Dendritic spikes in thin dendritic branches (basal and oblique dendrites) are traditionally inferred from spikelets measured in the cell body. Here, we used laser-spot voltage-sensitive dye imaging in cortical pyramidal neurons (rat brain slices) to investigate the voltage waveforms of dendritic potentials occurring in response to spatially-restricted glutamatergic inputs. Local dendritic potentials lasted 200-500 ms and propagated to the cell body, where they caused sustained 10-20 mV depolarizations. Plateau potentials propagating from dendrite to soma, and action potentials propagating from soma to dendrite, created complex voltage waveforms in the middle of the thin basal dendrite, comprised of local sodium spikelets, local plateau potentials, and back-propagating action potentials, superimposed on each other. Our model replicated these voltage waveforms across a gradient of glutamatergic stimulation intensities. Model then predicted that somatic input resistance (Rin) and membrane time constant (TAU) may reduce during dendritic plateau potential. We then tested these model predictions in real neurons, and found that model correctly predicted the direction of Rin and TAU change, but not the magnitude. In summary, dendritic plateau potentials occurring in basal and oblique branches put pyramidal neurons into an activated neuronal state ("prepared state"), characterized by depolarized membrane potential, and smaller, but faster membrane responses. The prepared state provides a time window of 200-500 ms during which cortical neurons are particularly excitable and capable of following afferent inputs. At the network level, this predicts that sets of cells with simultaneous plateaus would provide cellular substrate for the formation of functional neuronal ensembles.

中文翻译：

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局部谷氨酸介导的树突平台电位改变皮质锥体神经元的状态

细树突分支（基部和斜树突）中的树突尖峰传统上是从细胞体中测量的小穗中推断出来的。在这里，我们在皮质锥体神经元（大鼠脑切片）中使用激光点电压敏感染料成像来研究响应空间受限的谷氨酸能输入而发生的树突状电位的电压波形。局部树突电位持续 200-500 毫秒并传播到细胞体，在那里它们引起持续的 10-20 mV 去极化。从树突传播到体细胞的平台电位，以及从体细胞传播到树突的动作电位，在薄的基底树突中间产生复杂的电压波形，由局部钠小穗、局部平台电位和反向传播动作电位组成，叠加在每个树突上其他。我们的模型在谷氨酸能刺激强度的梯度上复制了这些电压波形。然后模型预测，在树突平台电位期间，体细胞输入电阻 (Rin) 和膜时间常数 (TAU) 可能会降低。然后我们在真实神经元中测试了这些模型预测，发现该模型正确预测了 Rin 和 TAU 变化的方向，但没有预测幅度。总之，发生在基底和斜支的树突平台电位将锥体神经元置于激活的神经元状态（“准备状态”），其特征是去极化膜电位和更小但更快的膜反应。准备状态提供了一个 200-500 毫秒的时间窗口，在此期间皮质神经元特别容易兴奋并且能够跟随传入输入。在网络层面，