and 1970s we begin to see more advanced
tecniques. The basic idea is that the subject is injected w/ a
radio-active isotope and the half life is ~90 secs, and the
scanner (positron) is able to pick up the e- being emitted from
the isotopes, thus they collide and form Gamma rays and are
able to triagonize exactly where these Gamma rays came
from. Go through the process again but this time they are
reading words.. And they can pick up the difference by
contrasting the brain states. Thus more active when reading
the word. Quite successful technique, but the disadvantage is
that it is slightly invasive and fussy anatomy. Functional Magnetic Resonance Imaging (fMRI)!
“MRI is based on the detection of electromagnetic signals (radio frequency (RF) waves)
which emanate from spinning hydrogen protons when they are excited by an RF pulse
applied in the presence of an externally generated static magnetic ﬁeld.” (DeYoe, 1994).! Functional Magnetic Resonance Imaging (fMRI)!
MRI: anatomical fMRI: functional
(~3 mm but can be better)
many images high resolution (1 mm)
one image MRI
different tissues have different
magnetic susceptibilities Overcame many of the problems of past
techniques; can look at the anatomy and the...
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- Fall '11
- Magnetic resonance imaging, Functional magnetic resonance, neural activity, BOLD Signal, Functional magnetic resonance imaging