The effect of different emotional imagery scripts on end-tidal CO2 in healthy individuals in a standing position

Abstract

hippocampal mI levels overall. Better asthma control was associated with higher left hippocampal GABA, glutamate, glutamine, and choline levels. In addition, more awakenings due to asthma or greater difficulty sleeping through the night were related to lower levels of these metabolites overall and higher glutamine levels specifically. Discussion: Although specific deficits in metabolite levels were not observed, findings suggest that asthma control and aspects of sleep are associated with variations in metabolite levels in older individuals with asthma. Background: The neural processing of respiratory sensations during physical activity is not well understood. Therefore, we investigated respiratory-related evoked potentials (RREPs) in a new paradigm evoking exercise-induced dyspnea. Methods: Ten healthy participants exercised on a cycle ergometer two times at 10%, 40%, and 70% of their individual maximal work rate (each block 5 minutes). Paired inspiratory occlusions evoked the RREPs in the electroencephalogram. Neural gating of respiratory sensations (NGRS) was calculated as the average N1 peak amplitude of the second (S2) over the first (S1) occlusion of the pair. After each block, participants rated the intensity and unpleasantness of dyspnea and the occlusions. Results: Repeated measures ANOVAs showed a significant increase for both the S1 N1 (F=5.52, p<.05) and S2 N1 (F=7.31, p<.01) peak amplitudes with increasing work rate. Significant a priori polynomial contrasts for both S1 N1 (F=8.10, p<.05) and S2 N1 (F=17.33, p<.01) amplitudes indicated a linear increase. Both S1 N1 and S2 N1 amplitudes showed significant positive correlations with increasing ratings of intensity and unpleasantness of dyspnea and the occlusions (all r's>.43; all p's<.05). The S2/S1 NGRS ratio did not significantly increase with increasing work rate (F=0.92, p=.42) and was not significantly correlated with any of the ratings. Discussion: Increasing exercise-induced dyspnea was paralleled by an increase in both the S1 N1 and S2 N1 peak amplitudes of the RREP. While no significant increase in the S2/S1 ratio was found, the results suggest increased neural processing of respiratory sensations that was linked to increased perception of dyspnea.