Transcript Computerized Tomography

Brain Imaging
Techniques
Phrenology
Figure 2.1 A wrongheaded theory
Myers: Psychology, Eighth Edition
Copyright © 2007 by Worth Publishers
X-Ray Transmission Imaging
Shoot x-rays through the
patient onto detector film.
Different tissues absorb
and deflect x-rays to
different degrees. The
film is exposed less when
x-rays encounter higher
density material like bone.
Low resolution. Hard to
distinguish between blood
vessels and tissue without
an injection of iodine or
barium
Electroencephalography
Electrodes on the scalp record
electrical activity
Each electrode provides a signal
from a particular region
The electrode can then provide
unique electrical activity in that
region
Figure 2.12 An electroencephalograph providing amplified tracings of waves of electrical activity in the brain
Myers: Psychology, Eighth Edition
Copyright © 2007 by Worth Publishers
Computerized Tomography
Imaging of a cross sectional
slice of the body using Xrays.
Invented by Dr. G. N.
Housfield in 1971. Received
the Nobel prize in medicine
in 1979.
The method is constructing
images from large number
of measurements of x-ray
transmission through the
patient.
Computerized Tomography
Example of cross-sections through several parts of the
body: skull, thorax, and abdomen,
obtained by computed tomography.
Magnetic resonance imaging (MRI)
Magnetic resonance imaging exploits
the existence of induced nuclear
magnetism in the patient.
Magnets with an odd number of
photons or neutrons possess a
weak but observable nuclear
magnetic moment
MR images provide
excellent contrast
between various
forms of soft
tissues.
Planes of Image
Acquired
Coronal
Horizontal
Sagital
Brain section
Spinal cord
Positron Emission Tomography
Positron emission tomography measures cerebral
glucose metabolism, using a radioactive tracker/
marker of neuronal activity (usually radioactive
glucose or even oxygen)
Measures the amount of glucose present in general
locations of the brain, shows relative activity levels
Not very clear resolutions, only shows general areas
Whole body PET
Functional MRI
fMRI is a technique that images intrinsic blood signal change with magnetic
Resonance imagers.
Changes in neuronal activity are accompanied by focal changes in cerebral
blood flow (CBF), blood volume (CBV), blood oxygenation and metabolism.
These physiological changes can be used to produce
functional maps of mental operations.
Figure 2.28 New technology shows
the brain in action
Myers: Psychology, Eighth Edition
Copyright © 2007 by Worth Publishers
Figure 2.20 The hypothalamus
Myers: Psychology, Eighth
Edition
Copyright © 2007 by Worth
Publishers
Lesion
Electrical Stimulation
(Open-brain surgery)
Case Study