Octopus visual system: a functional MRI model for detecting neuronal electric currents without a blood-oxygen-level-dependent confound.
Octopus visual system: a functional MRI model for detecting neuronal electric currents without a blood-oxygen-level-dependent confound.
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DOI：
10.1002/mrm.25051
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发表时间：
2014-11
影响因子：
3.3
通讯作者：
Gao, Jia-Hong
中科院分区：
文献类型：
--
作者：
Jiang, Xia;Lu, Hanbing;Shigeno, Shuichi;Tan, Li-Hai;Yang, Yihong;Ragsdale, Clifton W.;Gao, Jia-Hong
尽管人们一直致力于检测由神经元放电产生的瞬态磁场，但磁共振成像（MRI）可以测量功能相关信号的结论仍然存在争议。对于神经元电流MRI （nc-MRI）的人体研究，血氧水平依赖性（BOLD）效应仍然是一个无法解决的混淆。对于去除血红蛋白的组织研究，自然感觉刺激是不可能的。本研究探讨了在无bold环境中检测生理诱导的nc-MRI信号的可行性。头足类软体动物章鱼有脊椎动物一样的眼睛，大的视叶（OLs）和不含血红蛋白的血液。用视网膜电图和局部场电位测量章鱼视网膜和OL的视觉诱发电位。在9.4特斯拉进行核磁共振扫描以捕捉这些活动。电生理记录检测到视网膜和OL在体内的强烈反应；然而，在相位0.2°和幅度0.2%的检测阈值下，nc-MRI未能显示任何统计学上显著的信号变化。在解剖眼ol制剂中进行的实验也得到了类似的结果。这些发现在一个大的无血红蛋白的神经系统表明，感觉诱发的神经元磁场太弱，无法用目前的MRI技术直接检测。
Despite the efforts that have been devoted to detecting the transient magnetic fields generated by neuronal firing, the conclusion that a functionally relevant signal can be measured with magnetic resonance imaging (MRI) is still controversial. For human studies of neuronal current MRI (nc-MRI), the blood-oxygen-level-dependent (BOLD) effect remains an irresolvable confound. For tissue studies where hemoglobin is removed, natural sensory stimulation is not possible. This study investigates the feasibility of detecting a physiologically induced nc-MRI signal in vivo in a BOLD-free environment. The cephalopod mollusc Octopus bimaculoides has vertebrate-like eyes, large optic lobes (OLs) and blood that does not contain hemoglobin. Visually evoked potentials were measured in the octopus retina and OL by electroretinogram and local field potential. nc-MRI scans were conducted at 9.4 Tesla to capture these activities. Electrophysiological recording detected strong responses in the retina and OL in vivo; however, nc-MRI failed to demonstrate any statistically significant signal change with a detection threshold of 0.2° for phase and 0.2% for magnitude. Experiments in a dissected eye-OL preparation yielded similar results. These findings in a large hemoglobin-free nervous system suggest that sensory evoked neuronal magnetic fields are too weak for direct detection with current MRI technology.
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影响因子：
2.5
作者：
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通讯作者：
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