Transcript RESEARCH METHODS IN BIOPSYCHOLOGY

RESEARCH METHODS IN
BIOPSYCHOLOGY
LECTURE NOTES
Based on Pinel, Chapter 5
METHODS TO STUDY THE NERVOUS
SYSTEM
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Brain Imaging & Brain Stimulation
Techniques in Living Humans
Psychophysiological Techniques
Invasive Physiological Methods
Neuropharmacological Methods
Genetic Engineering
BEHAVIORAL METHODS IN
BIOPSYCHOLOGY
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Neuropsychological Testing
Behavioral Methods in Cognitive
Neuroscience
Animal Behavior Paradigms
IMAGING & STIMULATING THE
LIVING BRAIN
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Contrast X-rays
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cerebral angiography
Computed Tomography (CT)
Magnetic Resonance Imaging (MRI)
Positron Emission Tomography (PET)
Functional MRI (fMRI)
Magnetoencephalography (MEG)
Transcranial Magnetic Stimulation (TMS)
CT SCANS
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A computer assisted X-ray
procedure
An X-ray scanner is rotated
1o at a time over 180 o
Computer reconstruction
Horizontal sections
Reveal structural
abnormalities, such as
cortical atrophy or lesions
caused by a stroke or
trauma.
MRI SCANS
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A strong magnetic field causes
hydrogen atoms to align in the
same orientation.
When a radio frequency wave
is passed through the head,
atomic nuclei emit
electromagnetic energy.
The MRI scanner is tuned to
detect radiation emitted from
the hydrogen molecules.
Computer reconstructs image.
MRI VS. CT SCANS
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Advantages of MRI
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No ionizing radiation exposure
Better spatial resolution
Horizontal, Frontal or Sagittal planes
Disadvantages
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Cost
No ferrous metal!
PET SCANS
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A positron emitting radionuclide is
injected (e.g., 2-deoxyglucose).
Positrons interact with electrons
which produce photons (gamma rays)
traveling in opposite directions.
PET scanner detects the photons.
Computer determines how many
gamma rays from a particular region
and a map is made showing areas of
high to low activity.
PET Versus CAT
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CAT scans show brain structures.
PET scans reveal brain activity.
CAT involves absorption of X-rays.
PET involves emission of radiation
by an injected or inhaled isotope.
FUNCTIONAL MRI
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Images brain hemodynamics.
Advantages over PET:
– No injections need to be
given
– Structure and Function
– Shorter imaging time
– Better spatial resolution
– 3-D images
Check out this website for more info on fMRI
methods: http://www.fmri.org/fmri.htm
Magnetoencephalography (MEG)
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MEG measures changes in magnetic fields on the
scalp surface that are produced by changes in
patterns of neural activity.
Advantage over fMRI
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Advantage over EEG
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faster temporal resolution
greater accuracy and more reliable localization due to
minimal distortion of the signal
Clinical Uses
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Evaluation of epilepsy: to localize the source of epileptiform
brain activity, usually performed with simultaneous EEG
Transcranial Magnetic Stimulation
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TMS disrupts neural activity by creating a
magnetic field under a coil positioned near
the skull.
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Disruption of specific cortical locations are
produced while participants engage in cognitive
and/or behavioral tasks.
This allows researchers to assess functions of
specific cortical areas.
