Brain Imaging Techniques

Question 1

Computerized Axial Tomography (CAT/CT)

Answer 1

Uses x-ray energy to generate images (less safe than MRI)

Useful for visualizing problems such as strokes, tumors, cortical shrinkage

Series of ~20 2D X-ray images stacked into 3D image

STRUCTURAL

Question 2

Magnetic Resonance Imaging (MRI)

Answer 2

Uses magnetic fields and radio waves to create map of tissue density

Fewer damaging effects than CT, higher resolution images, but expensive and relatively time consuming

Magnet causes protons in tissues to line up parallel then they are knocked over by radio waves. When the radio pulse is turned off, protons relax at different speed, emitting radio waves that are measured by detectors surrounding the head

STRUCTURAL

Question 3

Functional MRI (fMRI)

Answer 3

Generates images of brain activity rather than structure

Uses rapidly oscillating magnetic fields to detect blood oxygenation and flow in most active parts of brain (measures brain metabolism)

“Difference images”- show specific activity of different parts of brain during different experimental activities

FUNCTIONAL

Question 4

Positron Emission Tomography (PET)

Answer 4

Inject radioactive isotopes into bloodstream, it is then pumped into active regions of brain, radiation detectors create color-coded brain use map

FUNCTIONAL

Question 5

Transcranial Magnetic Stimulation (TMS)

Answer 5

Focal magnetic currents stimulate cortex, allows stimulation of discrete area and resulting behavior

FUNCTIONAL

Question 6

Magnetoencephalography (MEG)

Answer 6

Ultra sensitive detectors measure magnetic activity from cortical neurons

Real-time maps of brain activity during ongoing cognitive processing

FUNCTIONAL

Question 7

Electroencephalography (EEG)

Answer 7

Measures electrical activity from neurons

FUNCTIONAL

Question 8

Diffusion Tensor Imaging (DTI)

Answer 8

Measures directional flow of water in axons

Trace axon pathways in living brain