Respiratory‐related evoked potentials in chronic obstructive pulmonary disease and healthy aging

Figures

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  FIGURE 1. Flow chart of participants recruitment. Participants had moderate to severe chronic obstruction pulmonary disease (COPD), were age‐matched controls (AMC) or young controls (YC). Some enrolled participants were excluded from analysis as they did not meet inclusion criteria or had incomplete data. Abbreviations: FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; % predicted: percent predicted for age, sex, and ethnicity; and EEG: electroencephalography.

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  FIGURE 2. Respiratory‐related evoked potential (RREP) waveforms from one individual on all scalp locations. Average waveforms of the RREP for all (black), odd (red) and even (blue) trials of EEG in a young control participant. EEG was recorded from 12 frontal, central, central parietal, and parietal locations (FP1 was also recorded in some participants), as well as A1 and A2 on the earlobes and below the right eye to detect eye blinks (EOG). Mouth pressure (MouthP) and ECG were recorded as auxiliary channels and EEG trials were time‐locked to the onset of negative inspiratory pressure evoked by brief airway occlusions. All channels were referenced to linked ears, i.e. A1 and A2, and the amplitude and latencies of the RREP peaks were measured from the Cz, C'z and Pz channels (shaded panels, see Methods). C'z channel was computed as the average of CP1 and CP2 as the C'z location was not available on the EEG cap. See Table 3 for RREP group averages.

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  FIGURE 3. Average respiratory‐related evoked potentials (RREP) and topographic maps for P1, N1, P2, and P3 peaks. Grand average waveforms across all participants of RREPs at (i) C'z, (ii) Cz, and (iii) Pz in chronic obstructive pulmonary disease (COPD; red line), age‐matched controls (AMC; blue line) and young controls (YC; black line). Topographic maps show 2‐dimensional view of EEG across all channels for 20 ms around each peak in the grand average for each group. The peaks are indicated on the EEG channels from which they were measured. †Significant difference in P1 and P2 latency between YC and COPD groups. *Significant difference in N1 amplitude between YC and both COPD and AMC groups. ‡Significant difference in P3 latency between groups (see Table 3).