PERCEPTUAL CONTRIBUTIONS TO OPTIMIZATION OF BREATHING

Besides regulating the energetic cost of breathing, optimization of br eathing may involve the alleviation of an uncomfortable breathing sens ation. In this article, we consider perceptual contributions to the op timization of breathing. Just as the cost function proposed by Poon de pends on ventilation and arterial Pco, so does the sense of dyspnea. C onsequently, we examined the relationship between breathing discomfort and Poon's cost function. Based on our model and psychophysical studi es, it appears that breathing discomfort, which can integrate chemical and mechanical inputs to the respiratory controller, may not operate simply as an estimate of a cost function. We explain how our reflex co ntrol model can dynamically minimize a cost function such as Poon's. A lso, we consider the influence of willful adjustments of ventilation o n breathing discomfort. From this we infer that ventilatory optimizati on may emerge from automatic reflexes and behavioral responses that in volve excitatory chemical and inhibitory neuromechanical feedbacks.