Figure 1 Configuration of the testing paradigm. Vertical arrows indicate threshold tracking of test potential (set to 70% of the maximal potential, as measured on stimulus channel (Ch) 1). A supramaximal stimulus, 20% greater than stimulus channel 1, was delivered on stimulus channel 2. Stimulus channel 3 was of fixed intensity to produce a potential 70% of maximum. Unconditioned test stimuli of 0.1 ms and 1 ms duration were delivered on stimulus channels 4 and 5, respectively. On stimulus channel 6, an interstimulus interval of 7 ms was used to measure superexcitability. Stimuli were delivered at 1.2 Hz, rotating through the six stimulus channels sequentially. APB, abductor pollicis brevis.