Synchronization analysis using joint peri-stimulus time histograms for human motor units

Junichi Ushiba, Yutaka Tomita, Yoshihisa Masakado

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The concurrence of action potentials from two motor units (MUs) happens more frequently in human than what one would expect by chance. It can be visualized as the central peak of the Cross-Correlogram of spike trains from two MUs. It is widely believed that a common pre-synaptic input to motoneurons from the cortical tract generates the concurrence. A number of synchronization indices have been proposed in order to evaluate the quantity of the common input, however, these indices are dependent on the firing rates of the MUs. To resolve this issue, we introduce a new synchronization index β using a joint peri-stimulus time histograms (JPSTH). In this paper, we discuss the dependence of synchronization indices on firing rates using a spike model, and the application of JPSTH and the index β to experimental data for the quantitative analysis of MU synchronization. We confirm that the novel index β represents the synchronization state independently from firing rates, and that it also accurately traces event-related temporal modulation of synchronization. In conclusion, we consider the index β to be a valuable index for the analysis of MU synchronization.

Original languageEnglish
Pages (from-to)163-171
Number of pages9
JournalJournal of Neuroscience Methods
Issue number2
Publication statusPublished - 2002 Oct 30


  • Cross-Correlograms
  • Human subjects
  • Joint peri-stimulus time histograms
  • Motor unit
  • Normalization technique
  • Synchronization

ASJC Scopus subject areas

  • Neuroscience(all)


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