Why must spikes be sampled tens of thousands of times a second while EEG makes do with hundreds? · Grey Matter

A spike lasts about a millisecond and its sharp edges carry frequencies of several kilohertz, and a signal has to be sampled at more than twice its highest frequency to be captured, in practice several times more to keep its shape.

Why must spikes be sampled tens of thousands of times a second while EEG makes do with hundreds?

A spike lasts about a millisecond and its sharp edges carry frequencies of several kilohertz, and a signal has to be sampled at more than twice its highest frequency to be captured, in practice several times more to keep its shape. Neuropixels therefore samples its spike band at 30 kHz, and spike sorting depends on those shapes to tell neighbouring neurons apart. EEG records summed synaptic currents that change slowly and are filtered further by the skull, with little useful power above a few hundred hertz, so hundreds of samples a second to a few thousand are enough.