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

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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

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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)!

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•  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)!

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•  “resting” in scanner (no task)

PET!(Positron Emission Tomography)!

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•  reading words

PET!(Positron Emission Tomography)!

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•  trying to remember words for a later memory test

PET!(Positron Emission Tomography)!

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•  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

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+

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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?