DENDRITIC SIGNALING IN THE OLFACTORY BULB

嗅球中的树突信号传导

• 批准号: 6922875
• 负责人: GRAEME LOWE
• 金额: $ 16.05万
• 依托单位: MONELL CHEMICAL SENSES CENTER
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6922875
• 关键词: GABA receptor; NMDA receptors; action potentials; biological signal transduction; calcium; calcium flux; clathrate; dendrites; fluorimetry; gamma aminobutyrate; glutamate receptor; glutamates; laboratory rat; male; neural information processing; neural inhibition; neural transmission; neuroanatomy; neuroregulation; olfactory lobe; photostimulus; synapses; voltage /patch clamp

The mammalian olfactory system is unrivalled in its ability to detect, identify and discriminate an enormous variety of odor stimuli with exquisite sensitivity. What neural processing mechanisms underlie this remarkable feat? Odor information is relayed to the brain as spatially patterned activity in the glomerular layer of the olfactory bulb. The bulb transforms these patterns into the coordinated firing of ensembles of output neurons, the mitral cells. The long term objective of this research is to determine the dendritic and synaptic mechanisms that shape these firing patterns. Mitral cells radiate long secondary dendrites which are coupled, via reciprocal synapses, to granule cells. The deceptively simple structure of these dendrites belies their complex, multifunctional roles in signal processing. The aim of this project is to analyze the spatial organization of signaling in these dendrites. Our working model divides the dendrite into two dynamic domains: a proximal somatodendritic domain for temporal coding, and a distal dendritic domain for spatial coding. In the proximal domain, action potential timing is postulated to be controlled by: (i) integration of GABAergic input from reciprocal synapses, and (ii) modulation of intrinsic conductances by glutamate autoreceptors. In the distal domain, backpropagating action potentials activate calcium channels, triggering dendrodendritic transmission. It is postulated that spatial patterns of transmission depend on: (i) local modulation of action potentials, and (ii) differential distribution of calcium channels and AMPA or NMDA-type glutamate autoreceptors. We propose that calcium signaling is under dual feedback control: positive feedback amplification by NMDA receptors is balanced against negative feedback inhibition by GABA receptors. These mechanisms determine the spatiotemporal patterns of neurotransmission and electrical activity in the olfactory bulb that are central to odor information coding and processing. We analyze these mechanisms by combining brain slice patch-clamp, optical imaging, and laser photostimulation using caged compounds. This work has broad significance for understanding the control of dendritic transmission by patterns of electrical and calcium signaling, and may provide fundamental insights into the cellular bases of CNS pathologies involving the excitatory- inhibitory control of neural network activity, such as epilepsy.

哺乳动物的嗅觉系统在检测、识别和区分种类繁多的气味刺激方面具有无与伦比的能力，并且具有极高的灵敏度。 这一非凡壮举背后的神经处理机制是什么？ 气味信息作为嗅球肾小球层的空间模式活动传递到大脑。 灯泡将这些模式转化为输出神经元（二尖瓣细胞）群的协调放电。 这项研究的长期目标是确定形成这些放电模式的树突和突触机制。 二尖瓣细胞放射出长的次级树突，这些树突通过相互突触与颗粒细胞耦合。 这些树突看似简单的结构掩盖了它们在信号处理中复杂的多功能作用。 该项目的目的是分析这些树突中信号传导的空间组织。 我们的工作模型将树突分为两个动态域：用于时间编码的近端体树突域和用于空间编码的远端树突域。 在近端域，动作电位计时被认为是由以下因素控制的：（i）来自相互突触的 GABA 能输入的整合，以及（ii）谷氨酸自身受体对内在电导的调节。 在远端区域，反向传播动作电位激活钙通道，触发树突传递。 据推测，传输的空间模式取决于：(i) 动作电位的局部调节，以及 (ii) 钙通道和 AMPA 或 NMDA 型谷氨酸自身受体的差异分布。 我们认为钙信号传导受到双重反馈控制：NMDA 受体的正反馈放大与 GABA 受体的负反馈抑制相平衡。 这些机制决定了嗅球神经传递和电活动的时空模式，而嗅球是气味信息编码和处理的核心。 我们通过结合脑切片膜片钳、光学成像和使用笼状化合物的激光光刺激来分析这些机制。 这项工作对于理解电信号和钙信号传导模式对树突传递的控制具有广泛的意义，并且可能为涉及神经网络活动的兴奋-抑制控制的中枢神经系统病理学的细胞基础提供基本的见解，例如癫痫。