The contingent negative variation (CNV), and the associated
event-related desynchronization (ERD) on motor areas and sensory areas, and
increase of alpha in the ipsilateral to the cued stimulus side, are different brain
signals that reflect motor, sensory, and cognitive activations related to the
expectancy of the next stimulus. However, the possibility of an overall change
in EEG oscillatory activity during expectancy periods has not been directly
addressed. The present report tests whether the background oscillatory
activity is modulated by a warning signal. During the expectancy period, the
power spectral density (PSD) between 0 and 42.9 Hz – including delta, theta,
alpha, beta, and gamma – decreased with respect to the baseline. These results
suggest that during expectancy periods there is a generalised decrease in the
oscillatory activity, and that reduction of the EEG power would facilitate the
phasic and oscillatory neural activities triggered by the next target stimulus.Junta de AndalucíaMinisterio de Ciencia y Tecnología (España
