在单一味觉模式中选择性地整合不同的味觉输入

A fundamental question in sensory processing is how different channels of sensory input are processed to regulate behavior. Different input channels may converge onto common downstream pathways to drive the same behaviors, or they may activate separate pathways to regulate distinct behaviors. We investigated this question in the Drosophila bitter taste system, which contains diverse bitter-sensing cells residing in different taste organs. First, we optogenetically activated subsets of bitter neurons within each organ. These subsets elicited broad and highly overlapping behavioral effects, suggesting that they converge onto common downstream pathways, but we also observed behavioral differences that argue for biased convergence. Consistent with these results, transsynaptic tracing revealed that bitter neurons in different organs connect to overlapping downstream pathways with biased connectivity. We investigated taste processing in one type of downstream bitter neuron that projects to the higher brain. These neurons integrate input from multiple organs and regulate specific taste-related behaviors. We then traced downstream circuits, providing the first glimpse into taste processing in the higher brain. Together, these results reveal that different bitter inputs are selectively integrated early in the circuit, enabling the pooling of information, while the circuit then diverges into multiple pathways that may have different roles.

感官处理中的一个基本问题是如何处理不同的感官输入通道来调节行为。不同的输入通道可以汇聚到共同的下游路径上以驱动相同的行为，或者它们可以激活单独的路径来调节不同的行为。我们在果蝇苦味系统中研究了这个问题，该系统包含不同的苦味感知细胞，它们位于不同的味觉器官中。首先，我们光遗传学激活了每个器官内苦味神经元的亚群。这些亚群引发了广泛且高度重叠的行为效应，表明它们汇聚到共同的下游路径上，但我们也观察到了行为差异，这表明存在偏见的汇聚。与这些结果一致，跨突触追踪显示，不同器官中的苦味神经元连接到具有偏差连接的重叠下游通路。我们研究了一种投射到高级大脑的下游苦味神经元的味觉加工。这些神经元整合来自多个器官的输入，并调节特定的味觉相关行为。然后，我们追踪了下游的回路，为高级大脑的味觉加工提供了第一个线索。总之，这些结果表明，不同的苦味输入在电路的早期被选择性地整合，从而实现了信息的汇集，而电路随后分化为可能具有不同作用的多条路径。

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optoPAD assay

The optoPAD was purchased from Pavel Itskov at Easy Behavior (https://flypad.rocks/), who also provided code to run the assay using Bonsai and to process the data using MATLAB. The design of the optoPAD is described in Moreira et al., 2019, and data processing methods are described in Itskov et al., 2014. Experiments were performed as described in Moreira et al., 2019. Optogenetic activation and silencing were performed using 2.2 or 3.5 V stimulation, respectively. Light onset was triggered immediately upon detection of an interaction with the specified food source, and the light remained on for 1.5 s. Tastants were mixed into 1% agarose.

optoPAD购自Pavel Itskov  Easy Behavior(https://flypad.rocks/)，他还提供了使用Bonsai运行分析和使用MATLAB处理数据的代码。Moreira等人，2019年描述了optoPAD的设计，Itskov等人，2014年描述了数据处理方法。实验如Moreira等人，2019所述进行。分别使用2.2或3.5V刺激进行光遗传学激活和沉默。在检测到与特定食物源的相互作用后，立即触发光启动，并且光保持1.5秒。将品尝剂混合到1%琼脂糖中。