Re: Event Related Potentials

From: Sharples Karen (
Date: Wed May 22 1996 - 13:15:17 BST

The principle use of Event Related Potentials (ERP) is to determine the
time course of higher level processes in the human brain. ERP's occur
as small fluctuations in Electroencephalogram (EEG) recordings in
response to the presentation of a single stimulus, either sensory,
motor or a mental event, eg the participant maybe asked to add two and
two together. On an EEG recording these event related fluctuations
maybe difficult to detect as they are often masked by electrical
signals generated by other unrelated brain activity. To 'unmask' the
true ERP it is necessary to take recordings from repeated presentations
of the stimulus in order for a computer to produce an averaged, much
clearer ERP wave form. By measuring the time it takes for an ERP to
occur after presentation of the stimulus, and by taking recordings from
several areas of the brain, it is possible to determine the sequence
and timing of the specific areas activated within the brain. These
results are often analysised in accordance with visual images taken of
the brain during presentation of the stimulus, eg through PET scans.
The results of these studies, more often than not, are conclusive with
those of the ERP recordings. Areas of higher mental processing that
have already been, (and still are being), investigated using this
technique include perception and attention.

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