Spatial oversampling and redundancy

A regime in which electrode sites are spaced closer than the spatial reach of an extracellular spike (on the order of tens of micrometres), so that each neuron appears on several neighbouring sites at once. Rather than adding new neurons, the extra sites add multiple views of the same neurons.

This redundancy is deliberately useful: seeing a spike on several sites gives the spatial waveform footprint that modern spike sorting uses to separate overlapping units, and it lets a decoder track a neuron as its apparent position drifts across sites over days. The cost is that raw data volume grows with site count while the number of independent neurons — and therefore the information — grows much more slowly.