Comparison of spikes estimated using clustering and binary pursuit.

<p>Each row shows results for one example neuron. Each plot depicts the 2D linear feature space used for clustering (see Fig. 1 ). <b>Left column:</b> Black and gray points indicate spikes obtained by clustering for two cells. Additional spikes obtained for the black cell by binary pursuit (but ignored as outliers by clustering), are scattered in various directions relative to this ellipse (red points). Note that some points do not appear to be outliers within the two dimensions shown, but are outliers in other dimensions. <b>Middle column:</b> When the spikes of these two cells overlap in time, the resulting superimposed waveform is predicted to lie along a trajectory (see Fig. 1 ). Filled black and gray ellipses correspond to the location of isolated spikes for the primary and secondary cells, respectively. Size and shape of ellipses corresponds to the level curve (at one standard deviation) of the estimated (Gaussian) noise distribution. Colored ellipses indicate predicted locations of noisy superimposed waveforms, with color indicating their temporal offset. <b>Right column:</b> Subset of spikes identified by binary pursuit that were either isolated (black and gray points), or overlapping (colored points, with color indicating the temporal offset of the two spikes).