Fig. 3.

Continuous time courses of relative HbO₂ and HbR changes before and after artifact rejection while outdoor bicycling (left), stationary bicycling (middle), and sitting still (right) for three representative subjects. Each trial is baseline corrected to (−10 – 0) s before each hand gripping onset (yellow bars: 20-s hand gripping activation periods). Trials and channels exceeding our noise limits were removed from the data time series and excluded from further analysis. For a valid statistical comparison across the three conditions, we considered only those channels which met the defined quality criteria in all three conditions within a subject. As a result, data denoted by (*) were also excluded from the further analysis. Oscillations of physiological origin are generally more pronounced in the ΔHbO₂ data compared to the ΔHbR Signals. Nevertheless, the prototypical neuro-activation response is seen in many instances, even without event-related averaging.