Losonczy Attila, Magee Jeffrey C
Neuroscience Center, Louisiana State University Health Science Center, New Orleans, Louisiana 70112, USA.
Neuron. 2006 Apr 20;50(2):291-307. doi: 10.1016/j.neuron.2006.03.016.
Although radial oblique dendrites are a major synaptic input site in CA1 pyramidal neurons, little is known about their integrative properties. We have used multisite two-photon glutamate uncaging to deliver different spatiotemporal input patterns to single branches while simultaneously recording the uncaging-evoked excitatory postsynaptic potentials and local Ca2+ signals. Asynchronous input patterns sum linearly in spite of the spatial clustering and produce Ca2+ signals that are mediated by NMDA receptors (NMDARs). Appropriately timed and sized input patterns ( approximately 20 inputs within approximately 6 ms) produce a supralinear summation due to the initiation of a dendritic spike. The Ca2+ signals associated with synchronous input were larger and mediated by influx through both NMDARs and voltage-gated Ca2+ channels (VGCCs). The oblique spike is a fast Na+ spike whose duration is shaped by the coincident activation of NMDAR, VGCCs, and transient K+ currents. Our results suggest that individual branches can function as single integrative compartments.
尽管放射状斜向树突是CA1锥体神经元的主要突触输入位点，但对其整合特性却知之甚少。我们使用多位点双光子谷氨酸解笼技术，向单个分支传递不同的时空输入模式，同时记录解笼诱发的兴奋性突触后电位和局部Ca2+信号。尽管存在空间聚集，但异步输入模式呈线性相加，并产生由NMDA受体（NMDARs）介导的Ca2+信号。适当定时和大小的输入模式（约6毫秒内约20次输入）由于树突棘的启动而产生超线性相加。与同步输入相关的Ca2+信号更大，由通过NMDARs和电压门控Ca2+通道（VGCCs）的内流介导。斜向棘是一种快速Na+棘，其持续时间由NMDAR、VGCCs和瞬时K+电流的同时激活所塑造。我们的结果表明，单个分支可以作为单个整合隔室发挥作用。
