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目的研究脑白质和脑灰质α、β色散发生的频率范围及α、β色散过渡区内的介电特性。方法应用Cole-Cole模型通过数值计算得出介电常数增量,以此为据推导α、β过渡区的频域范围;应用ColeCole圆研究过渡区内α和β色散的特点及相应的极化机制。结果脑白质和灰质的α色散始于十几赫兹,终于数千赫兹,β色散起始于几百赫兹。结论脑白质α和β色散开始的频率均低于脑灰质;脑白质α色散频率宽度窄于脑灰质;脑白质的α和β色散过渡区宽度小于脑灰质。两种色散过渡区内均由α色散占主导地位,其对应的极化方式均为离子极化。
Objective To study the frequency range of white matter and gray matter α, β dispersion and the dielectric properties in the α, β dispersion transition region. Methods The Coele-Cole model was used to calculate the dielectric constant increment, which was used to derive the frequency domain of α and β transition region. The ColeCole circle was used to study the characteristics of the α and β dispersions in the transition region and the corresponding polarization mechanism. Results The alpha dispersion of white matter and gray matter starts at ten dozen hertz and finally several thousand hertz with the beta dispersion starting at a few hundred hertz. Conclusions The frequency of α and β dispersions of white matter is lower than that of gray matter. The width of α dispersion of white matter is narrower than that of gray matter. The width of α and β dispersion of white matter is smaller than that of gray matter. Both of the two dispersion transitional regions are dominated by α dispersion, and their corresponding polarization modes are ion polarizations.