Download Methods of Studying the Brain

Methods of Studying the Brain
Mrs. Joseph
AP Psychology
Solon High School
Clinical Observation
• Study effects of accidents/brain damage
(oldest way of studying)
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Strokes
Traumatic Injury
Tumor
Lesion
Clinical Observation
Phineas
Gage
Frontal lobotomy
Electrical Stimulation
Note effect of weak electrical currents on behavior
Can be used on humans or animals
Electroencephalograph (EEG)
Electrodes measure electrical waves sweeping across surface of
the brain
EEG (Electroencephalography)
• Technique: Multiple electrodes are pasted to
outside of head
• What it shows: A single line that charts the
summated electrical fields resulting from the
activity of billions of neurons
EEG (Electroencephalogram)
• Advantages
– Detects very rapid changes in electrical activity,
allowing analysis of stages of cognitive activity
• Disadvantages
– Provides poor spatial resolution of source of
electrical activity
Brain Scans
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CAT (or CT Scan)
MRI
PET
fMRI
CAT (CT) Scan
Computerized Axial Tomography
Cross-section X-ray pictures of the brain
Can reveal brain damage
MRI
Magnetic Resonance Imaging
• Aligns atoms in brain, then disorients them, measures
detectable signals as they move back into place
• Gives detailed picture of soft tissues
MRI (Magnetic Resonance Imaging)
• Technique: Exposes the brain
to magnetic field and measures
radio
frequency waves
• What it shows: Traditional MRI
provides high resolution image
of brain anatomy, and newer
functional images of changes in
blood flow (which indicate
specific changes in neuronal
activity)
Advantages of MRI
• Requires no exposure to radioactivity
• Provides high spatial resolution of anatomical
details (<1 mm)
• Provides high temporal resolution (<1/10 of a
second)
PET Scan
Positron Emission Tomography
PET (Positron Emission Tomography)
SPECT (Single Photon Emission Computed Tomography)
• Technique: Positrons and
photons are emissions from
radioactive substances
• What it shows: An image of the
amount and localization of any
molecules that can be injected
in radioactive form, such as
neurotransmitters, drugs,
tracers for blood flow or
glucose use (which indicates
specific changes in neuronal
activity)
PET Scan
PET (Positron Emission Tomography)
SPECT (Single Photon Emission Computed Tomography)
• Advantages
– Allows functional and biochemical studies
– Provides visual image corresponding to anatomy
– Can identify specific receptors or transporters associated
with some neurotransmitters
• Disadvantages
– Requires exposure to low levels of radioactivity
– Provides spatial resolution better than that of EEG, but
poorer than that of MRI
– Cannot follow rapid changes (faster than 30 seconds)
fMRI
Functional MRI
fMRI (functional Magnetic Resonance
Imaging)
• Technique: uses paramagnetic
properties of oxygenated and
deoxygenated hemoglobin to
see images of changing blood
flow in the brain associated
with neural activity
• What it shows: brain
structures and processes
associated with perception,
thought and action
Advantages and Disadvantages of
fMRI
• Advantages
– Better resolution than PET scans
– Extremely sensitive to changes in blood flow, so
can detect even small changes in the brain
(stroke)
– No exposure to radioactivity (PET)
• Disadvantages
• Can identify specific receptors or transporters associated with
some neurotransmitters