T-sne embeddings of the same PD128 data set for a series of electrode densities (the electrode configuration is shown at the top of each subplot with blue being the used channels). The color code represents the manually sorting of the spikes done on the full (128 channels) t-sne embedded data set. The way the different color groups start to break up and merge with each other over the consecutive electrode configurations visually depicts the increased difficulty of the spike sorting problem for probes with reduced densities. For the last two densities (subplots E and F) the electrodes are far enough from each other to ensure that each spike is seen by only one electrode. The quality of these embeddings makes immediately obvious the usefulness of the multiple, spatially separated, channels with information about each spike.