The modulation of alpha-wave amplitude in human EEG by the intention to act with a motor response

The most conspicuous signal in the human EEG is the so-called alpha wave, oscillations in the frequency range of 8 to 12 Hz. Visual stimulation of the retina suppresses the amplitude of alpha waves (Berger effect), and increased attention can reduce them. Here I show that one more parameter significantly affects the amplitudes of alpha waves: the intention to act by a motor response. Together with data from the literature, these results show that alpha waves are not part of the visual processing network but rather part of a long-range neuromodulatory network. The modulation modifies latencies in perception or motor response. The relevant mechanisms are located in early cortical visual areas; their activity may contribute to hemodynamic changes in these areas and thus explain dissociations between _Bold_ signals and spike activities mentioned in the literature

Non-adiabatic extension of the Zak phase and charge pumping in the Rice--Mele model

In this study, the Landau--Zener (LZ) transition method is applied to investigate a weak non-adiabatic effect on the Zak phase and the topological charge pumping in the Rice--Mele model. The non-adiabatic effect is formulated using the LZ transfer matrix. The effective lower band wave function picks up the Stokes phase as well as the usual dynamical phase through two avoided crossings appearing in the two band instantaneous energy spectrum. The interference effect from the upper band has a decisive influence on the decay behavior of the lower band population. A non-adiabatic extension of the Zak phase can then be formulated, corresponding to the center of mass of the lower band Wannier function. Furthermore, we estimate the validity of the LZ formalism and verify the breakdown of the quantization of the topological charge pumping by changing the sweeping speed.Comment: 8 pages, 4 figures, accepted in EPJ