Functional Magnetic Resonance Imaging is another popular tool used by neuroscientists. It uses a large magnet (one capable of producing a magnetic field approximately 50,000 times that of earth’s magnetic field) to measure the amount of oxygen in different parts of the brain. Scientists can then infer how much activity is taking place in theses areas based on the oxygen levels.

This technique has become popular for a number of reasons. It is easy for the experimenter to use and requires no injections or radiation so the risk to the subject is minimal. The results of this scan provide researchers with descent temporal resolution as well as descent spacial resolution, but aren’t perfect. There is a delay between the presentation of a stimuli and the measured response since blood flow is not instantaneous. They are also limited as to how small of a difference they can detect. MRI’s have yet to get down as small as the neuron level. One other draw back is the noise produced by the machine. The loud “wurring” can potential distract a subject or cause them to feel uncomfortable which could throw off the results.

The different colors indicate different levels of oxygen in the brain which can be equated to different levels of neural activity.

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