Figure 10.
Coupling of MEGSM1 with <3 Hz force fluctuations. A, Coherence between force and MEGSM1 signals (left), and between force and ∼20 Hz MEG SM1 envelope (right). Sub-blocks display the group-averaged coherence source map at 0.5–3 Hz (top) and the individual coherence spectra with the MEGSM1 signals. For indicative purpose, an orange dotted line indicates the significance level of the mean coherence across 0.5–3 Hz. B, Same as in A with the force replaced by its absolute change rate (|dF/dt|). C, D, Directional coupling quantified with renormalized partial directed coherence (rPDC). E, F, TRFs associated to force (E) and |dF/dt| (F) of <5 Hz MEGSM1 (left) and ∼20 Hz MEGSM1 envelope (right). The plots display individual TRFs (black traces) as well as the mean TRF across subjects (red trace) ±1 SEM (blue area) and ±2 SEM (cyan area). Note that we reversed the polarity of TRFs of MEGSM1 signals (when the scalar product with the first principal component of sensor orientation was negative) to ensure that all TRFs were estimated in a compatible orientation. This was necessary to warrant the validity of the across-subjects averaging procedure.