IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria.
Nat Neurosci. 2012 Mar 4;15(4):600-6. doi: 10.1038/nn.3060.
CA3 pyramidal neurons are important for memory formation and pattern completion in the hippocampal network. It is generally thought that proximal synapses from the mossy fibers activate these neurons most efficiently, whereas distal inputs from the perforant path have a weaker modulatory influence. We used confocally targeted patch-clamp recording from dendrites and axons to map the activation of rat CA3 pyramidal neurons at the subcellular level. Our results reveal two distinct dendritic domains. In the proximal domain, action potentials initiated in the axon backpropagate actively with large amplitude and fast time course. In the distal domain, Na(+) channel-mediated dendritic spikes are efficiently initiated by waveforms mimicking synaptic events. CA3 pyramidal neuron dendrites showed a high Na(+)-to-K(+) conductance density ratio, providing ideal conditions for active backpropagation and dendritic spike initiation. Dendritic spikes may enhance the computational power of CA3 pyramidal neurons in the hippocampal network.
CA3 锥体神经元对于海马网络中的记忆形成和模式完成很重要。人们普遍认为，来自苔藓纤维的近端突触最有效地激活这些神经元，而来自穿通路径的远端输入具有较弱的调节影响。我们使用共聚焦靶向膜片钳记录从树突和轴突，以在亚细胞水平上绘制大鼠 CA3 锥体神经元的激活图。我们的结果揭示了两个不同的树突域。在近端域中，在轴突中引发的动作电位以大振幅和快速时间进程主动逆行传播。在远端域中，模拟突触事件的波形有效地引发了 Na(+)通道介导的树突棘。CA3 锥体神经元的树突显示出高的 Na(+)到 K(+)电导密度比，为主动逆行传播和树突棘引发提供了理想的条件。树突棘可能会增强海马网络中 CA3 锥体神经元的计算能力。
