Spatio-temperal patterns of encephalographic signals during polyrythmic tapping

Interactions between limbs play an essential role in the formation of coherent macroscopic configurations during the bimanual performance of rhythmic movements. To uncover possible cortical aspects of these interactions, we study the relation between magneto-encephalographic signals and behavioral data during polyrhythmic tapping. In general, an explicit description of the relevant couplings requires a reliable quantification of phenomena like frequency and phase locking. Therefore, we first discuss a new cross-spectral measure that allows for the determination of frequency-locked areas in spatio-temporal signals. Subsequently, we estimate the corresponding generalized phase dynamics based on a system of two non-linearly coupled self-sustaining oscillators. The implications of these results for quantitative estimates of the functional coupling between hands/cortical areas in terms of distinct regimes of phase locking are discussed.