Spike–Gamma Phase Relationship in the Visual Cortex

Gamma oscillations (30–70 Hz) have been hypothesized to play a role in cortical function. Most of the proposed mechanisms involve rhythmic modulation of neuronal excitability at gamma frequencies, leading to modulation of spike timing relative to the rhythm. It first shows that the gamma band could be more privileged than other frequencies in observing spike–field interactions even in the absence of natural gamma rhythmicity and discuss several biases in spike–gamma phase estimation. It then discusses the expected spike–gamma phase according to several hypotheses. However, this phase relationship is expected even when gamma is a byproduct of excitatory-inhibitory interactions. Finally, given that gamma occurs in short bursts, it argues that the debate over the role of gamma is a matter of semantics.