Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA.
Neuroscience. 2018 Apr 15;376:80-93. doi: 10.1016/j.neuroscience.2018.02.014. Epub 2018 Feb 17.
The hippocampus plays a critical role in learning, memory, and spatial processing through coordinated network activity including theta and gamma oscillations. Recent evidence suggests that hippocampal subregions (e.g., CA1) can generate these oscillations at the network level, at least in part, through GABAergic interneurons. However, it is unclear whether specific GABAergic interneurons generate intrinsic theta and/or gamma oscillations at the single-cell level. Since major types of CA1 interneurons (i.e., parvalbumin-positive basket cells (PVBCs), cannabinoid type 1 receptor-positive basket cells (CBBCs), Schaffer collateral-associated cells (SCAs), neurogliaform cells and ivy cells) are thought to play key roles in network theta and gamma oscillations in the hippocampus, we tested the hypothesis that these cells generate intrinsic perithreshold oscillations at the single-cell level. We performed whole-cell patch-clamp recordings from GABAergic interneurons in the CA1 region of the mouse hippocampus in the presence of synaptic blockers to identify intrinsic perithreshold membrane potential oscillations. The majority of PVBCs (83%), but not the other interneuron subtypes, produced intrinsic perithreshold gamma oscillations if the membrane potential remained above -45 mV. In contrast, CBBCs, SCAs, neurogliaform cells, ivy cells, and the remaining PVBCs (17%) produced intrinsic theta, but not gamma, oscillations. These oscillations were prevented by blockers of persistent sodium current. These data demonstrate that the major types of hippocampal interneurons produce distinct frequency bands of intrinsic perithreshold membrane oscillations.
海马体通过协调包括 theta 和 gamma 振荡在内的网络活动，在学习、记忆和空间处理中发挥关键作用。最近的证据表明，海马体的亚区（例如 CA1）至少部分通过 GABA 能中间神经元在网络水平上产生这些振荡。然而，尚不清楚特定的 GABA 能中间神经元是否在单细胞水平上产生内在的 theta 和/或 gamma 振荡。由于 CA1 中间神经元的主要类型（即，parvalbumin 阳性basket 细胞（PVBCs）、大麻素 1 型受体阳性 basket 细胞（CBBCs）、Schaffer 侧支相关细胞（SCAs）、神经胶质形成细胞和常春藤细胞）被认为在海马体的网络 theta 和 gamma 振荡中发挥关键作用，我们检验了这些细胞在单细胞水平上产生内在阈下振荡的假设。我们在存在突触阻滞剂的情况下，对 CA1 区的 GABA 能中间神经元进行全细胞膜片钳记录，以鉴定内在阈下膜电位振荡。大多数 PVBCs（83%），但不是其他中间神经元亚型，如果膜电位保持在-45 mV 以上，则产生内在阈下 gamma 振荡。相比之下，CBBCs、SCAs、神经胶质形成细胞、常春藤细胞和剩余的 PVBCs（17%）产生内在的 theta，但不是 gamma 振荡。这些振荡被持续钠电流阻滞剂所阻止。这些数据表明，海马体中间神经元的主要类型产生不同频率范围的内在阈下膜振荡。
