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Biological Psychology: Research Methods
Dr. Katherine Mickley Steinmetz
Outline
� Neuroscience Methods � Histology � Electrophysiological
Recordings � Lesion � Neuroimaging
Neuroanatomy � Histology:
� Brain structure � Brain organization � Connections
Neurotracers
� Autoradiography � inject radioactive substance � allow uptake by neurons and transport throughout the
dendrites and axons (24-72 hrs) � Slice brain and develop radioactive substance
Neuroanatomy � Immunocytochemistry – uses the immune antibody
system to label any cellular component � Can label neurotransmitters, enzymes, receptors, types of cells
(particular neurons, glial cells, etc.) � Can even measure neural activity - c-fos - a protein produced in
neuron’s soma following excitation
Outline
� Neuroscience Methods � Histology � Electrophysiological
Recordings � Lesion � Neuroimaging
Electrophysiological Recordings � Nerve Recordings - whole nerve, single fiber
� Whole nerve are integrated to show overall activity level in response to stimuli
� Single unit can analysis individual action potential response to stimuli
NaCl HCl
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Outline
� Neuroscience Methods � Histology � Electrophysiological
Recordings � Lesion � Neuroimaging
� What is a lesion?
� What can it tell us?
Neuropsychological Approach
Logic:
If a region of the brain is essential for some aspect,
Then damage to that region should affect performance on that aspect
** So neuropsychological approaches can tell us about the NECESSITY of a region for a particular function
� What are the pros and cons to naturally occurring lesions in humans?
Techniques for Studying Brain Function
� Ablation/Lesion � Stereotaxic
apparatus - accurate access to brain areas
� Stereotaxic atlas - map used to locate structures
Transcranial Magnetic Stimulation
clip
TMS Video
http://www.youtube.com/watch?v=XJtNPqCj-iA
Introduction to Biological Psychology
� Neuroscience Methods � Histology � Electrophysiological
Recordings � Lesion � Neuroimaging
Neuroimaging Approaches
� SPECT: single photon emission computed tomography
� CT (CAT): computed (axial) tomography
� PET: positron emission topography
� fMRI: functional magnetic resonance imaging
� ERP: event-related potentials
PET!(Positron Emission Tomography)"
• Small dose of a chemical (radionuclide) used to label glucose is injected into patient. "
• The radionuclide emits positrons. "
• A PET scanner will rotate around a patient's head to detect the positron emissions given off by the radionuclide. "
PET!(Positron Emission Tomography)!
!
• Can be used to examine brain function"• brain regions will uptake more of the labeled glucose when active during a cognitive task"
• The computer then uses the measurements of glucose utilization to produce a picture which is color coded."
PET!(Positron Emission Tomography)!
"
• “resting” in scanner (no task)
PET!(Positron Emission Tomography)!
"
• reading words
PET!(Positron Emission Tomography)!
"
• trying to remember words for a later memory test
PET!(Positron Emission Tomography)!
"
• must perform tasks in blocks of at least 30 sec
• cannot sort by performance (e.g., words that are later remembered vs. words that are later forgotten)
rest read rest remember rest read rest
(f)MRI: (functional) magnetic resonance imaging
MRI (Magnetic Resonance Imaging)
� Radio waves 10,000-30,000 times stronger than the magnetic field of the earth are sent through the body.
� This affects the body's atoms, forcing the nuclei to align to the magnetic field.
� As they move back into random position, they send out radio waves of their own, measured by the scanner.
� fMRI measures the signals emitted by oxygenated and deoxygenated blood
functional MRI!(Magnetic Resonance Imaging)!
Subtractive Logic � Most of the brain is active during most events
� We want to isolate regions that are specific to a task � So, construct 2 conditions that you believe have just
some crucial interesting difference � Treat one as baseline and subtract it from the other, to
get rid of all the activity the 2 conditions have in common
-
+
+
fMRI vs PET � Measures magnetic
properties of blood (deoxyhemoglobin)
� no radiation
� temporal resolution = 2-3 seconds
� spatial resolution = 2-3mm
� trials can be blocked/randomized
� Measures glucose uptake
� radiation
� temporal resolution = 30 seconds
� spatial resolution = 5-6mm
� trials can only be blocked
True of both: – poor temporal (time) resolution (seconds) – results dependent on task and baseline (subtractive
logic + pure-insertion problem) – Indirect measures of neural activity
Non-invasive Functional Neural Activity Measurements
� Low spatial resolution, high temporal resolution
• Event Related Potentials: average of many EEG stimulus presentations reduces variability
ERP: event-related potentials � advantages:
� excellent temporal resolution � you can know when something happened down to the
msec! � event-related neural responses � Direct measure of neural activity
� disadvantages: � poor spatial resolution
� You might not know exactly what part of the brain the activity is coming from
Group Activity � Hypothesis: Orbitofrontal cortex is not critical for learning
face-name pairs.
� What technique would be best to test this hypothesis? (behavioral study? Neuroimaging? Lesion studies? Other methods?)
� What result would support this hypothesis? Reject it?
� What factors would you need to control for?