Spike sorting using Superlets: Identifying feature importance through perturbation

Spike sorting is a technique in the field of neuroscience applied to identify and classify the action potentials (spikes) of neurons in extracellular recordings. This method is important considering that the simultaneous activity of several neurons can be recorded through the use of electrodes, but the recorded signals are often mixed. Extracting the characteristics of individual spikes provides valuable information about the identity of neurons that generate them, the type of cells involved (inhibitory/excitatory), encoding of information in spike rates or spike times, and so on. Therefore, unmixing the spikes recorded on an electrode via spike sorting is crucial. Here, we apply a novel method to extract features of mixed spikes, namely the Superlet transform, which enables the computation of spectral characteristics with a higher resolution. We use machine learning to determine which features of the Superlet spectrum contain the most information about the shapes of individual spikes, thereby enabling their unmixing during spike sorting.