Single Subject Data.

<p>Each column of this figure refers to the effects of a different substance: placebo (A,D,G,J), propranolol (B,E,H,K) and salbutamol (C,F,I,L). A–C, effect on postural tremor during an index finger extension task. Traces show the power spectrum of the finger acceleration, before and after substance ingestion. Yellow shaded region corresponds to the band of physiological tremor (6.2–11.9 Hz). D–F, effect on EMG power. G–I, effect on EEG power. J–L, effect on corticomuscular coherence. In (D–L), all measurements were made during the second hold phase of a hold-ramp-hold auxotonic precision grip task (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049088#s2" target="_blank">Methods</a>). Yellow shaded region marks the 15.3–32.2 Hz band of beta oscillations. EMG power spectra (D–F) and corticomuscular coherence (J–L) have been averaged over all five muscles recorded. In (J–L), horizontal dashed lines indicate the significance level for the averaged coherence.