Cash S, Yuste R
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Neuron. 1999 Feb;22(2):383-94. doi: 10.1016/s0896-6273(00)81098-3.
A fundamental problem in neurobiology is understanding the arithmetic that dendrites use to integrate inputs. The impact of dendritic morphology and active conductances on input summation is still unknown. To study this, we use glutamate iontophoresis and synaptic stimulation to position pairs of excitatory inputs throughout the apical, oblique, and basal dendrites of CA1 pyramidal neurons in rat hippocampal slices. Under a variety of stimulation regimes, we find a linear summation of most input combinations that is implemented by a surprising balance of boosting and shunting mechanisms. Active conductances in dendrites paradoxically serve to make summation linear. This "active linearity" can reconcile predictions from cable theory with the observed linear summation in vivo and suggests that a simple arithmetic is used by apparently complex dendritic trees.
神经生物学中的一个基本问题是理解树突用于整合输入信号的算法。树突形态和主动电导对输入信号总和的影响仍然未知。为了研究这一问题，我们使用谷氨酸离子透入法和突触刺激，在大鼠海马切片的CA1锥体神经元的顶树突、斜树突和基底树突中定位成对的兴奋性输入信号。在各种刺激模式下，我们发现大多数输入信号组合呈线性总和，这是由增强和分流机制之间惊人的平衡实现的。树突中的主动电导反常地使总和呈线性。这种“主动线性”可以使电缆理论的预测与体内观察到的线性总和相协调，并表明看似复杂的树突树使用了一种简单的算法。
