Tort Adriano B L, Rotstein Horacio G, Dugladze Tamar, Gloveli Tengis, Kopell Nancy J
Department of Mathematics and Center for Biodynamics, Boston University, Boston, MA 02215, USA.
Proc Natl Acad Sci U S A. 2007 Aug 14;104(33):13490-5. doi: 10.1073/pnas.0705708104. Epub 2007 Aug 6.
Gamma frequency (30-80 Hz) network oscillations have been observed in the hippocampus during several behavioral paradigms in which they are often modulated by a theta frequency (4-12 Hz) oscillation. Interneurons of the hippocampus have been shown to be crucially involved in rhythms generation, and several subtypes with distinct anatomy and physiology have been described. In particular, the oriens lacunosum-moleculare (O-LM) interneurons were shown to synapse on distal apical dendrites of pyramidal cells and to spike preferentially at theta frequency, even in the presence of gamma-field oscillations. O-LM cells have also recently been shown to present higher axonal ramification in the longitudinal axis of the hippocampus. By using a hippocampal network model composed of pyramidal cells and two types of interneurons (O-LM and basket cells), we show here that the O-LM interneurons lead to gamma coherence between anatomically distinct cell modules. We thus propose that this could be a mechanism for coupling longitudinally distant cells excited by entorhinal cortex inputs into gamma-coherent assemblies.
在几种行为范式中，已在海马体中观察到伽马频率（30 - 80赫兹）的网络振荡，在这些范式中，它们常常受到theta频率（4 - 12赫兹）振荡的调制。海马体的中间神经元已被证明在节律产生中起着关键作用，并且已经描述了几种具有不同解剖结构和生理学特性的亚型。特别是，腔隙-分子层（O-LM）中间神经元已被证明与锥体细胞的远端顶树突形成突触，并且即使在存在伽马场振荡的情况下，也优先以theta频率放电。最近还发现O-LM细胞在海马体的纵轴上具有更高的轴突分支。通过使用由锥体细胞和两种类型的中间神经元（O-LM和篮状细胞）组成的海马体网络模型，我们在此表明，O-LM中间神经元导致解剖学上不同的细胞模块之间的伽马相干性。因此，我们提出这可能是一种将由内嗅皮层输入激发的纵向远距离细胞耦合到伽马相干集合体中的机制。
