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