research methods. methods of visualizing the living human brain - structure contrast x-rays –...

Research Methods

Methods of Visualizing the Living Human Brain - Structure

Contrast X-Rays – inject something that absorbs X-rays

Cerebral angiography

Computed Tomography (CT Scan) cross sectional images

CT SCAN When:

Find cause of symptoms (confusion, vision problems, headaches, paralysis)

Trauma Guidance for biopsy

What: bleeding in brain, clot, enlarged cavities, fractures, disease, tumors

Magnetic Resonance Imaging (MRI) Produces 3-D images with high spatial

resolution

http://www.med.harvard.edu/AANLIB/cases/caseNA/pb9.htm

Methods of Visualizing the Living Human Brain - Functional

Positron Emission Tomography (PET) Inject radioactive 2-DG

Functional MRI (fMRI) Visualizing oxygen flow in the

brain

fMRI Vs PET

1. Nothing injected.

2. Provides both structural and functional information in one image

3. Spatial resolution is better than with PET

4. Can create 3-D images of activity over the entire brain

Electroencephalgram (EEG) Measure overall brain activity Epilepsy Sleep Disorders Monitor Brain activity during anethesia

Invasive Physiological Research Methods

Animal research Stereotaxic surgery

Lesioning Electrical stimulation Invasive recording methods

Manipulating or measuring within the brain

Copyright © 2006 by Allyn and Bacon

Stereotaxic Surgery

Used to position experimental devices within the brain

Stereotaxic atlas – provides coordinates for locating structures within the brain

Bregma – a point on the top of the skull often used as a reference point

Sterotaxic instrument – used to hold head steady and guide the device to be inserted

Copyright © 2006 by Allyn and Bacon

Lesion Methods

Remove, damage, or destroy a part of the brain to observe impact on behavior

Types of lesions Aspiration lesions – suction Radio-frequency lesions (high frequency

current) – heat destroys tissue Knife cuts – may damage surrounding area

Used to eliminate conduction in a nerve or tract

Cognitive Neuroscience

Goal is to identify the parts of the brain that mediate various constituent cognitive processes

Paired-image subtraction technique – compare PET or fMRI images during several different cognitive tasks

Behavioral Paradigms

Procedures developed for the investigation of a particular behavioral phenomenon

Traditional conditioning paradigms Skinner boxes Mazes

Autopsies & Brain Damage