TY - JOUR T1 - Detecting pairwise correlations in spike trains: an objective comparison of methods and application to the study of retinal waves JF - bioRxiv DO - 10.1101/006635 SP - 006635 AU - Catherine S Cutts AU - Stephen J Eglen Y1 - 2014/01/01 UR - http://biorxiv.org/content/early/2014/09/09/006635.abstract N2 - Correlations in neuronal spike times are thought to be key to processing in many neural systems. Many measures have been proposed to summarise these correlations and of these the correlation index is widely used and is the standard in studies of spontaneous retinal activity. We show that this measure has two undesirable properties: it is unbounded above and confounded by firing rate. We list properties needed for a measure to fairly quantify and compare correlations and we propose a novel measure of correlation — the Spike Time Tiling Coefficient. This coefficient, the correlation index and 33 other measures of correlation of spike times are blindly tested for the required properties on synthetic and experimental data. On the basis of this, we propose a measure (the Spike Time Tiling Coefficient) to replace the correlation index. To demonstrate the benefits of this measure, we re-analyse data from seven key studies which previously used the correlation index to investigate the nature of spontaneous activity. We re-analyse data from β2(KO) and β2(TG) mutants, mutants lacking connexin isoforms and also the age-dependent changes in wild type and β2(KO) correlations. Re-analysis of the data using the proposed measure can significantly change the conclusions. It leads to better quantification of correlations and therefore better inference from the data. We hope that the proposed measure will have wide applications, and will help clarify the role of activity in retinotopic map formation.ISIInterspike intervalIQRInterquartile rangeMEAMultielectrode arrayTRecording timeΔtTime window of synchronyaVector of spike times of neuron ANANumber of spikes from neuron A in recordingNA,B[−Δt,Δt]Number of spike pairs where a spike from neuron A occurs within ±Δt of a spike from neuron BλAfiring rate of spike train AλSfiring rate of spikes shared between two trainsdbin widthAvector of binned spike counts of Aωsliding window widthĀGlobal average of AÃLocal average of AAspike train of neuron A represented as a signalFconvolution kernelA′convolution of A with F ER -