Imaging Inhibitory Processing in the Superior Colliculus

描述(申请人提供)：上丘中间层内的GABA能抑制电路在产生启动注视方向转移的运动前信号中起着重要作用。然而，这种抑制的时空动力学仍不清楚。我们将使用Clomeleon，一种遗传编码的氯离子指示剂，实时成像氯离子依赖的突触抑制的空间组织。我们已经培育出在中间层的运动前细胞中表达Clomeleon的转基因小鼠。在这些神经元中慢性表达的Clomeleon能够对与激活GABAA受体相关的氯离子通量作出反应。我们建议使用这些Clomeleon小鼠来确定Clomeleon是否足够敏感，以检测通过刺激GABA能通路在运动前细胞中产生的[Cl-]i的变化。为了检验这样一个假设，即控制凝视的区域中运动前细胞的激活会抑制运动前细胞在一个方向上的移动 我们将使用Clomeleon来可视化中间层的抑制的时空分布，这是由该层凝视向量空间地图中的一个区域的活动引起的。这一功能成像CI介导的抑制方法有可能应用于研究大脑任何区域的抑制回路。

DESCRIPTION (provided by applicant): GABAergic inhibitory circuitry within the intermediate layer of the superior colliculus plays an essential role in generating the premotor signals that initiate shifts in the direction of gaze. However, the spatiotemporal dynamics of this inhibition remain unclear. We will use Clomeleon, a genetically-encoded Cl- indicator, to image in real time the spatial organization of Cl- dependent synaptic inhibition. We have produced transgenic mice that express Clomeleon in premotor cells of the intermediate layer. Clomeleon chronically expressed in these neurons is capable of responding to Cl- fluxes associated with activation of GABAA receptors. We propose to use these Clomeleon mice to determine whether Clomeleon is sufficiently sensitive to detect the changes in [Cl-]i that are generated in the premotor cells by stimulation of GABAergic pathways. To test the hypothesis that activation of premotor cells in a region that commands gaze shifts in one direction inhibits the activity of cells in other regions that would command competing gaze shifts toward stimuli in other directions, we will use Clomeleon to visualize the spatiotemporal distribution of inhibition throughout the intermediate layer that is evoked by activity within one region of this layer's spatial map of gaze vectors. This approach of functional imaging CI-mediated inhibition potentially can be applied to the study of inhibitory circuitry in any brain area.