Assessing sensory versus optogenetic network activation by combining (o)fMRI with optical Ca2+ recordings.
Assessing sensory versus optogenetic network activation by combining (o)fMRI with optical Ca2+ recordings.
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DOI：
10.1177/0271678x15619428
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发表时间：
2016-11
期刊：
影响因子：
--
通讯作者：
Stroh A
中科院分区：
文献类型：
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作者：
Schmid F;Wachsmuth L;Schwalm M;Prouvot PH;Jubal ER;Fois C;Pramanik G;Zimmer C;Faber C;Stroh A
皮层中感觉输入的编码以稀疏神经元网络激活为特征。光遗传学刺激先前已与fMRI（ofMRI）结合以探测功能网络。然而，对于感官驱动的稀疏网络激活的定量光遗传学探测，需要探索感官和光遗传学网络激活之间的相似性水平。在这里，我们补充ofMRI与光纤为基础的人口Ca 2+记录的区域特异性读出大鼠大脑中的神经元尖峰活动。比较Ca 2+响应的血氧水平依赖的信号后，感觉刺激与增加频率显示适应的Ca 2+瞬变对比增加的血氧水平依赖的反应，表明光学记录传达互补的信息，神经元网络的活动，以相应的血液动力学反应。为了研究光遗传学和感觉激活的相似性，我们量化了表达通道视紫红质-2的细胞的密度并模拟了组织中的光传播。我们估计了光遗传学刺激的神经元的有效照明体积和数量，这表明稀疏激活。在功能水平上，无论是感觉或光遗传学刺激，我们检测到单峰短潜伏期初级钙离子反应具有相似的幅度，并发现血氧水平依赖性反应显示出类似的时间进程。这些数据表明，ofMRI可以作为一个有代表性的模型功能脑映射。
Encoding of sensory inputs in the cortex is characterized by sparse neuronal network activation. Optogenetic stimulation has previously been combined with fMRI (ofMRI) to probe functional networks. However, for a quantitative optogenetic probing of sensory-driven sparse network activation, the level of similarity between sensory and optogenetic network activation needs to be explored. Here, we complement ofMRI with optic fiber-based population Ca2+ recordings for a region-specific readout of neuronal spiking activity in rat brain. Comparing Ca2+ responses to the blood oxygenation level-dependent signal upon sensory stimulation with increasing frequencies showed adaptation of Ca2+ transients contrasted by an increase of blood oxygenation level-dependent responses, indicating that the optical recordings convey complementary information on neuronal network activity to the corresponding hemodynamic response. To study the similarity of optogenetic and sensory activation, we quantified the density of cells expressing channelrhodopsin-2 and modeled light propagation in the tissue. We estimated the effectively illuminated volume and numbers of optogenetically stimulated neurons, being indicative of sparse activation. At the functional level, upon either sensory or optogenetic stimulation we detected single-peak short-latency primary Ca2+ responses with similar amplitudes and found that blood oxygenation level-dependent responses showed similar time courses. These data suggest that ofMRI can serve as a representative model for functional brain mapping.