Glossary Terms  Home

E

Echo-Planar Imaging (EPI)

A technique that allows collection of an entire two-dimensional image by changing spatial gradients rapidly following a single electromagnetic pulse from a transmitter coil.

Electroencephalography (EEG)

The measurement of the electrical potentional of the brain, usually through electrodes placed on the surface of the scalp.

Electromotive Force

A difference in electrical potential that can be used to drive a current through a circuit. the MR signal is the electromotive force caused by the changing magnetic field across the detector coil.

Epoch

A tim segment extracted from a larger series of images, usually corresponding to the period in time surrounding an event of interest.

Euler characteristic

The number of clusters of significant activity due to chance that can be expected based upon the number of resels and the smoothness of data.

Excitation

The process of sending electromagnetic energy to a sample at its resonant frequency (also called transmission). The application of an excitation pulse to a spin system causes some of the spins to change from a low-energy state to a high-energy state.

Experimental Factors

Model factors that are associated with specific experimental hypotheses.