title: Beware: Recruitment of Muscle Activity by the EEG-Neurofeedback Trainings of High Frequencies.
abstract: EEG-neurofeedback (NFB) became a very popular method aimed at improving cognitive and behavioral performance. However, the EMG frequency spectrum overlies the higher EEG oscillations and the NFB trainings focusing on these frequencies is hindered by the problem of EMG load in the information fed back to the subjects. In such a complex signal, it is highly probable that the most controllable component will form the basis for operant conditioning. This might cause different effects in the case of various training protocols and therefore needs to be carefully assessed before designing training protocols and algorithms. In the current experiment a group of healthy adults (n= 14) was trained by professional trainers to up-regulate their beta1 (15-22 Hz) band for eight sessions. The control group (n= 18) underwent the same training regime but without rewards for increasing beta. In half of the participants trained to up-regulate beta1 band (n= 7) a systematic increase in tonic EMG activity was identified offline, implying that muscle activity became a foundation for reinforcement in the trainings. The remaining participants did not present any specific increase of the trained beta1 band amplitude. The training was perceived effective by both trainers and the trainees in all groups. These results indicate the necessity of proper control of muscle activity as a requirement for the genuine EEG-NFB training, especially in protocols that do not aim at the participants' relaxation. The specificity of the information fed back to the participants should be of highest interest to all therapists and researchers, as it might irreversibly alter the results of the training.
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology of Polish Academy of Science Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Paluch
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology of Polish Academy of Science Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Jurewicz
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology of Polish Academy of Science Warsaw, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Rogala
authors.affiliation: Centre for Physical Education and Sport, Military University of Technology Warsaw, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Krauz
authors.affiliation: Department of Physical Education, University of Physical Education Warsaw, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Szczypińska
authors.affiliation: Department of Physical Education, University of Physical Education Warsaw, Poland.
authors.forename: Mirosław
authors.initials: M
authors.lastname: Mikicin
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology of Polish Academy of Science Warsaw, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Wróbel
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology of Polish Academy of Science Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kublik
keywords: artifacts; attention; beta rhythm; biofeedback; muscle control; placebo