Induced alpha band power changes in the human EEG and attention.
Induced alpha power (in a lower, intermediate and upper band) which is deprived from evoked electroencephalograph (EEG) activity was analyzed in an oddball task in which a warning signal (WS) preceded a target or non-target. The lower band, reflecting phasic alertness, desynchronizes only in response to the WS and target. The intermediate band, reflecting expectancy, desynchronizes about 1 s before a target or non-target appears. Upper alpha desynchronizes only after a target is presented and, thus, reflects the performance of the task which was to count the targets. Thus, only slower alpha frequencies reflect attentional demands such as alertness and expectancy.
Klimesch
W
W
Department of Physiological Psychology, University of Salzburg, Austria. wolfgang.klimesch@sbg.ac.at
Doppelmayr
M
M
Russegger
H
H
Pachinger
T
T
Schwaiger
J
J
D000328:Adult; D000513:Alpha Rhythm; D001288:Attention / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time