Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA.
Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA.
Curr Biol. 2022 Sep 12;32(17):3758-3772.e4. doi: 10.1016/j.cub.2022.07.048. Epub 2022 Aug 15.
Sweet and bitter compounds excite different sensory cells and drive opposing behaviors. However, it remains unclear how sweet and bitter tastes are represented by the neural circuits linking sensation to behavior. To investigate this question in Drosophila, we devised trans-Tango(activity), a strategy for calcium imaging of second-order gustatory projection neurons based on trans-Tango, a genetic transsynaptic tracing technique. We found spatial overlap between the projection neuron populations activated by sweet and bitter tastants. The spatial representation of bitter tastants in the projection neurons was consistent, while that of sweet tastants was heterogeneous. Furthermore, we discovered that bitter tastants evoke responses in the gustatory receptor neurons and projection neurons upon both stimulus onset and offset and that bitter offset and sweet onset excite overlapping second-order projections. These findings demonstrate an unexpected complexity in the representation of sweet and bitter tastants by second-order neurons of the gustatory circuit.
甜和苦化合物会刺激不同的感觉细胞，并驱动相反的行为。然而，甜味和苦味如何通过连接感觉和行为的神经回路来表达，目前仍不清楚。为了在果蝇中研究这个问题，我们设计了 trans-Tango(activity)，这是一种基于 trans-Tango 的用于第二级味觉投射神经元钙成像的策略，trans-Tango 是一种遗传的突触追踪技术。我们发现甜味和苦味刺激物激活的投射神经元群体之间存在空间重叠。苦味刺激物在投射神经元中的空间表示是一致的，而甜味刺激物的空间表示则是异质的。此外，我们发现苦味刺激物在刺激开始和结束时都会在味觉受体神经元和投射神经元中引起反应，而苦味结束和甜味开始会激发重叠的第二级投射。这些发现表明，味觉回路的第二级神经元对甜和苦味觉的表示存在意想不到的复杂性。
