S183. The dynamics of the m. extensor digitorum communis cortical representation after motor imagery training sessions using brain-computer interface: Controlled study

Abstract

Introduction Mechanisms of goal oriented movements in human arm are not clearly understood. Cortex reorganization after motor learning is of special interest. nTMS is widely used in the field of research related to mechanisms of movement on the cortical level. Mental practice with motor imagery (MI) paradigm is noted for its ability to activate motor system-related areas and to cause neuroplastic changes in cortical motor organization. Brain computer interfaces are used to enhance mental practice providing appropriate feedback in the form of robotic or exoskeleton external devices. Methods The aim of our study was to investigate the reorganization of cortical motor representation of extensor digitorum communis muscle after motor imagery training course enhanced by noninvasive EEG-based brain-computer interface (BCI) with exoskeleton of the hand in healthy subjects. In the current study thirty-four healthy subjects (nine of them were left-handed) were enrolled and randomized into main and control group. Every volunteer completed 10 training sessions of BCI-enhanced motor imagery. Mapping of m. extensor digitorum communis of dominant hand cortical motor representation with the evaluation of area, weighted area and the location of centers of gravity using self-designed program software was performed before and after 10 training sessions. Cortical representation areas were visualised using spherical Voronoi tessellation. Results No significant differences in the amplitude of motor thresholds (MT in rest 57.71 and 54.18, p > 0.05, MT during MI 53.06 and 51.76, p > 0.05), cortical motor representation area and weighted area were seen in both groups before intervention (371.227 and 468.719 mm2, p > 0.05; 102461.066 and 133264.876 mm2 × uV, p > 0.05). One way ANOVA test revealed no significant change in parameters of cortical motor representations in the main group comparing to control after intervention (centers of gravity displacement F = 0.360, p = 0.553, area of cortical motor representation of m.extensor digitorum communis F = 3.599, p = 0.068; weighted area F = 1.522, p = 0.227). Conclusion No significant differences in nTMS parameters of cortical motor representation of target muscle were shown between main and control group. This data could be partly explained by extremely high interindividual variability of TMS parameters, limited sample size and limitations of methodology. Futher research is needed. Funding is provided by grant RFBR N 16-04-01766.