1. Saratov Branch, Kotel'nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Saratov, Russia.
2. Institute of Physics, Saratov State University, Saratov, Russia.
3. Donders Institute for Brain, Cognition and Behaviour, Donders Centre for Cognition, Radboud University, Nijmegen, The Netherlands.
4. Institute of Physiology I, University of Münster, Münster, Germany.