Ongoing brain activity

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The term ongoing brain activity is used in electroencephalography and magnetoencephalography for those signal components that are not associated with the processing of a stimulus or the occurrence of specific other events, such as moving a body part, i.e. that do not form evoked potentials/evoked fields, event-related potentials, or Induced activity. The ongoing activity is usually considered to be noise if one is interested in stimulus processing, but might be informative regarding the current mental state of the person (e.g. wakefulness, alertness) and is often used in sleep research. Certain types of oscillatory activity, such as alpha waves, are part of the ongoing activity.

The ongoing electroencephalogram (EEG) and magnetoencephalogram (MEG) provide a satisfactory scale for accessing temporal evolution of the brain activity associated with cognitive processes in health and disease. However, momentary (temporal) changes in brain activity, as reflected in EEG/MEG, are rarely exploited due to lack of analytical tools and methodology. Special techniques such as microstructural EEG/MEG analyses (see the review by Fingelkurts An.A., Fingelkurts Al.A., and Kähkönen S. New Perspectives in Pharmaco-Electroencephalography. Progress in Neuro-Psychopharmacology and Biological Psychiatry. 2005, 29(2):193-199) are required for the detection of such dynamics.