Coherence spectra for the period T2. Superimposed frequency-coherence plots for each subject in beta- and gamma-range for the three conditions W1 (dotted line), W2 (thin line) and W3 (thick line) during the period T2. The confidence level at 95% is marked with a horizontal thin line. Significant broad-band CMC are observed in period T2: with CMC in beta-range CMC in three subjects (left column) and in gamma-range in five subjects (right column). Note the presence of a narrow-band CMC peaking at around 2 Hz in all 5 gamma-subjects during 1.6 Hz force modulation.