T-sne embedding of the results of the kilosort algorithm (distances to templates) for the PD128 data set. Colors indicate the different categories that the spikes fall into after using our custom GUI to manually evaluate and correct as necessary kilosort's spike assignments to templates. The SU labeled groupings represent a single unit each. The MU labeled groupings represent a single template each but multiple units. The Noise labeled groupings represent noise that has been picked up by kilosort as spike templates. The SUs after merges and splits have a more complex representation where each single unit can be either one or more groupings and have originally belonged to one or more templates. The Unlabeled groupings represent spikes that could not be assigned to either a single unit, or a multi unit or a noise group. The insert at the top of the figure depicts a zoom-in (x30 magnification) to a point grouping (SU) showing that these groupings are actually comprised of large number of spikes all embedded very close to one another. That compactness indicates a very large similarity in the template distance feature space and a large dissimilarity to any other spike, so it is not surprising that they are the groupings that kilosort has assigned to templates that represent single, easy to define units.