High resolution optical approaches to study dendritic signaling

为了了解大脑是如何工作的，我们必须了解它的组成部分，脑细胞，特别是神经元，如何传递信息和交流。神经传递的主要场所是数十亿个微小的突触。通过识别突触的分子组成以及突触信号的电化学性质，在理解突触传递方面取得了很大进展。然而，对于这些成分和信号中的大多数，关于它们在神经传递过程中如何运作和相互作用仍然是未知的。为了充分了解突触的工作原理，我们需要解析它们的分子组成和活神经回路中的基本信号，并在与神经传递相关的长度和时间尺度上对其进行监测。 由于突触是如此微小（<1/1000毫米），我们必须推动我们的显微镜的空间分辨率的极限。由于神经元的通信是如此之快（毫秒），我们也必须推动我们的成像速度更快。因此，我们的努力集中在显微镜方法的优化，以了解神经元内的分子如何响应和翻译神经元的电活动。 我们的方法包括从大鼠海马神经元培养的准备。我们在这些神经元中引入基因，我们修改这些基因以编码含有荧光标记的突触蛋白。然后，我们使用先进的光学显微镜，其中大部分是在实验室组装的，使用特殊的激光和光学透镜，来跟踪神经元及其突触内部的荧光信号，因为它们在交流。我们还使用其他类型的荧光探针，如纳米晶体和有机探针。我们的主要问题是神经元如何将其电活动编码为细胞内的生化活动。通过这个神经光子学研究计划，我们希望有助于提高我们对神经元用于通信的基本机制的理解，并调整其通信模式以支持学习和记忆。我们的计划是在光学和神经生物学之间的接口。它培养了新一代高素质的生物光子学人才，并得到了NSERC生物光子学培训计划的支持。

To understand how the brain works, we must learn how its components, the brain cells and particularly the neurons, transmit information and communicate. The main sites of neurotransmission are the billions of tiny synapses. Great progress toward understanding synaptic transmission has been made through the identification of the molecular components of synapses as well as the electrochemical nature of synaptic signals. However, for the majority of these components and signals, much remains unknown about how they operate and interact during neurotransmission. To fully understand how synapses work, we need to resolve their molecular components and elementary signals within living neural circuits and to monitor them at length and time scales relevant to neurotransmission. Because synapses are so tiny (<1/1000 of a millimeter), we must push the limits of spatial resolution of our microscopes. Because neuronal communication is so rapid (milliseconds), we must also push our imaging to fast speed. Thus our efforts are focussed on the optimization of microscopy methods to understand how molecules inside neurons respond to and translate the electrical activity of neurons. Our approaches involve the preparation of cultures of neurons from the rat hippocampus. We introduce in these neurons genes which we modify to encode synaptic proteins containing a fluorescent tag. We then use advanced optical microscopes, most of which assembled in the laboratory, using special lasers and optical lenses, to track the fluorescent signals inside the neurons and their synapses as they communicate. We also use other types of fluorescent probes, such as nanocrystals and organic probes. Our main question is how do neurons encode their electrical activity into biochemical activity intracellularly. Through this Neurophotonics Research Program we hope to contribute to improve our understanding of the fundamental mechanisms that neurons use to communicate and to adapt their modes of communication to support learning and memory. Our Program is at the interface between Optics and Neurobiology. It trains a new generation of Highly Qualified Personel in Biophotonics, supported by an NSERC Training Program in Biophotonics.