Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.
Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.
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DOI：
10.1002/nbm.1724
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发表时间：
2012-01
影响因子：
2.9
通讯作者：
Hu, Xiaoping P.
中科院分区：
文献类型：
--
作者：
Poplawsky, Alexander J.;Dingledine, Raymond;Hu, Xiaoping P.
功能磁共振成像（fMRI）通过检测与大脑激活后血流动力学反应相关的信号变化，间接测量神经活动。为了减轻与功能磁共振成像相关的时间和空间特异性问题，已经进行了许多尝试，用MRI直接检测神经磁场（NMFs），但迄今为止提供了相互矛盾的结果。在本研究中，我们采用自由感应衰减（FID）的方法，以0.32 ms的采样间隔检测蚯蚓（Lumbricus terrestris）中间巨纤维的轴突NMFs。将蚯蚓神经索与脉管系统分离，在动作电位产生的阈值处进行刺激。在刺激后不久获得FIDs，同时进行的场电位记录确定了单诱发动作电位的存在或不存在。当刺激没有引起动作电位时获得的fid被总结为背景。减去背景的FID相位呈现出系统性的变化，在与动作电位的时间相对应的时刻出现了[-1.2±0.3]×10-5弧度的峰值相位差。此外，我们使用体积导体模型计算了由于模拟动作电位而导致的FID大小和相位的可能变化。测量的相位差在幅值和时间特性上与理论预测相吻合。这项研究为使用磁共振从诱发动作电位直接检测磁场提供了第一个证据。
Functional MRI (fMRI) indirectly measures neural activity by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In the present study, we used magnetic resonance to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free-induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of [-1.2 ± 0.3] ×10-5 radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase due to a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using magnetic resonance.
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影响因子：
2.5
作者：
Liston, AD;Salek-Haddadi, A;Lemieux, L
通讯作者：
Lemieux, L
影响因子：
2.5
作者：
Chow, Li Sze;Cook, Greg G.;Paley, Martyn N. J.
通讯作者：
Paley, Martyn N. J.
影响因子：
5.7
作者：
Chu, RN;de Zwart, JA;Duyn, JH
通讯作者：
Duyn, JH
影响因子：
2.5
作者：
KAO, CY;GRUNDFEST, H
通讯作者：
GRUNDFEST, H
DOI：
10.1098/rspb.1946.0005
发表时间：
1946-01-01
期刊：
PROCEEDINGS OF THE ROYAL SOCIETY SERIES B-BIOLOGICAL SCIENCES
影响因子：
--
作者：
RUSHTON, WAH
通讯作者：
RUSHTON, WAH