Zhao Meilan, Choi Yun-Sik, Obrietan Karl, Dudek Serena M
National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
J Neurosci. 2007 Oct 31;27(44):12025-32. doi: 10.1523/JNEUROSCI.4094-07.2007.
The hippocampus is critical for some forms of memory and spatial navigation, but previous research has mostly neglected the CA2, a unique region situated between CA3 and CA1. Here, we show that CA2 pyramidal neurons have distinctive physiological characteristics that include an unprecedented synaptic stability. Although basal synaptic currents in CA1 and CA2 are quite similar, synaptic plasticity including long-term potentiation and long-term depression is absent or less likely to be induced with conventional methods of stimulation in CA2. We also find that CA2 neurons have larger leak currents and more negative resting membrane potentials than CA1 neurons, and consequently, more current is required for action potential generation in CA2 neurons. These data suggest that the molecular "conspiracy against plasticity" in CA2 makes it functionally distinct from the other hippocampal CA regions. This work provides critical insight into hippocampal function and may lead to an understanding of the resistance of CA2 to damage from disease, trauma, and hypoxia.
海马体对于某些形式的记忆和空间导航至关重要，但以往的研究大多忽略了CA2，这是一个位于CA3和CA1之间的独特区域。在这里，我们表明CA2锥体神经元具有独特的生理特征，包括前所未有的突触稳定性。尽管CA1和CA2中的基础突触电流非常相似，但传统刺激方法在CA2中不会诱导包括长时程增强和长时程抑制在内的突触可塑性，或者诱导的可能性较小。我们还发现，CA2神经元比CA1神经元具有更大的泄漏电流和更负的静息膜电位，因此，CA2神经元产生动作电位需要更多的电流。这些数据表明，CA2中分子层面“对可塑性的协同抑制”使其在功能上与海马体的其他CA区域不同。这项工作为海马体功能提供了关键见解，并可能有助于理解CA2对疾病、创伤和缺氧损伤的抗性。
