Multineuron recordings and the analysis of state dependent network configurations in respiratory neuron assemblies

The aim of this research was to search for variations in discharge synchrony among midline neurons during the respiratory cycle. Cats were anesthetized, paralyzed, bilaterally vagotomized, and artificially ventilated. Simultaneously monitored neurons in n. raphe obscurus and n. raphe magnus were analyzed with spike train cross-correlation, snowflakes, and the gravitational representation. Multiple concurrent short time scale correlations were detected. Inferred networks were simulated. The resultant spike output was analyzed and found to be sufficient to generate representations similar to the biological data. Samples from interleaved inspiratory and expiratory phases of the same data set provided evidence for respiratory phase-dependent network configurations. Neurons exhibited significant alterations in impulse synchrony during the respiratory cycle without changes in firing rate, as measured by conventional averaging methods. The results have implications for the study of concurrent processes