Fig. 6.

Group results of correlation analysis between pairs of breath-holding datasets that determine the effects of impaired consistency (All15/Avg15.0), impaired ability (All10/All20), or both (Avg12.5/Avg17.5). Voxels within GM showed greater z(r) correlation using the End-tidal CO₂ regressors than using the Time-scaled Ramps regressors in all comparisons. The All 20s Ramps model resulted in greater correlation than the Time-scaled Ramps model in the All15/Avg15.0 and All10/All20 comparisons. The End-tidal CO₂ model showed greater correlation that the All 20s Ramps model in only the Avg12.5/Avg17.5 comparison (*p < 0.05, paired t-tests, corrected for multiple comparisons).