Anxiety and synchrony of alpha oscillations.

The associations between state anxiety and individually adjusted alpha sub-bands mean spectral power and coherence measures registered in resting condition and during experimental settings were investigated in 30 males aged 18-25 years. Averaged across all cortical sites, spectral power was treated as a complex measure dependent on both the number of active alpha oscillators and the degree of their synchrony. Averaged across all electrode pairs, squared coherence was treated as a global measure of alpha synchrony. The relationship between state anxiety and baseline alpha power was mostly mediated by alpha synchrony. During transition through experimental settings, the dynamics of alpha2 and alpha3 power was mostly accounted for by changes of these sub-bands' synchrony. The synchrony-independent power component demonstrated linear trends implying that, during the experiment, the number of active alpha oscillators linearly decreased in subjects with low state anxiety and linearly increased in subjects with high state anxiety. These findings are discussed in terms of alpha synchronization as an active process, allowing dynamic regulation of alpha system preparedness for processing of external stimuli.