Research Methods in Biopsychology

RESEARCH METHODS IN BIOPSYCHOLOGY

LECTURE NOTES
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
o 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
o No ionizing radiation exposure
o Better spatial resolution
o Horizontal, Frontal or Sagittal planes
* Disadvantages
o Cost
o 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:
o No injections need to be given
o Structure and Function
o Shorter imaging time
o Better spatial resolution
o 3-D images

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
o faster temporal resolution
* Advantage over EEG
o greater accuracy and more reliable localization due to minimal distortion of the signal
* Clinical Uses
o 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.
o Disruption of specific cortical locations are produced while participants engage in cognitive and/or behavioral tasks.
o This allows researchers to assess functions of specific cortical areas.

PSYCHOPHYSIOLOGY
* Electroencephalography (EEG)
* Electromyography (EMG)
* Electrooculography (EOG)
* Electrodermal activity (Skin Conductance)
* Cardiovascular activity
o Heart rate (EKG)
o Blood Pressure
o 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
o Confirming lesion sites or electrode locations
o In combination with neural tracing techniques (anterograde, retrograde labeling)
o In combination with autoradiography or immunohistochemistry techniques

NEUROHISTOLOGICAL STAINING TECHNIQUES
* Nissl Stains
o e.g., cresyl violet
o stains mainly cell bodies
* Golgi Silver Stain
o stains whole neurons
* Myelin Stains (Fiber stains)
o e.g., Weigert stain
o stains mainly myelin

ELECTROPHYSIOLOGY TECHNIQUES

* Intracellular unit recording
* Extracellular unit recording
* Multiple-unit recording
o See page 114 in Pinel

NEUROPHARMACOLOGICAL METHODS Measuring Chemical Activity in the Brain

* 2-DG Autoradiography
o Radioactive 2-deoxyglucose is injected
o Animal engages in behavior of interest
o Animal is euthanized, brain tissue is removed and sliced
o Tissue slices are coated with photographic emulsion and stored in the dark (much like film processing)
o Areas that absorbed high levels of radioactive substance will appear darker
o Using computer imaging, differences in density can be color coded.
+ e.g., see page 115 in Pinel
* Cerebral Dialysis (in vivo microdialysis)
o Under anesthesia and stereotaxic guidance, a cannula is inserted into a specific brain site.
o Following recovery, a small probe with a semipermeable membrane is inserted into the cannula.
o Fluid is perfused through the probe and chemicals in the extracellular fluid diffuse across the membrane and are collected into a sample vial.
o The samples are then analyzed using a chromatography methods. (e.g. HPLC)

NEUROPHARMACOLOGICAL METHODS
Localizing Neurotransmitters and Receptors

* Immunocytochemistry
o Makes use of antibodies for specific proteins, such as receptors or enzymes.
o The antibody is labeled with a fluorescent die or a radioactive element (commercially available).
o Brain tissue is sliced and exposed to a solution containing the labeled antibody.
o Brain slices are viewed under microscope to identify the regions where protein of interest is distributed.
* In situ hybridization
o Also used to locate peptides or proteins in tissue
o Hybrid strands of mRNA are artificially created and labeled with a dye or radioactive element
o Brain tissue slices are exposed to solution containing the labeled mRNA
o Brain slices are viewed under microscope to identify regions where the mRNA expression is highest
+ e.g., see page 117 in Pinel

GENETIC ENGINEERING
ANIMAL BEHAVIOR PARADIGMS

RESEARCH METHODS IN BIOPSYCHOLOGY.ppt