78 0090-2977/17/4901-0078 © 2017 Springer Science+Business Media New York Neurophysiology, Vol. 49, No. 1, February, 2017 Features of EEG Activity Related to Realization of Cyclic Unimanual and Bimanual Hand Movements in Humans T. Tomiak, 1 A. V. Gorkovenko, 2 V. S. Mishchenko, 1 and D. A. Vasilenko 2 Received July 15, 2015 In 10 tested dextral subjects, EEG activity was recorded during the performance of unimanual and bimanual cyclic movements of the hands and fingers. The movements corresponded to clenching the fingers into a fist and the subsequent unclenching of the fingers. The test consisted of four successive stages, the resting state, movement of the left hand, that of the right hand, and movement of both hands. The dependences between the spectral power and coherence of the respective EEG samples on the type of the test performed, on the type of the movement (uni- or bimanual), and on the laterality of the latter in the case of the unimanual movement were examined. The results obtained allow us to propose the following conclusions: (i) α and β EEG rhythms are characterized by different functional importance with respect to manual motor activity; (ii) neural control of bimanual movements cannot be considered “a sum of the controls” of unimanual movements, and (iii) control of bimanual movements may be largely based on the control of the movement by a subdominant upper limb. Keywords: bimanual and unimanual movements, shoulder and elbow joints, EMG, EEG, spectral power, coherence, cyclic movements. 1 Academy of Physical Education and Sports, Gdansk, Poland 2 Bogomolets Institute of Physiology of the NAS of Ukraine, Kyiv, Ukraine. Correspondence should be addressed to A. V. Gorkovenko (e-mail: gork@biph.kiev.ua) INTRODUCTION Movements of the distal parts of the upper limbs constitute one of the most important components of the motor repertoire in humans. Functional organization of the mechanisms responsible for the control of uni- and bimanual movements still constitutes one of the crucial problems in modern neurophysiology. Studies of bimanual movements were based on examination of mechanical parameters of the limb motions [1], analysis of the muscle activity involved in their realization [2], and analysis of EEG activity related to these motor phenomena [3, 4]. There were also attempts to apply mathematical modeling for the analysis of CNS functions related to coordination of bimanual movements [5]. Elucidation of the questions of how the CNS coordinates movements of the two extremities in the case of bimanual performance and also of how the control of this movement is related to that of unimanual movements of the dominant and subdominant limb is believed to be specially important [6, 7]. Earlier, we examined the features of bimanual coordination in the course of performance of movements mimicking those in rowing [2]. In this work, we analyzed mechanograms of movements of oar “equivalents” and EMG activity of the respective muscles of both upper limbs. It should be noted that such a model of bimanual movements was probably rather simple from the aspect of central coordination (the subject in the course of testing should perform in-phase mirror-symmetrical movements) [8]. It is obvious that results of examination of mechanograms and activity of the limb muscles can help to understand the CNS mechanisms involved in the control of uni- and bimanual movements only to a limited extent. It can be expected that the research of activity of various cerebral structures with the use of the corresponding techniques may provide us with greater information in this respect. We used electroencephalography in such studies. Earlier, similar techniques were applied under conditions of temperature (cold) stimulation of the fingers [9] and in the performance of cyclic movements by the fingers of one hand [10]. Using EEG recording allows one to compare features of cortical activities related to bimanual movements and unimaual movements of the dominant and subdominant hand. Such an approach can open certain possibilities for better understanding of what are relations DOI 10.1007/s11062-017-9632-z