Centre for Neuroscience, Indian Institute of Science, Bangalore, India 560012; email:
Annu Rev Vis Sci. 2022 Sep 15;8:361-381. doi: 10.1146/annurev-vision-100419-104530. Epub 2022 Jun 6.
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. I first show that the gamma band could be more privileged than other frequencies in observing spike-field interactions even in the absence of genuine gamma rhythmicity and discuss several biases in spike-gamma phase estimation. I then discuss the expected spike-gamma phase according to several hypotheses. Inconsistent with the phase-coding hypothesis (but not with others), the spike-gamma phase does not change with changes in stimulus intensity or attentional state, with spikes preferentially occurring 2-4 ms before the trough, but with substantial variability. However, this phase relationship is expected even when gamma is a byproduct of excitatory-inhibitory interactions. Given that gamma occurs in short bursts, I argue that the debate over the role of gamma is a matter of semantics.
伽马振荡（30-70 Hz）被假设在皮质功能中发挥作用。大多数提出的机制都涉及神经元兴奋性在伽马频率下的节律调制，从而导致相对于节律的尖峰时间调制。我首先表明，即使在没有真正的伽马节律性的情况下，伽马频带也可能比其他频率更有优势，观察到尖峰-场相互作用，并讨论了尖峰-伽马相位估计中的几种偏差。然后，我根据几种假设讨论了预期的尖峰-伽马相位。与相位编码假说不一致（但与其他假说一致），尖峰-伽马相位不会随刺激强度或注意状态的变化而变化，尖峰优先出现在波谷前 2-4 ms，但具有很大的可变性。然而，即使伽马是兴奋性-抑制性相互作用的副产品，这种相位关系也是预期的。鉴于伽马发生在短爆发中，我认为关于伽马作用的争论是语义问题。
