Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59056, Brazil.
J Neurosci. 2013 Jan 23;33(4):1535-9. doi: 10.1523/JNEUROSCI.4217-12.2013.
Recent reports converge to the idea that high-frequency oscillations in local field potentials (LFPs) represent multiunit activity. In particular, the amplitude of LFP activity above 100 Hz-commonly referred to as "high-gamma" or "epsilon" band-was found to correlate with firing rate. However, other studies suggest the existence of true LFP oscillations at this frequency range that are different from the well established ripple oscillations. Using multisite recordings of the hippocampus of freely moving rats, we show here that high-frequency LFP oscillations can represent either the spectral leakage of spiking activity or a genuine rhythm, depending on recording location. Both spike-leaked, spurious activity and true fast oscillations couple to theta phase; however, the two phenomena can be clearly distinguished by other key features, such as preferred coupling phase and spectral signatures. Our results argue against the idea that all high-frequency LFP activity stems from spike contamination and suggest avoiding defining brain rhythms solely based on frequency range.
最近的报告表明，局部场电位（LFPs）中的高频振荡代表多单位活动。特别是，超过 100 Hz 的 LFP 活动幅度——通常称为“高伽马”或“epsilon”频段——与放电率相关。然而，其他研究表明，在这个频率范围内存在真正的 LFP 振荡，与已建立的涟漪振荡不同。使用自由移动大鼠海马的多部位记录，我们在这里表明，高频 LFP 振荡可以代表尖峰活动的频谱泄漏，也可以代表真实的节律，这取决于记录位置。尖峰泄漏的、虚假的活动和真正的快速振荡都与 theta 相位耦合；然而，这两种现象可以通过其他关键特征来清楚地区分，例如首选耦合相位和频谱特征。我们的结果反对所有高频 LFP 活动都源于尖峰污染的观点，并建议避免仅基于频率范围来定义脑节律。
