Research Of Phase Synchronization Information Coding Of The Local Field Potential In Primary Visual Cortex Of Rat

The animal visual system is the main system of external information perception, almost all of information is processed in the primary visual cortex. The local field potential is an important carrier of outside stimulus information of neurons. It highlights the cooperatives of the neurons in the neural network and is characterized by slow potential changes. Synergistic effect of the primary visual cortex neuron network is the basic function of visual information processing. The phase feature of the local field potential is an important measure of stimulus information expression. The local field potential phase synchronization is of great significance to explain the transformation rules and integration mechanisms of neuronal information in the brain cortex.In the paper the Long Evans rats were used as the experimental object. The local field potentials were obtained by a multi-electrode array signal acquisition system under12orientations full screen grating as stimulus images. Effective extraction of the raw local field potential signals obtained in experiment, the local field potential phase synchronization coding characteristics of stimulation were analyzed from two aspects of single-channel and multi-channel. The main contents are as follows:(1) The extraction of local field potential. After the analysis of noise characteristics in LFP signals, the original LFP are processed by independent component analysis, providing pure local field potential signal for the following study.(2) Research on phase synchronization information coding of local field potential in single channel. Firstly, the instantaneous phase of LFP obtained before and after same stimulation in different time were extracted by Hilbert transform in single channel, phase locking value before and after stimulation and the difference were calculated to determine the best stimulus orientation toward LFP response; then the LFP under best stimulus orientation was decomposed by the EEMD multi— mode decomposition and the selections of all mode functions for the best stimulus orientation were analyzed based on the analysis of the mode mixing problem and ensuring of effective modes of EEMD. And the optimal frequency range was determined by multiple channel data analysis. Finally the results of the phase synchronization information coding of LFP and spike firing rate coding were compared(3) Research on phase synchronization information coding of local field potential in multi-channel. Firstly, the reference channel was selected. The phase locking value of LFP before and after same stimulation in same time between the rest of the channels and the reference channel was calculated. The optimal orientation was determined. Then the LFPs under the best orientation were decomposed by EEMD. The orientation selectivity for the stimulus was analyzed with the mode functions. The optimal frequency response range was determined using the static data on LE rats. Finally, the phase synchronization information coding characteristics are analyzed with the orientation tuning curves under all orientations. The coding results of the optimum frequency band phase synchronization information coded with methods of EEMD, EMD and. the low-pass filter extraction were compared.