Optical probing of inhibitory circuits in visual cortex

研究微电路对于理解神经系统的功能似乎是必不可少的。在新皮层中，由于这种结构的复杂性及其带来的技术挑战，潜在的微电路在很大程度上仍然未知。这种复杂性的一个主要部分与抑制性中间神经元网络有关，它们在形态和生理特性上表现出极其多样化，然而，可以论证的是，它们可能是皮层处理的关键。研究皮层神经元突触连通性的标准方法是在切片中对相邻的神经元对进行双重记录，以找到连接的神经元对。最近，尤斯特博士的实验室开发了一种光学探测方法，可以直接揭示兴奋性突触回路。然而，这种方法依赖于突触兴奋，因此不能应用于抑制回路的研究。我的建议的目标是：i)使用传统的双重记录识别小鼠视觉皮层中的抑制回路；ii)开发一种光学探测方法来揭示抑制性突触目标。具体来说，我想用光学方法检测第5层小鼠初级视觉皮层中两种主要类型的中间神经元（FS和LTS细胞）的突触后神经元。我将使用突触后[C1]变化的双光子成像，低[CI]- acsf实验，在中间神经元激活可能使突触后目标沉默的条件下的图像处理方案，以及相关或反相关自发放电的检测。该微电路的研究可以揭示这些神经元在控制视觉关键时期和弱视相关发病机制中的重要作用。

The study of microcircuitry appears essential for the understanding the function of the nervous system. In the neocortex, the underlying microcircuitry remains largely unknown, due to the complexity of this structure and the technical challenges it creates. A major part of this complexity relates to the networks of inhibitory interneurons which appear extremely diverse in morphological and physiological properties, yet, arguably, could hold the key to cortical processing. The standard method to study synaptic connectivity of cortical neurons has been to perform dual recordings from closely neighboring pairs of neurons in slices in order to find connected pairs. Recently, Dr. Yuste's laboratory has developed an optical probing method that directly reveals excitatory synaptic circuits. This approach, however, relies on synaptic excitation and therefore cannot be applied to the study of inhibitory circuits. The goals of my proposal are to i) identify inhibitory circuits in mouse visual cortex using traditional dual recordings and ii) develop an optical probing method that reveals inhibitory synaptic targets. Specifically, I want to optically detect the neurons that are post-synaptic to two major types of interneurons (FS and LTS cells) n layer 5 mouse primary visual cortex. I will use two-photon imaging of post-synaptic [C1]-changes, low [CI]-ACSF experiments, image processing protocols under conditions where the activation of interneurons may silence post- synaptic targets and detection of correlated or anti-correlated spontaneous firing. The study of this microcircuitry can reveal the important role of these neurons in controlling critical periods for vision and related pathogenesis of ambiliopia.