Poleg-Polsky Alon, Diamond Jeffrey S
Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA.
Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA.
Neuron. 2016 Mar 16;89(6):1277-1290. doi: 10.1016/j.neuron.2016.02.013. Epub 2016 Mar 3.
Postsynaptic responses in many CNS neurons are typically small and variable, often making it difficult to distinguish physiologically relevant signals from background noise. To extract salient information, neurons are thought to integrate multiple synaptic inputs and/or selectively amplify specific synaptic activation patterns. Here, we present evidence for a third strategy: directionally selective ganglion cells (DSGCs) in the mouse retina multiplicatively scale visual signals via a mechanism that requires both nonlinear NMDA receptor (NMDAR) conductances in DSGC dendrites and directionally tuned inhibition provided by the upstream retinal circuitry. Postsynaptic multiplication enables DSGCs to discriminate visual motion more accurately in noisy visual conditions without compromising directional tuning. These findings demonstrate a novel role for NMDARs in synaptic processing and provide new insights into how synaptic and network features interact to accomplish physiologically relevant neural computations.
许多中枢神经系统神经元的突触后反应通常较小且多变，这常常使得从背景噪声中区分生理相关信号变得困难。为了提取显著信息，人们认为神经元会整合多个突触输入和/或选择性地放大特定的突触激活模式。在此，我们提供了第三种策略的证据：小鼠视网膜中的方向选择性神经节细胞（DSGCs）通过一种机制对视觉信号进行乘法缩放，该机制既需要DSGC树突中的非线性NMDA受体（NMDAR）电导，也需要上游视网膜回路提供的方向调谐抑制。突触后乘法使DSGCs能够在嘈杂的视觉条件下更准确地辨别视觉运动，而不会影响方向调谐。这些发现证明了NMDARs在突触处理中的新作用，并为突触和网络特征如何相互作用以完成生理相关的神经计算提供了新的见解。
