Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom.
Learn Mem. 2021 Jan 15;28(2):53-71. doi: 10.1101/lm.052159.120. Print 2021 Feb.
Discrimination of sensory signals is essential for an organism to form and retrieve memories of relevance in a given behavioral context. Sensory representations are modified dynamically by changes in behavioral state, facilitating context-dependent selection of behavior, through signals carried by noradrenergic input in mammals, or octopamine (OA) in insects. To understand the circuit mechanisms of this signaling, we characterized the function of two OA neurons, sVUM1 neurons, that originate in the subesophageal zone (SEZ) and target the input region of the memory center, the mushroom body (MB) calyx, in larval We found that sVUM1 neurons target multiple neurons, including olfactory projection neurons (PNs), the inhibitory neuron APL, and a pair of extrinsic output neurons, but relatively few mushroom body intrinsic neurons, Kenyon cells. PN terminals carried the OA receptor Oamb, a α1-adrenergic receptor ortholog. Using an odor discrimination learning paradigm, we showed that optogenetic activation of OA neurons compromised discrimination of similar odors but not learning ability. Our results suggest that sVUM1 neurons modify odor representations via multiple extrinsic inputs at the sensory input area to the MB olfactory learning circuit.
感知信号的辨别对于生物体在特定行为情境中形成和提取相关记忆至关重要。在哺乳动物中，通过去甲肾上腺素输入或昆虫中的章鱼胺 (OA) 携带的信号，感知表示被动态地修改，从而促进了行为的上下文相关选择。为了理解这种信号转导的电路机制，我们描述了两个 OA 神经元 sVUM1 神经元的功能，这些神经元起源于食管下区 (SEZ)，并靶向记忆中心的输入区域，即蘑菇体 (MB) 蕈形体。我们发现 sVUM1 神经元靶向多个神经元，包括嗅觉投射神经元 (PNs)、抑制性神经元 APL 和一对外在输出神经元，但相对较少的蘑菇体内在神经元，即肯尼恩细胞。PN 末梢携带 OA 受体 Oamb，一种α1-肾上腺素能受体的同源物。使用气味辨别学习范式，我们表明光遗传学激活 OA 神经元会损害相似气味的辨别能力，但不会影响学习能力。我们的结果表明，sVUM1 神经元通过 MB 嗅觉学习电路的感觉输入区域的多个外在输入来修饰气味表示。
