Modulation of the blink reflex and P3 component of the startle response during an interoceptive challenge

The blink reflex component of the startle response is potentiated during processing of exteroceptive unpleasant stimuli. In contrast, blink magnitudes are often inhibited during interoceptive challenges. We measured respiration, blink magnitudes, and the P3 component to the acoustic startle probes in 34 participants while breathing against a mild resistance (mask-with-tubing) compared to breathing with no mask. Breathing through a mask with tubing resulted in increased inspiratory resistance as indicated by increased flow rate and tidal volume, a compensatory breathing pattern. Blink magnitudes to probes presented during the mask-with-tubing condition were inhibited compared to no-mask. Likewise, the probe P3 component was smaller during breathing through a mild resistance. These data suggest that startle inhibition during interoceptive challenges might be due to a shift in attention towards the mildly unpleasant interoceptive stimuli.