Fig. 3. Ensemble averages of electromyographic (EMG) activity of the external
intercostal muscle. The pattern of bursting in uncoupled breath averages is
similar in all dogs, and its relationship to ventilation reveals an
inspiratory function for this muscle. The pattern of activity averaged
relative to the stride is more variable, but a clear bursting pattern is
present, indicating a locomotor function. Samples are from four dogs
(A—D), and the average across four dogs (E), with ventilatory (bold
lines) and acceleration (thin lines) traces to reveal relationships to breath
and stride (F). IF indicates ipsilateral forelimb support and CF contralateral
forelimb support in the footfall bars at the bottom. All traces are on the
same time scale. Exp., expiration; Insp., inspiration.
