Ganguly Ishani, Heckman Emily L, Litwin-Kumar Ashok, Clowney E Josephine, Behnia Rudy
The Mortimer B. Zuckerman Mind Brain Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA.
Center for Theoretical Neuroscience, Columbia University, New York, NY 10027, USA.
bioRxiv. 2023 Oct 14:2023.10.12.561793. doi: 10.1101/2023.10.12.561793.
The arthropod mushroom body is well-studied as an expansion layer that represents olfactory stimuli and links them to contingent events. However, 8% of mushroom body Kenyon cells in receive predominantly visual input, and their tuning and function are poorly understood. Here, we use the FlyWire adult whole-brain connectome to identify inputs to visual Kenyon cells. The types of visual neurons we identify are similar across hemispheres and connectomes with certain inputs highly overrepresented. Many visual projection neurons presynaptic to Kenyon cells receive input from large swathes of visual space, while local visual interneurons, providing smaller fractions of input, receive more spatially restricted signals that may be tuned to specific features of the visual scene. Like olfactory Kenyon cells, visual Kenyon cells receive sparse inputs from different combinations of visual channels, including inputs from multiple optic lobe neuropils. The sets of inputs to individual visual Kenyon cells are consistent with random sampling of available inputs. These connectivity patterns suggest that visual coding in the mushroom body, like olfactory coding, is sparse, distributed, and combinatorial. However, the expansion coding properties appear different, with a specific repertoire of visual inputs projecting onto a relatively small number of visual Kenyon cells.
节肢动物的蘑菇体作为一个扩展层得到了充分研究，它代表嗅觉刺激并将其与偶然事件联系起来。然而，果蝇中8%的蘑菇体肯扬细胞主要接收视觉输入，但其调谐和功能却知之甚少。在这里，我们使用FlyWire成体全脑连接组来识别视觉肯扬细胞的输入。我们识别出的视觉神经元类型在不同半球和连接组中相似，某些输入高度富集。许多与肯扬细胞形成突触前连接的视觉投射神经元接收来自大片视觉空间的输入，而提供较少输入部分的局部视觉中间神经元接收空间上更受限的信号，这些信号可能针对视觉场景的特定特征进行了调谐。与嗅觉肯扬细胞一样，视觉肯扬细胞从不同的视觉通道组合接收稀疏输入，包括来自多个视叶神经纤维网的输入。单个视觉肯扬细胞的输入集与可用输入的随机采样一致。这些连接模式表明，蘑菇体中的视觉编码与嗅觉编码一样，是稀疏的、分布式的和组合式的。然而，扩展编码特性似乎有所不同，特定的视觉输入库投射到相对较少的视觉肯扬细胞上。
