Sympathetic activity and the underlying action potentials in sympathetic nerves: A simulation

Xiaorui Tang, Ankit R. Chander, Lawrence P. Schramm

Research output: Contribution to journalArticlepeer-review


Understanding the relationship between activity recorded in sympathetic nerves and the action potentials of the axons that contribute to that activity is important for understanding the processing of sympathetic activity by the central nervous system. Because this relationship cannot be determined experimentally and is difficult to predict analytically, we simulated the summed action potentials of 300 axons. This simulation closely resembled actual sympathetic activity and permitted us to know how many action potentials contributed to each burst of simulated sympathetic activity and the durations and amplitudes of each burst. We used these simulated data to examine a statistical method (cluster analysis) that has been used to identify and quantify bursts of sympathetic activity. Simulation indicated that the integrals of bursts, whether determined directly from the simulation or by integrating bursts detected by cluster analysis, were linearly correlated to the number of action potentials contributing to bursts. The variances of samples of the simulated signal were also linearly correlated to the number of action potentials. The amplitudes of bursts of sympathetic activity were less well correlated to the number of underlying action potentials. A linear relationship existed between the average number of action potentials contributing to simulated bursts and the integral of the amplitude spectra obtained by Fourier transform of the simulated activity. Finally, simulated experiments indicated that relatively brief recordings might be sufficient to detect statistically significant changes in sympathetic activity.

Original languageEnglish (US)
Pages (from-to)R1504-R1513
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number6 54-6
StatePublished - Dec 2003


  • Cluster analysis
  • Multiunit nerve recordings
  • Summating action potentials

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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