Plasticity and function of backpropagating Action Potential mediated calcium signals in dendritic spines

神经元阈上激活后的动作电位（AP）传播回树突树。反向传播动作电位（bAP）介导的树突节段和相邻棘的去极化导致电压门控钙通道介导的流入树突和棘。这些全局钙信号比局部突触介导的钙瞬变激活更多数量的棘，但其功能知之甚少。在内侧内嗅皮层第二层星状细胞，我们将进一步研究的可能性，这些（bAP）介导的钙瞬变（bAPCaTs）是自我调节，可塑性事件与突触传递的影响。将研究bAPCaTs的活性依赖性增强的诱导和表达机制以及它们对突触传递和电路功能的功能意义。将使用组合的全细胞膜片钳记录和双光子钙成像与低亲和力钙指示剂（fluo4FF）进行研究。该指标的低缓冲能力将使我们能够在监测bAPCaTs的同时研究其生物学效应。将Alexa 594添加到记录溶液中，来自单独红色通道的形态数据允许将功能数据与脊柱形态测量相结合。双光子谷氨酸释放将被应用于研究bAPCaTs和突触传递的相互作用在单棘。

Action potentials (APs) following suprathreshold activation of neurons propagate back into the dendritic tree. Backpropagating Action Potential (bAP)-mediated depolarization of dendritic segments and adjacent spines results in voltage-gated calcium channel mediated influx into dendrites and spines. These global calcium signals activate a much larger number of spines than local synaptically mediated calcium transients, but their function is poorly understood. In medial entorhinal cortex layer II stellate cells, we will further examine the possibility that these (bAP)-mediated calcium transients (bAPCaTs) are self-regulatory, plastic events with an impact on synaptic transmission. Mechanisms underlying induction and expression of activity-dependent boosting of bAPCaTs as well as their functional implications for synaptic transmission and circuit function will be studied. Investigations will be performed using combined whole-cell patch clamp recordings and two-photon calcium imaging with low affinity calcium indicators (fluo4FF). The low buffer capacity of this indicator will enable us to study biological effects of bAPCaTs while monitoring them. Adding Alexa 594 to the recording soution, morphological data from a separate red channel permits combination of functional data with spine morphometry. Two-photon glutamate uncaging will be applied to study the interaction of bAPCaTs and synaptic transmission in single spines.