Chapter 5

visualizing human brain

100

Methods for Visualizing the Living Human Brain (structural)

what is 

CT Scan (computed tomography)

MRI (magnetic resonance imaging) 

DTI (diffusion tensor imaging)

200

Methods for Visualizing the Living Human Brain (functional)

What is

PET (positron emission tomography)

F-MRI (functional- MRI)

MEG (magneto encephalography)

TMS (transcranial magnetic stimulation)

EEG (electro encephalography)

ERP’s (event related brain potentials)

300

CT Scan

what is (computed tomography) 

• uses x-rays
• measures density of tissue

400

MRI  

What is (magnetic resonance imaging)

• Large; strong magnet
• Takes very detailed structural images
• Measures waves of hydrogen atoms make when they are moved by radio frequency pulse

500

DTI

What is (diffusion tensor imaging)

• Uses MRI magnet
• Measures diffusion of water
• Purpose: map axons
• Axons are covered in myelin; water can’t diffuse through myelin because it’s fatty; axons are everywhere water can’t diffuse

visualizing human brain cont.

100

PET

What is (positron emission tomography)

• Inject person with radioactive glucose
• then do taks
• whatever neurons active during task will “eat” the glucose
• scan to see where radioactivity is

200

F-MRI

What is (functional- MRI)

• Uses MRI machine
• Measures/imaging effects of oxygen
• When neurons become active while doing a task, they use al the oxygen nearby and call out for more blood
• Takes 7 seconds for oxygenated blood to arrive
• f-mri measures this stage of O2 blood

300

Advantages of using F-MRI over PET:

What is

• Nothing radioactive is injected
• More detailed images

400

MEG

What is (magneto encephalography)

• Only 20 in U.S.
• Active neurons generate an electrical current
• Perpendicular to electrical current = magnetic field
• Measures magnetic fields produced by your active neurons from surface of your head

500

TMS

What is (transcranial magnetic stimulation)

• Uses wand with coil that generates magnetic field
• This MF stimulates neurons below the skull
• Low setting: stimulates neurons; used for therapy
• High setting: stops neurons from firing; used for research

visualizing human brain/ testing

100

EEG

What is (electro encephalography)

• Recording of electrical activity from the surface of the scalp
• Summed activity of many groups of neurons
• Recorded with electrodes
• Used to diagnose epilepsy, sleep disorders
• Great for timing, poor for location

200

ERP’s

What is (event related brain potentials)

• EEG that is time locked to a stimuli
• Much “cleaner” than EEG
• Brains response to certain type of stimuli
• Different components of ERP are sensitive to different sensory/ cognitive processes

300

Other electrical activity recorded on the body

What is

• Muscle tension (EMG-electromyography)
• Eye movements (EOG-electrooculography)
• Skin Conductance (SCR)  

400

Categories of Invasive Research Methods:

What is 

1. Electrical stimulation

• (Humans and animals)

2. Lesion Methods 

• Aspiration, radio frequency (heat), Cuts, cryogenic blocks (reversible)

3. Invasive Recording

• Intracranial EEG (Both humans and animals)
• Single unit recording (animals only)

4. Locating Neurotransmitters

• Immunocytochemistry, in situ hybridization
• (both humans and animals, post- mortem)

500

Tests of Speech Lateralization:

What is

• Wada test (sodium amytal): dye injected to visualize blood vessels to test for language/memory
• Dichotic listening test: If left dominant = you will repeat numbers you heard in right ear first

testing

100

Assessment of Frontal Lobe

what is

 Wisconsin card sorting test

• measures person's ability to think flexibility and adapt to change in rules

200

Default mode network

What is 

• Network of brain areas = active when NOT involved in task; thinking about yourself; remembering past; planning future
• See decrease in activity during task, increase when no task