A second linked-reference issue: possible biasing of power and coherence spectra

The effect of a linked-ears reference on scalp-recorded potentials was investigated in six subjects during an eyes-closed counting task. EEG was recorded from the midline and surrounding electrodes with a linked-ears reference, and from Fz, Cz, and Pz with an active reference three cms anterior (clo...

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Bibliographic Details
Published inInternational journal of neuroscience Vol. 75; no. 1-2; p. 111
Main Author Travis, F
Format Journal Article
LanguageEnglish
Published England 1994
Subjects
Adult
Ear - physiology
Electroencephalography - standards
Evoked Potentials - physiology
Female
Humans
Male
Mental Processes - physiology
Reference Values
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Summary:The effect of a linked-ears reference on scalp-recorded potentials was investigated in six subjects during an eyes-closed counting task. EEG was recorded from the midline and surrounding electrodes with a linked-ears reference, and from Fz, Cz, and Pz with an active reference three cms anterior (close-bipolar). The linked-ears data were also converted to current source densities by applying the Laplacian. Coherence and power spectra were calculated for the three data sets. Linked-ears frontal relative power was significantly higher than current source density or close-bipolar power at 7-Hz--the frequency of peak parietal power. Also, the linked-ears coherence spectrum was significantly higher than current source density or close-bipolar coherence spectra, and tended to have a smaller range of values. These data replicate and extend earlier reports of distortion of coherence spectra by a common reference.
ISSN:0020-7454
DOI:10.3109/00207459408986294