Induced activity

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The term induced activity is used in electroencephalography and magnetoencephalography for certain types of stimulus-related activity. The following explanation is for electroencephalographic activity, but the concept is the same in magnetoencephalography.

Evoked potentials and event-related potentials are obtained from the electroencephalogram by stimulus-locked averaging. As a consequence, those signal components that are the same in each single measurement are conserved and all others average out. This is the wanted effect to eliminate the ongoing brain activity. But there might also be signals that are related to stimulus processing, but are different each time. An example is oscillatory activity (e.g. gamma oscillations), which might have a different phase in each single measurement and therefore would cancel out during averaging. This type of electroencephalographic activity is called induced activity.