To date, surprisingly little is known about the neuronal origins of HFO. Although the high frequency range suggest a reflection of multiunit spiking activity, the fact that a clear and relatively narrow peak can be observed in the power spectrum implies an oscillatory component. In order to resolve this issue, Yang and colleagues (2014) simultaneously recorded single unit activity and local field potentials from a pair of micro- and macroelectrode contacts during DBS surgery of the STN. Notably, both neuronal spiking and HFO were locked to the phase of beta band oscillations but their occurrence was uncorrelated, suggesting that spiking activity does not directly contribute to beta/HFO as such. This has been further corroborated by Wang et al. (2014) who showed that the removal of spikes from the microelectrode time series marginally affected the spectral power of HFO.
