Fig. 3. Ensemble averaging (data from all the subjects) of the inspiratory premotor activities recorded, under the “comfort 1,”“discomfort,” and “comfort 2” and “unsupported breathing” conditions. The double-sided arrow depicts the premotor potential latency. Cz-A+= vertex electroencephalogram derivation; Press = airway opening pressure; Scal EMG = root mean square scalene muscle electromyogram.