Study And Application On The Analysis Model Of Brain Electrical Signal Using By Comsol

The electrical activity in neural network is very important to the research on the brain function and foci localization. The technologies such as in vivo deep brain EEG and iEEG in clinic are custom to be adopted, these recordings sampled by these technologies are local field potentials(LFPs). For example, Theta rhythms(4~12Hz), central in cognition could be derived from the LFPs in a nuclei. Power and phase stability are widely applied, but how two parameters correlate to the electrical feature of biology tissue and neural activity of dipole current generator have been unknown well yet. Here a simulation was done here to address the issue theoretically.At the level of neural network, the theory of equivalent dipole current to explain the mechanism of LFPs generation was generally employed: The LFPs were formed by the volume currents(sum of the volume currents was termed as equivalent dipole current) flowing in the surrounding medium in the extra-cells in the populations of neurons, which were parallel in orientation and quasi-synchronous in time.Here, based on the theoretical implementation of equivalent dipole current, Theta oscillatory FPs(quasi-static and ir-rotational FPs) were calculated by using the FEM in the software of Comsol Multiphysics(FEMLAB); Theta power and phase stability were derived by Hilbert transformation; Theta phase stability was calculated by three methods: Phase preservation index, rose of relative phase and phase sorting by EEGLAB after FFT and iFFT; the influence of activity(amplitude, frequency, phase, time duration and placement) of dipole current and conductivity as well as anisotropy on both of Theta power and Theta phase stability was investigated.The findings are:(1) Theta power of FPs was decreased with the increase of electrical conductivity, and it was not only proportional to the square of amplitude of dipole current, but also was correlated to its location, no relevance to its frequency and phase stability;(2) Reversely, Theta phase stability of FPs was only dependent on that of dipole current, no relevance to other factors.It is concluded that Theta power was related to both the electrical feature of conducting medium and the activity of dipole current; however, Theta phase stability was only dependent on the activity of dipole current. It was implied that Theta power and phase stability might map the neural activity in different manner, both parameters might supply more information than only one in the neural network, this work might be helpful to know the influence of biological tissue on the cognitive rhythms.