Wolfson Institute for Biomedical Research, University College London, London, UK.
Neuron. 2011 Mar 10;69(5):885-92. doi: 10.1016/j.neuron.2011.02.006.
Cortical pyramidal neurons receive thousands of synaptic inputs arriving at different dendritic locations with varying degrees of temporal synchrony. It is not known if different locations along single cortical dendrites integrate excitatory inputs in different ways. Here we have used two-photon glutamate uncaging and compartmental modeling to reveal a gradient of nonlinear synaptic integration in basal and apical oblique dendrites of cortical pyramidal neurons. Excitatory inputs to the proximal dendrite sum linearly and require precise temporal coincidence for effective summation, whereas distal inputs are amplified with high gain and integrated over broader time windows. This allows distal inputs to overcome their electrotonic disadvantage, and become surprisingly more effective than proximal inputs at influencing action potential output. Thus, single dendritic branches can already exhibit nonuniform synaptic integration, with the computational strategy shifting from temporal coding to rate coding along the dendrite.
皮质锥体神经元接收来自不同树突位置的数千个突触输入，其到达的时间具有不同程度的同步性。目前尚不清楚单个皮质树突上的不同位置是否以不同的方式整合兴奋性输入。在这里，我们使用双光子谷氨酸光解和分区建模来揭示皮质锥体神经元的基底和顶端斜形树突中非线性突触整合的梯度。树突近端的兴奋性输入线性叠加，需要精确的时间巧合才能有效叠加，而远端输入则以高增益放大并在更宽的时间窗口内整合。这使得远端输入能够克服其电紧张劣势，并且在影响动作电位输出方面比近端输入更为有效。因此，单个树突分支已经可以表现出非均匀的突触整合，其计算策略从沿着树突的时间编码转变为速率编码。
