Sunday, January 13, 2013

[Comp-neuro] Vastly improved spike train distance (incl. Matlab source codes & movies)

Dear all,
 
may I kindly draw your attention to our paper on the new SPIKE-distance. This improved method opens up several novel possibilities in spike train analysis. Among others, it allows to estimate spike train synchrony online and in real-time.
 
 
Monitoring spike train synchrony
 
Kreuz T, Chicharro D, Houghton C, Andrzejak RG, Mormann F

Abstract: Recently, the SPIKE-distance has been proposed as a parameter-free and time-scale independent measure of spike train synchrony. This measure is time-resolved since it relies on instantaneous estimates of spike train dissimilarity. However, its original definition led to spuriously high instantaneous values for event-like firing patterns. Here we present a substantial improvement of this measure which eliminates this shortcoming. The reliability gained allows us to track changes in instantaneous clustering, i.e., time-localized patterns of (dis)similarity among multiple spike trains. Additional new features include selective and triggered temporal averaging as well as the instantaneous comparison of spike train groups. In a second step, a causal SPIKE-distance is defined such that the instantaneous values of dissimilarity rely on past information only so that time-resolved spike train synchrony can be estimated in real-time. We demonstrate that these methods are capable of extracting valuable information from field data by monitoring the synchrony between neuronal spike trains during an epileptic seizure. Finally, the applicability of both the regular and the real-time SPIKE-distance to continuous data is illustrated on model electroencephalographic (EEG) recordings.

 
The paper is soon to appear in the Journal of Neurophysiology:
 
 
A preprint has also been uploaded on the arXiv (with permission):
 
 
On my webpage you can find the Matlab source codes (including documentation):
 
 
These source codes include a file "Distances_Main_Demo" which reproduces the figures 1-9 and a supplementary movie (see below) from the paper. To provide a better illustration of what is done, the parameter settings for each figure are detailed on the webpage.
[Note that we are in the process of programming a graphical user interface which should be finished in a week or two.]
 
On the same webpage there are also two movies (in both avi and wmv format) which demonstrate the new method best. The first one is described in Fig. 9 of the paper, the second one extends the analysis performed in Fig. 7D-F.
 
Any feedback (on both the paper and the source codes) is very welcome!
 
 
Finally, a shorter review on the SPIKE-distance can be found on Scholarpedia:
 
Kreuz T
SPIKE-distance.
Scholarpedia 7(12), 30652 (2012).
 
With this article I am taking part in the competition for the
 
 
which basically gives prizes to the three articles that have received the most Google +1 votes by January 31. So if this is of interest to you and you have a Google account could you please vote for me. In the top right corner of the article ("SPIKE-distance") you will see the Google +1 button.
 
Thank you very much for your support!
 
 
Best regards,
Thomas Kreuz

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