Unitary Event Analysis (UE)

Unitary Event (UE) analysis is a statistical method to analyze in a time resolved manner excess spike correlation between simultaneously recorded neurons by comparing the empirical spike coincidences (precision of a few ms) to the expected number based on the firing rates of the neurons (see [ue1]).


It has been proposed that cortical neurons organize dynamically into functional groups (“cell assemblies”) by the temporal structure of their joint spiking activity. The Unitary Events analysis method detects conspicuous patterns of synchronous spike activity among simultaneously recorded single neurons. The statistical significance of a pattern is evaluated by comparing the empirical number of occurrences to the number expected given the firing rates of the neurons. Key elements of the method are the proper formulation of the null hypothesis and the derivation of the corresponding count distribution of synchronous spike events used in the significance test. The analysis is performed in a sliding window manner and yields a time-resolved measure of significant spike synchrony. For further reading, see [ue2][ue3][ue4][ue5][ue6][ue1].


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Functions overview

jointJ_window_analysis(spiketrains[, ...]) Calculates the joint surprise in a sliding window fashion.

Author Contributions

  • Vahid Rostami (VR)
  • Sonja Gruen (SG)
  • Markus Diesmann (MD)

VR implemented the method, SG and MD provided guidance.


[ue1](1, 2) S. Grün, M. Diesmann, F. Grammont, A. Riehle, and A. Aertsen. Detecting unitary events without discretization of time. J. Neurosci. Meth., 94(1):67–79, 1999. doi:10.1016/s0165-0270(99)00126-0.
[ue2]A. Riehle, S. Grün, M. Diesmann, and A. Aertsen. Spike synchronization and rate modulation differentially involved in motor cortical function. Science, 278(5345):1950–1953, 1997. doi:10.1126/science.278.5345.1950.
[ue3]S. Grün, M. Diesmann, and A. Aertsen. Unitary events in multiple single-neuron spiking activity: i. detection and significance. Neural Comp., 14(1):43–80, 2002. doi:10.1162/089976602753284455.
[ue4]S. Grün, M. Diesmann, and A. Aertsen. Unitary events in multiple single-neuron spiking activity: ii. nonstationary data. Neural Comp., 14(1):81–119, 2002. doi:10.1162/089976602753284464.
[ue5]S. Grün, A. Riehle, and M. Diesmann. Effects across trial non-stationarity on joint-spike events. Biol. Cyb., 88(5):335–51, 2003. doi:10.1007/s00422-002-0386-2.
[ue6]S. Grün. Data-driven significance estimation of precise spike correlation. J. Neurophysiol., pages 1126–1140, 2009. doi:10.1152/jn.00093.2008.