This essay stresses that the ongoing electroencephalogram (EEG) provides a satisfactory scale for accessing temporal evolution of the brain activity associated with cognitive processes in health and disease. However, momentary changes in brain activity, as reflected in EEG, are rarely exploited due to lack of analytical tools and methodology. The electrodes covering the parietal lobe typically measure the P300 signal most strongly. The presence, magnitude, topography and time of this signal are often used as metrics of cognitive function in decision-making processes. While the neural substrates of this ERP remain hazy, the reproducibility of this signal makes it a common choice for psychological tests in both the clinic and the laboratory.
This paper declares that the EEG signal is most strongly acquired around the parietal electrodes, interactions involving the frontal and temporal regions as well as several deep brain loci have been suggested. These components respond individually to different stimuli, and it has been suggested that the P300 originates from stimulus-driven frontal attention mechanisms during task processing. The P300 signal is an aggregate recording from a great many neurons In practice, the P300 waveform must be evoked using a stimulus delivered by one of the sensory modalities. One typical procedure is the 'oddball' paradigm, whereby a target stimulus is presented amongst more frequent standard background stimuli. A distracter stimulus may also be used to ensure that the response is due to the target rather than the change from a background pattern. ...Show more