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RESEARCH METHODS IN BIOPSYCHOLOGY
LECTURE NOTES
Based on Pinel, Chapter 5
METHODS TO STUDY THE NERVOUS SYSTEM
Brain Imaging & Brain Stimulation Techniques in Living Humans
Psychophysiological Techniques Invasive Physiological Methods Neuropharmacological Methods Genetic Engineering
BEHAVIORAL METHODS IN BIOPSYCHOLOGY
Neuropsychological Testing Behavioral Methods in Cognitive
Neuroscience Animal Behavior Paradigms
IMAGING & STIMULATING THE LIVING BRAIN
Contrast X-rays – cerebral angiography
Computed Tomography (CT) Magnetic Resonance Imaging (MRI) Positron Emission Tomography (PET) Functional MRI (fMRI) Magnetoencephalography (MEG) Transcranial Magnetic Stimulation (TMS)
CT SCANS
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
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
Advantages of MRI – No ionizing radiation exposure– Better spatial resolution– Horizontal, Frontal or Sagittal planes
Disadvantages– Cost– No ferrous metal!
PET SCANS
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
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
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)
MEG measures changes in magnetic fields on the scalp surface that are produced by changes in patterns of neural activity.
Advantage over fMRI– faster temporal resolution
Advantage over EEG– greater accuracy and more reliable localization due to
minimal distortion of the signal Clinical Uses
– Evaluation of epilepsy: to localize the source of epileptiform brain activity, usually performed with simultaneous EEG
Transcranial Magnetic Stimulation
TMS disrupts neural activity by creating a magnetic field under a coil positioned near the skull.– 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
Electroencephalography (EEG)
Electromyography (EMG) Electrooculography (EOG) Electrodermal activity (Skin
Conductance) Cardiovascular activity
– Heart rate (EKG)– Blood Pressure– Plethysmography
INVASIVE PHYSIOLOGICAL METHODS IN NONHUMANS
Stereotaxic Surgery Lesion Methods Electrical Stimulation Electrophysiological
Recording
LESIONING TECHNIQUES
Aspiration lesions Radio-frequency lesions Knife cuts Cryogenic blockade Chemical Lesions
NEUROHISTOLOGY TECHNIQUES
Fixation, preservation of tissue, sectioning and staining of tissue
Uses of histological techniques– 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
Nissl Stains – e.g., cresyl violet– stains mainly cell bodies
Golgi Silver Stain– stains whole neurons
Myelin Stains (Fiber stains)– 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 fromhttp://www.brainmuseum.org
ELECTROPHYSIOLOGY TECHNIQUES
Intracellular unit recording
Extracellular unit recording
Multiple-unit recording– See page 114 in Pinel
NEUROPHARMACOLOGICAL METHODSMeasuring Chemical Activity in the Brain
2-DG Autoradiography– 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. e.g., see page 115 in Pinel
Cerebral Dialysis (in vivo microdialysis)– 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
NEUROPHARMACOLOGICAL METHODSLocalizing Neurotransmitters and Receptors
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
Gene Knockout Techniques– Creating organisms lacking certain genes– Limitations regarding interpretation of knockout effects
Most behavioral traits are influenced by the activities of multiple genes Elimination of a gene may modify the expression of other genes
– 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– Creating transgenic organisms
e.g. inserting human genetic material into mice
ANIMAL BEHAVIOR PARADIGMS
Species-common behaviors– Aggressive Behaviors– Defensive Behaviors (e.g., anxiety paradigms)– Reproductive Behaviors– Locomotor Activity
Traditional Conditioning Paradigms– Pavlovian (Classical) Conditioning– Operant Conditioning
ANIMAL BEHAVIOR PARADIGMS
Common Learning Paradigms– 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