Several functional imaging techniques are now available which provide the possibility to look non-invasively inside the brain in vivo and to study human brain function. Magnetoencephalography is one such functional brain imaging technique, which is truly non-invasive and allows the localization of the electrical activity of nerve cells within the brain with a few mm accuracy and fast time resolution (~1 msec).
The magnetic field generated by intracellular currents from an individual neuron is extremely small, too small to be detected outside the head. In fact, several thousand synchronously active neurons are needed to generate the field measured by the MEG. The magnetic fields being measured from the brain are in the range of 50-1000 femtotelsa (fT), which is an extremely weak signal and is about one billion times smaller than the earth's magnetic field. The MEG technique has very sophisticated instrumentation sensitive enough to detect these weak signals, while simultaneously discriminating against interference from strong background noise.
- On the day of your test, you may have regular meals, and please follow your physician’s instructions regarding your medication.
- NO caffeine, alcohol, or nicotine the day before or the day of your test.
- Unless absolutely necessary, please turn off any implanted stimulator approximately four hours prior to scan.
- Wear comfortable clothing; you will not need to change for this test.
- Plan on being with us for 2 hours.
- When you arrive to the center, you will be greeted by the Clinical Research Coordinator, and asked to fill out an extensive questionnaire.
- Magnetic objects interfere with the MEG measurements, so you will be asked to remove all metal items, such as jewelry, watch, belt, hair pins, hearing aids, underwire bra, and dentures.
- To keep track of the position of your head during the MEG recording, three small markers will be placed on your head. One will be just in front of each ear and one will be between your eyebrows.
- During the MEG recording, you will be seated and the MEG system will be placed close to your head (see picture).
- The MEG system is located in a magnetically shielded room. The door will be close during the recording