Bounds of the Ability to Destroy Precise Coincidences by Spike Dithering
Correlation analysis of neuronal spiking activity relies on the availability of distributions for assessing significance. At present, these distributions can only be created by surrogate data. A widely used surrogate, termed dithering, adds a small random offset to all spikes. Due to the biological noise, simultaneous spike emission is registered within a finite coincidence window. Established methods of counting are: (i) partitioning the temporal axis into disjunct bins and (ii) integrating the counts of precise coincidences over multiple relative temporal shifts of the two spike trains. Here, we rigorously analyze for both methods the effectiveness of dithering in destroying precise coincidences. Closed form expressions and bounds are derived for the case where the dither range equals the coincidence window. In this situation disjunct binning detects half of the original coincidences, the multiple shift method recovers three quarters. Thus, only a dither range much larger than the detection window qualifies as a generator of suitable surrogates.
Keywordsmulti-channel recording spike train Monte-Carlo surrogate data correlation
Unable to display preview. Download preview PDF.
- 2.Nowak, L.G., Munk, M.H., Nelson, J.I., James, A., Bullier, J.: Structural basis of cortical synchronization. I. Three types of interhemispheric coupling. J. Neurophysiol. 74(6), 2379–2400 (1995)Google Scholar
- 11.Date, A., Bienenstock, E., Geman, S.: On the temporal resolution of neural activity. Technical report, Divison of Applied Mathematics, Brown University (1998)Google Scholar
- 13.Maldonado, P., Babul, C., Singer, W., Rodriguez, E., Berger, D., Grün, S.: Dissociation between discharge rates and synchrony in primary visual cortex of monkeys viewing natural images (submitted)Google Scholar
- 14.Gerstein, G.L.: Searching for significance in spatio-temporal firing patterns. Acta Neurobiol. Exp (Wars.) 2(64), 203–207 (2004)Google Scholar