Fig 1. Time line of experiments.

In the main experiment, motor-evoked potentials (MEPs) were recorded at all time points (circles; B0, B1-B2, P1-P9) with SI_1mV, i.e. the stimulation intensity that evoked MEPs of, on average, 1mV peak-to-peak amplitude in the resting abductor pollicis brevis muscle at baseline (time point B0). Note that subjects took part in four experimental sessions in a crossover design with different intervals between the consecutive sessions of two identical LTP-like plasticity inducing PAS_LTP protocols (PAS₁, PAS₂): 10min (IPI₁₀), 30min (IPI₃₀), 60min (IPI₆₀), and 180min (IPI₁₈₀). In the control experiment (IPI_30adj) SI_1mV was readjusted at time point B2 to match baseline MEPs of 1mV peak-to-peak amplitude (SI'_1mV). Otherwise, the control experiment was identical to the IPI₃₀ condition of the main experiment.