Spike-field coupling predicts distinct oscillatory waveforms in the primate brain

Neural oscillations provide unique insights into brain function in health and disease. Recently, the non-sinusoidal waveform shape of oscillations has gained interest as a promising biomarker of underlying network physiology. However, the relationship between spiking activity and the oscillatory shape of population signals such as the local field potential (LFP) is unknown. To address this, we simultaneously recorded LFP and multi-unit spiking activity in 8 different cortical and subcortical brain areas of macaque monkeys. We applied Fourier-based waveform analysis to LFP oscillations and systematically investigated the relationship between waveform shape and multiunit activity. We found a ubiquitous coupling of spiking activity to LFP oscillations. These oscillations showed different waveforms in different cortical and subcortical areas. Furthermore, we found that the strength and phase of spike-field coupling predicted the shape of the oscillatory waveform. Our results provide new insights into the relationship between the waveforms of oscillations and the underlying network activity. Establishing this relationship may allow inferences about network activity from non-invasive recordings of brain rhythms in healthy and diseased human brains.