Recording EEG during fMRI

The Instrument Development Lab is currently testing and developing a system to allow simultaneous recording of EEG during fMRI for the detection of seizures. Normal amplifiers and electronics can not perform in the extremely harsh environment of the magnet room. This system consists of a preamplifier that is optically coupled via fiber optic cable to an amplifier outside the magnet room. The signal is further amplified and converted back into an electrical signal. This electrical signal can then be acquired and processed by standard data acquisition equipment.

Small preamplifier sits just outside magnet bore. The design and construction of the cirucitry is kept as small as possible to reduce the amount of electrical noise. EEG signals from carbon electrodes are amplified and converted into a light signal. The fiber optic cable passes out of the magnet room and into another amplifier.

The incoming light signal is further amplified and converted to an electrical signal, which can be aquired by a computer with a data aquisition card.

  • Red - Metal Electrode, Grass Amplifier
  • Blue - Carbon Electrode, Grass Amplier
  • Black- Metal Electrode, Optical Amplifier
  • Green- Carbon Electrode, Optical Amplifier

Comparison between a Grass Model 15 Neurodata Amplifier system and the optical system show faithful reproduction of the signal through 50' of fiber optic cable with no noticable loss in signal quality. Seizure activity can clearly be seen by the high frequency spiking.

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