Respiratory-related-evoked potential measures of respiratory sensory gating in attend and ignore conditions.

Respiratory sensory gating is evidenced by decreased respiratory-related-evoked potentials (RREP) amplitude of the N1 peak for the second stimulus (S2) when two occlusions are separated by a 500-millisecond interval. The RREP N1 peak amplitude ratio of the S2 and the first occlusion (S1), S2/S1, is usually <0.5. Controlled attention of respiratory loads is measured by the P300 peak of the RREP. We hypothesized that the paired occlusion elicited N1 and the P300 peak amplitudes will be modulated by controlled attention. The RREP was recorded in ignore and attend trials. The amplitudes of the RREP Nf, P1, N1, and P300 peaks for S1 and S2 and the S2/S1 ratios were measured for both trials. The S1 amplitudes of the Nf, P1, and N1 peaks were not significantly different between the attend and ignore conditions. The S2 Nf, P1, and N1 peak amplitudes were not significantly different between conditions but were all significantly less than S1. The S2/S1 ratios for Nf, P1, and N1 peaks were not significantly different between the attend and ignore conditions. The S1 RREP P300 peak amplitude in attend trials was significantly greater than in ignore trails. The attend S1 P300 amplitude was significantly greater than the attend S2 amplitude. The attend P300 S2/S1 ratio was significantly less than the ignore ratio. These results demonstrated that respiratory gating is evident in both attend and ignore conditions. The P300 peak S2/S1 ratio is consistent with controlled attention modulation of central neural gating of respiratory mechanosensation.