美国哈佛医学院Rachel I. Wilson小组近期研究表明，感觉运动体验将视觉输入重新映射到航向网络。相关论文于2019年11月20日在线发表在《自然》上。

研究人员使用体内全细胞记录，发现视觉提示可以在指南针神经元中引起突触抑制，而R神经元介导这种抑制。每个指南针神经元仅受特定的视觉提示位置抑制，这表明从R神经元到指南针神经元的许多潜在连接实际上是微弱或沉默的。研究人员还发现，随着飞行探索改变的虚拟现实环境，视觉诱发的抑制模式可以在几分钟内重组。使用钙成像，研究人员证明了这种重组会导致指南针坐标系发生持续变化。因此，这些数据提出了一个模型，其中相关的突触前和突触后活动触发了指南针神经元视觉诱发抑制的相关长期突触抑制。这些发现为相关理论提供了证据，即当与吸引因素动态相结合时，感觉输入的可塑性可以协调自我运动信息和变化的外部线索，从而产生一致的方向感。

据了解，在果蝇大脑中，指南针神经元在导航期间跟踪身体和头部（苍蝇的头部）的方向。在没有视觉提示的情况下，指南针神经元网络会通过整合随时间变化的自我运动信号来估计航向。当存在视觉提示时，网络的估计更加准确。指南针神经元的视觉输入被认为源自称为R神经元（也称为环神经元）的抑制性神经元；R神经元的感受野平铺于视觉空间。每个R神经元的轴突与每个指南针神经元的树突重叠，从而提出了视觉提示如何整合到指南针神经元中的问题。

附：英文原文

Title: Sensorimotor experience remaps visual input to a heading-direction network

Author: Yvette E. Fisher, Jenny Lu, Isabel DAlessandro, Rachel I. Wilson

Issue&Volume: 2019-11-20

Abstract: In the Drosophila brain, compass neurons track the orientation of the body and head (the flys heading) during navigation 1,2. In the absence of visual cues, the compass neuron network estimates heading by integrating self-movement signals over time3,4. When a visual cue is present, the estimate of the network is more accurate1,3. Visual inputs to compass neurons are thought to originate from inhibitory neurons called R neurons (also known as ring neurons); the receptive fields of R neurons tile visual space5. The axon of each R neuron overlaps with the dendrites of every compass neuron6, raising the question of how visual cues are integrated into the compass. Here, using in vivo whole-cell recordings, we show that a visual cue can evoke synaptic inhibition in compass neurons and that R neurons mediate this inhibition. Each compass neuron is inhibited only by specific visual cue positions, indicating that many potential connections from R neurons onto compass neurons are actually weak or silent. We also show that the pattern of visually evoked inhibition can reorganize over minutes as the fly explores an altered virtual-reality environment. Using ensemble calcium imaging, we demonstrate that this reorganization causes persistent changes in the compass coordinate frame. Taken together, our data suggest a model in which correlated pre- and postsynaptic activity triggers associative long-term synaptic depression of visually evoked inhibition in compass neurons. Our findings provide evidence for the theoretical proposal that associative plasticity of sensory inputs, when combined with attractor dynamics, can reconcile self-movement information with changing external cues to generate a coherent sense of direction712. Visual inputs to compass neurons can reorganize over minutes as a fly explores an altered virtual-reality environment.

DOI: 10.1038/s41586-019-1772-4

Source:https://www.nature.com/articles/s41586-019-1772-4