Cherish Madu
This wiki explores the methods that those interested in neuroscience most frequently employ when investigating and explaining cognitive processes in terms of brain structure and function and highlights the advantages and disadvantages of each method.
Transcranial Magnetic Stimulation
Overview, Advantages, Disadvantages
Optogenetics
Overview, Advantages, Disadvantages
Electrophysiological recording of neurons
Overview, Advantages, Disadvantages
Electroencephalography
Overview, Advantages, Disadvantages
Positron Emission Tomography
Overview
Positron emission tomography (PET) is a three-dimensional brain imaging technique that takes advantage of changes in metabolism to localize brain activity and functional processes in the body. The most active parts of the brain use more metabolic processes than do relatively inactive parts of the brain and PET is able to track this metabolic flow. Flourine-18 or oxygen-15, the most commonly used radioactive tracer isotopes, is injected into the bloodstream where it disperses to more active parts of the brain. Inside the brain, the radioactive tracer decays into a positron and an electron. When the positron collides with an electron, two gammas rays are produced. The accumulation of these pairs of gamma rays is measured by gamma-ray detectors which are placed all around the subject's head. Computer analyses construct the radioactive tracer concentration into three-dimensional images. PET is often combined with CT or MRI scans for superimposition of the images of concentration onto anatomic images of the subject's brain.
PET is not only used in neuroimaging. It also has applications in oncology and pharmacology. Flourodeoxyglucose (FDG) is primarily used in oncology because of its ability to track glucose metabolism in cancer tissues.
Advantages
High Spatial resolution
Disadvantages
Because the positron has to travel before it collides with an electron to produce gamma-rays, temporal resolution is low. It takes time for the concentration of gamma-rays to accumulate into a reliable signal. Invasive. Injection of radioactive molecules
Functional Magnetic Resonance Imaging
Like PET, Functional magnetic resonance imaging (fMRI)