Schmidt-Hieber Christoph, Toleikyte Gabija, Aitchison Laurence, Roth Arnd, Clark Beverley A, Branco Tiago, Häusser Michael
Wolfson Institute for Biomedical Research and Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
Institut Pasteur, Paris, France.
Nat Neurosci. 2017 Aug;20(8):1114-1121. doi: 10.1038/nn.4582. Epub 2017 Jun 19.
Understanding how active dendrites are exploited for behaviorally relevant computations is a fundamental challenge in neuroscience. Grid cells in medial entorhinal cortex are an attractive model system for addressing this question, as the computation they perform is clear: they convert synaptic inputs into spatially modulated, periodic firing. Whether active dendrites contribute to the generation of the dual temporal and rate codes characteristic of grid cell output is unknown. We show that dendrites of medial entorhinal cortex neurons are highly excitable and exhibit a supralinear input-output function in vitro, while in vivo recordings reveal membrane potential signatures consistent with recruitment of active dendritic conductances. By incorporating these nonlinear dynamics into grid cell models, we show that they can sharpen the precision of the temporal code and enhance the robustness of the rate code, thereby supporting a stable, accurate representation of space under varying environmental conditions. Our results suggest that active dendrites may therefore constitute a key cellular mechanism for ensuring reliable spatial navigation.
理解活跃的树突如何被用于与行为相关的计算是神经科学中的一项基本挑战。内嗅皮层中的网格细胞是解决这个问题的一个有吸引力的模型系统，因为它们执行的计算很明确：它们将突触输入转化为空间调制的周期性放电。活跃的树突是否有助于产生网格细胞输出特有的双重时间和速率编码尚不清楚。我们发现，内嗅皮层神经元的树突具有高度兴奋性，并且在体外表现出超线性输入-输出功能，而体内记录揭示了与活跃树突电导募集一致的膜电位特征。通过将这些非线性动力学纳入网格细胞模型，我们表明它们可以提高时间编码的精度并增强速率编码的稳健性，从而在不同环境条件下支持对空间的稳定、准确表征。因此，我们的结果表明，活跃的树突可能构成确保可靠空间导航的关键细胞机制。
