人脑白质与脑灰质α色散和β色散过渡区分析

Analysis of Transition Zones Between α and β Dispersions in Brain White Matter and Grey Matter

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 α and β dispersions occurred in brain white and grey matter and the dielectric properties in transition zone. Methods The Cole-Cole model was used to calculate the increment of dielectric constant, and the frequencies at which α and β dispersions occurred were estimated. The authors investigated the characteristics of α and β dispersion in the transitibn zone by Cole-Cole circles and the corresponding polarization mechanism. Results The α dispersion of brain white and grey matter occurred from over 10 Hz to several kHz while the fl dispersion began with hundreds of Hz. Conclusion The frequency of the a and fl dispersions in the white matter occur less than that in the grey matter. The frequency width of a dispersion in the white matter is narrower than that of the grey matter. The width of transition zone in the white matter is less than that of the grey matter. The α dispersion is dominant factor in the two transition zones and the corresponding polarization mechanism is ionic polarization.