Department of Neurobiology, Duke University, Durham, North Carolina, 27710.
Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3.
J Neurosci. 2020 Jul 22;40(30):5807-5819. doi: 10.1523/JNEUROSCI.0564-20.2020. Epub 2020 Jun 19.
Simple stimuli have been critical to understanding neural population codes in sensory systems. Yet it remains necessary to determine the extent to which this understanding generalizes to more complex conditions. To examine this problem, we measured how populations of direction-selective ganglion cells (DSGCs) from the retinas of male and female mice respond to a global motion stimulus with its direction and speed changing dynamically. We then examined the encoding and decoding of motion direction in both individual and populations of DSGCs. Individual cells integrated global motion over ∼200 ms, and responses were tuned to direction. However, responses were sparse and broadly tuned, which severely limited decoding performance from small DSGC populations. In contrast, larger populations compensated for response sparsity, enabling decoding with high temporal precision (<100 ms). At these timescales, correlated spiking was minimal and had little impact on decoding performance, unlike results obtained using simpler local motion stimuli decoded over longer timescales. We use these data to define different DSGC population decoding regimes that use or mitigate correlated spiking to achieve high-spatial versus high-temporal resolution. ON-OFF direction-selective ganglion cells (ooDSGCs) in the mammalian retina are typically thought to signal local motion to the brain. However, several recent studies suggest they may signal global motion. Here we analyze the fidelity of encoding and decoding global motion in a natural scene across large populations of ooDSGCs. We show that large populations of DSGCs are capable of signaling rapid changes in global motion.
简单的刺激对于理解感觉系统中的神经群体代码至关重要。然而，仍有必要确定这种理解在多大程度上适用于更复杂的情况。为了研究这个问题，我们测量了雄性和雌性小鼠视网膜中的方向选择性神经节细胞（DSGCs）群体对方向和速度不断变化的全局运动刺激的反应。然后，我们检查了个体和 DSGCs 群体中运动方向的编码和解码。单个细胞对全局运动进行了约 200 毫秒的积分，并且对方向进行了调谐。然而，反应稀疏且广泛调谐，这严重限制了从小的 DSGC 群体进行解码的性能。相比之下，更大的群体弥补了反应稀疏性，能够以高时间精度（<100 毫秒）进行解码。在这些时间尺度上，相关的尖峰活动很少，对解码性能的影响很小，这与使用更简单的局部运动刺激在更长时间尺度上解码的结果不同。我们使用这些数据来定义不同的 DSGC 群体解码模式，这些模式使用或减轻相关的尖峰活动，以实现高空间分辨率与高时间分辨率。哺乳动物视网膜中的 ON-OFF 方向选择性神经节细胞（ooDSGCs）通常被认为向大脑传递局部运动信息。然而，最近的几项研究表明，它们可能传递全局运动信息。在这里，我们分析了在 ooDSGCs 的大群体中对自然场景中的全局运动进行编码和解码的保真度。我们表明，大量的 DSGC 群体能够传递全球运动的快速变化。
