Carrubba S, Frilot C, Chesson A L, Marino A A
Department of Orthopedic Surgery, Louisiana State University Health Sciences Center, P.O. Box 33932, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
Neuroscience. 2007 Jan 5;144(1):356-67. doi: 10.1016/j.neuroscience.2006.08.068. Epub 2006 Oct 25.
Human subjects respond to low-intensity electric and magnetic fields. If the ability to do so were a form of sensory transduction, one would expect that fields could trigger evoked potentials, as do other sensory stimuli. We tested this hypothesis by examining electroencephalograms from 17 subjects for the presence of evoked potentials caused by the onset and by the offset of 2 G, 60 Hz (a field strength comparable to that in the general environment). Both linear (time averaging) and nonlinear (recurrence analysis) methods of data analysis were employed to permit an assessment of the dynamical nature of the stimulus/response relationship. Using the method of recurrence analysis, magnetosensory evoked potentials (MEPs) in the signals from occipital derivations were found in 16 of the subjects (P<0.05 for each subject). The potentials occurred 109-454 ms after stimulus application, depending on the subject, and were triggered by onset of the field, offset of the field, or both. Using the method of time averaging, no MEPs were detected. MEPs in the signals from the central and parietal electrodes were found in most subjects using recurrence analysis, but no MEPs were detected using time averaging. The occurrence of MEPs in response to a weak magnetic field suggested the existence of a human magnetic sense. In distinction to the evoked potentials ordinarily studied, MEPs were nonlinearly related to the stimulus as evidenced by the need to employ a nonlinear method to detect the responses.
人类受试者会对低强度电场和磁场作出反应。如果这种反应能力是一种感觉转导形式，那么人们会预期这些场能够像其他感觉刺激一样引发诱发电位。我们通过检查17名受试者的脑电图，来测试这一假设，以确定是否存在由2 G、60 Hz（一种与一般环境中的场强相当的场强）的开启和关闭所引起的诱发电位。我们采用了线性（时间平均）和非线性（递归分析）两种数据分析方法，以便对刺激/反应关系的动态性质进行评估。使用递归分析方法，在16名受试者的枕部导联信号中发现了磁感觉诱发电位（MEP）（每名受试者P<0.05）。根据受试者的不同，这些电位在刺激施加后109 - 454毫秒出现，并且由场的开启、场的关闭或两者触发。使用时间平均方法，未检测到MEP。使用递归分析，在大多数受试者的中央和顶叶电极信号中发现了MEP，但使用时间平均方法未检测到MEP。对弱磁场作出反应而出现的MEP表明人类存在磁感。与通常研究的诱发电位不同，MEP与刺激呈非线性关系，这一点从需要采用非线性方法来检测反应中得到证明。