PSYCHOPHYSIOLOGY
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Electroencephalography
(EEG)
Electromyography (EMG)
Electrooculography (EOG)
Electrodermal activity (Skin
Conductance)
Cardiovascular activity
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Heart rate (EKG)
Blood Pressure
Plethysmography
INVASIVE PHYSIOLOGICAL METHODS
IN NONHUMANS
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Stereotaxic Surgery
Lesion Methods
Electrical Stimulation
Electrophysiological
Recording
LESIONING TECHNIQUES
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Aspiration lesions
Radio-frequency lesions
Knife cuts
Cryogenic blockade
Chemical Lesions
NEUROHISTOLOGY TECHNIQUES
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Fixation, preservation of tissue,
sectioning and staining of tissue
Uses of histological techniques
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Confirming lesion sites or electrode
locations
In combination with neural tracing
techniques (anterograde,
retrograde labeling)
In combination with
autoradiography or
immunohistochemistry techniques
NEUROHISTOLOGICAL STAINING
TECHNIQUES
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Nissl Stains
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Golgi Silver Stain
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e.g., cresyl violet
stains mainly cell bodies
stains whole neurons
Myelin Stains (Fiber stains)
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e.g., Weigert stain
stains mainly myelin
For more information on neurohistological stains, visit:
http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab9/Lab9.htm
Brain images obtained from
http://www.brainmuseum.org
ELECTROPHYSIOLOGY TECHNIQUES
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Intracellular unit
recording
Extracellular unit
recording
Multiple-unit recording
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See page 114 in Pinel
NEUROPHARMACOLOGICAL METHODS
Measuring Chemical Activity in the Brain
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2-DG Autoradiography
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Radioactive 2-deoxyglucose is injected
Animal engages in behavior of interest
Animal is euthanized, brain tissue is removed and sliced
Tissue slices are coated with photographic emulsion and
stored in the dark (much like film processing)
Areas that absorbed high levels of radioactive substance
will appear darker
Using computer imaging, differences in density can be color
coded.
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e.g., see page 115 in Pinel
NEUROPHARMACOLOGICAL METHODS
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Cerebral Dialysis (in vivo microdialysis)
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Under anesthesia and stereotaxic guidance, a cannula is
inserted into a specific brain site.
Following recovery, a small probe with a semipermeable
membrane is inserted into the cannula.
Fluid is perfused through the probe and chemicals in the
extracellular fluid diffuse across the membrane and are
collected into a sample vial.
The samples are then analyzed using a chromatography
methods. (e.g. HPLC)
NEUROPHARMACOLOGICAL METHODS
Localizing Neurotransmitters and Receptors
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Immunocytochemistry
– Makes use of antibodies for specific proteins, such as receptors or
enzymes.
– The antibody is labeled with a fluorescent die or a radioactive element
(commercially available).
– Brain tissue is sliced and exposed to a solution containing the labeled
antibody.
– Brain slices are viewed under microscope to identify the regions where
protein of interest is distributed.
In situ hybridization
– Also used to locate peptides or proteins in tissue
– Hybrid strands of mRNA are artificially created and labeled with a dye
or radioactive element
– Brain tissue slices are exposed to solution containing the labeled
mRNA
– Brain slices are viewed under microscope to identify regions where the
mRNA expression is highest
 e.g., see page 117 in Pinel
GENETIC ENGINEERING
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Gene Knockout Techniques
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Creating organisms lacking certain genes
Limitations regarding interpretation of knockout effects
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Most behavioral traits are influenced by the activities of multiple genes
Elimination of a gene may modify the expression of other genes
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Effects of gene knockout may be masked by compensatory changes to
other genes
Experience influences gene expression, so effects of knockout may
interact with experience in complex ways
Gene Replacement Techniques
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Creating transgenic organisms
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e.g. inserting human genetic material into mice
ANIMAL BEHAVIOR PARADIGMS
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Species-common behaviors
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Aggressive Behaviors
Defensive Behaviors (e.g., anxiety paradigms)
Reproductive Behaviors
Locomotor Activity
Traditional Conditioning Paradigms
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Pavlovian (Classical) Conditioning
Operant Conditioning
ANIMAL BEHAVIOR PARADIGMS
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Common Learning Paradigms
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Conditioned Taste Aversion
Conditioned Escape/Avoidance
Conditioned Place Preference
Radial Arm Maze
Morris Water Maze
Operant Conditioning Apparatus
Conditioned Place Preference
Apparatus
Radial Arm Maze
Open Field Apparatus