Morphological differences of sigmoidal baroreflex in highly-reactive and non-reactive individuals

The purpose of this paper is to analyze morphological differences in sigmoidal characteristics of baroreflex among two groups of children: highly-reactive and non-reactive. These two groups are separated based on their different autonomic nervous system responses to stressful situations. Baroreflex or baroreceptor reflex is a prompt biological reflex which is stimulated by baroreceptors, and regulated by autonomic nervous system. We applied sigmoid function as the model of baroreflex characteristic while this method is well-accepted by physiologists and engineers in the field. Sigmoid function is defined by using three variables; dynamic range, saturation rate, and inflection point. Any deficiency in this biological reflex, i.e. unwanted variation in the amount of the mentioned variables, results in the baroreflex malfunctioning. In this paper, it is shown that inflection point of the baroreflex characteristic is greater in highly-reactive children compared to non-reactive children. We introduced an optimization problem to estimate unknown parameters of sigmoid function. We also applied a search method named genetic algorithm to solve the optimization problem.