Figure 1. Sorting network gamma oscillations: an analogy with neuron spike sorting.

A) Action potentials discharged by nearby neurons are recorded on the same electrode, resulting in an aggregated signal of multi-unit activity (MUA). Spike sorting relies on sampling of the action potentials by an array of recording sites that allow assigning each action potential to an individual neuron (color-coded single-units), notably using spike waveform features. B) Likewise, multiple oscillations generated by different rhythm-generating circuits project repetitive volleys of synchronous action potentials via axonal pathways to their downstream targets, producing synaptic current-generating sources that sum up in the extracellular space and give rise to the recorded local field potentials (broad-band LFPs). These individual (color-coded) oscillations can then be demixed and assigned to their generating sources and subcellular domains, notably using their spectro-temporal and spatial characteristics.