CRCNS: Input/Output Characterization of the Antennal Lobe of the Drosophila

描述(由申请人提供)：本提案中描述的果蝇触角叶的I/O特征是通过两个关键的使能工具实现的：(I)投射神经元及其支配的肾小球的遗传识别；(Ii)触角叶气味信号处理的多输入/多输出(MIMO)建模。这两个工具都是作者最近提出的。在MIMO模型中，天线波瓣及其功能通过传递函数矩阵来描述。我们的目标是识别传输矩阵，并用相同的矩阵在计算机上构建一个电路图，能够预测天线瓣的时空I/O动态。MIMO模型作为理论家和实验者之间的共同语言，并提供了一个框架，可以在其中设计相关问题和设计实验来回答这些问题。例如，是否存在表现出较低复杂性的相同的天线瓣I/O特征？我们将通过(I)分析表达相同感受器的任意嗅觉感觉神经元子集对气味信息的表征，以及(Ii)研究这些神经元之间的空间滤波方法作为气味信号处理的模型，来研究这种特征。通过对苍蝇嗅觉系统的遗传操作，气味感受器将在连接到指定肾小球的嗅觉感觉神经元中表达。通过沉默大部分剩余的OSN，这些肾小球将有效地与触角叶的其余部分隔离。这将为我们研究苍蝇触角叶的I/O特性提供一个在体内的实验平台。该平台将使我们第一次能够从功能上描述支配同一肾小球的所有单独的投射神经元。我们将调查它们是否在生物物理上是等价的，以及它们是否携带相同的气味信息。我们还将把它们的形象描述为活动OSN数量的函数。我们将提取单个肾小球和从触角叶其余部分分离的2个肾小球网络的传输矩阵。我们计划定量地描述局部/投射神经元对同一肾小球内传递函数的抑制和反馈。我们还计划测量抑制和反馈对其他肾小球的影响。阐明触角叶的气味信号处理可以揭示治疗嗅觉障碍的方法。它还可以揭示神经编码在其他感觉系统中的基本机制。

DESCRIPTION (provided by applicant): The I/O characterization of the Drosophila antennal lobe described in this proposal is made possible by 2 key enabling tools (i) the genetic identification of the projection neurons and the glomeruli they innervate and, (ii) multi-input/multi-output (MIMO) modeling of odor signal processing in the antennal lobe. Both tools have recently been advanced by the authors. The antennal lobe and its function are described in the MIMO model by a transfer function matrix. Our goal is to identify the transfer matrix and construct in silico a circuit diagram with the same matrix that is capable of predicting the spatio-temporal I/O dynamics of the antennal lobe. The MIMO model serves as a common language between theorists and experimentalists, and provides a framework within which to devise relevant questions and design experiments to answer those questions. For example, are there equivalent I/O characterizations of the antennal lobe that exhibit a lower complexity? We shall investigate such characterizations by (i) analyzing the representation of odor information by an arbitrary subset of olfactory sensory neurons expressing the same receptor, and (ii) studying spatial filtering methods among these neurons as a model of odor signal processing. Through genetic manipulation of the fly olfactory system, odor receptors will be expressed in olfactory sensory neurons connected to designated glomeruli. By silencing most of the remaining OSNs, these glomeruli will be effectively isolated from the rest of the antennal lobe. This will provide us with an ' in-vivo experimental platform' for investigating the I/O characteristics of the fly antennal lobe. The platform will enable us for the first time to functionally characterize all individual projection neurons innervating the same glomerulus. We shall investigate whether they are biophysically equivalent and whether they carry equivalent odor information. We will also characterize their image as a function of the number of active OSNs. We will extract the transfer matrix of a single glomerulus and of a network of 2 glomeruli isolated from the rest of the antennal lobe. We plan to quantitatively characterize the inhibition and feedback induced by the local/projection neurons on the transfer function within the same glomerulus. We also plan to measure what effect inhibition and feedback have on other glomeruli. Elucidation of odor signal processing in the antennal lobe could reveal methods of treatment of olfactory deficits. It could also reveal fundamental mechanisms of neural coding in other sensory systems.