Chapter Four: Neurons, Hormones, and the Brain

Mapping the Brain

INTRODUCTION

The brain's structure and function can be studied by observing patients with brain damage, leisioning brain sections in animals, or using techniques that monitor the activity of the brain.

WHAT'S AHEAD

• Why are patterns of electrical activity in the brain called "brain waves"?
• What two techniques allow psychologists to view changes in the brain while people listen to music or solve math problems?

KEY CONCEPTS

Mapping the Brain

EEG
PET
MRI

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Mapping the Brain [p.125]

INTRODUCTION

Don't try this at home!!!

KEY CONCEPTS EXPLAINED

.Damaged Brains

A person's behavior may have been altered because of brain disease or injury. Locating the damaged area may tell us something about how that part of the brain is suppose to function by observing what has happened when it is damaged.

.Lesion Method

Systematically damaging sections of brains in animals and observing their effects on behavior.

.Monitoring Activity in the Brain

...Electrodes

• Electrodes, needle electrodes, and microelectrodes can be used to measure electrical activity of neurons (i.e. the neurons firing [ rewind]).
  
  
• Brain Waves: Machine translates the electrical activity signals into wavy lines on a moving piece of paper.

...Electroencephalogram (EEG)

Detects electrical activity of a large number of neurons.

...Positron-Emission Tomography (PET Scan)

• records biochemical changes.
  
  
• radioactive glucose accumulates in brain areas that are active and consuming glucose.
  
  
• shows which parts of the brain are active during different mental activities.
  
  
• can diagnose psychological abnormalities if areas are too active or underactive.

...Magnetic Resonance Imaging (MRI)

• The vibrations of the nuclei of the atoms making up an organ are monitored by special receivers which convert signals into a high contrast picture of the brain.
  
  
• Can identify the structures of the brain. In combination with other techniques, MRI can also provide information about brain function.

Different Ways of Mapping the Same Area of the Brain

PET Scan	MRI
Function	Structure
wwwlink for more comparisons between the PET and MRI: The Monkey Image Data Set.

GLOSSARY

		electroencephalogram (EEG)
		PET scan (positron emission tomography)
		MRI (magnetic resonance imaging)

LINKS About Brain Mapping

• wwwlink: Everything you ever wanted to know about a PET Scan.
• wwwlink:How PET works - Shockwave Format -- Very Good
• wwwlink: MRI Tutorial
• wwwlink: VOXEL-MAN Junior Project: A QuickTime VR view of the brain. (Big file but fun to play around with VR technology)
• wwwlink Movies of the Visible Human Project Brain.

Next Topic - A Tour Through the Brain.....................................Chapter Contents