Automatic approach for classifying sympathetic quasiperiodic, n:m periodic and aperiodic dynamics produced by lung inflation in rats

A method for classifying non linear interactions between two event series, a forcing input and a forced output, is proposed. The approach allows to classify: 1) independent dynamics; 2) quasiperiodic dynamics; 3) n:m periodic synchronized dynamics in which n events of the forced signal occur every m cycles of the driving signal; 4) aperiodic dynamic. The method is automatic and fully independent of the researcher's judgment. In addition, it calculates the ratio and the strength of the coupling in the case of synchronized dynamics. The method is applied to verify whether sympathetic oscillators underlying the discharges of single postganglionic sympathetic neurons innervating the ventral caudal artery of the rat tail could be synchronized by the lung inflation cycle. The application confirms the capability of the method in classifying the dynamics and the synchronizing action of the lung inflation cycle over the single sympathetic neuron discharges.