Changes Of Local Field Potentials In M1 And PPC Underlying The Specific Behavior In The Rat

Brain Computer Interface (BCI) is a direct and new information communication system between the human brain and a computer or other electronic devices, and now it has become one of the hottest interdisciplinary topics between neuroscience and Information Engineering. One of the key technologies of BCI is to understand the corresponding electrical activity of the brain underlying the certain behaviors and decodes it into the computer instructions. And an important part of BCI research is the analysis of local field potentials (LFPs) of the cerebral cortex which is associated with movements underlying freedom behavioral activities. Moreover,it could be used to detect and analyze other behavioral and cognitive function for promoting the deepening research of the brain.A self-made specific micro-electrode and behavior synchronous device were devised to record the changes of LFPs from the primary motor cortex (M1) and posterior parietal cortex (PPC) of rats when they were catching in this study. Multichannel physiological signals collecting and processing systems and high impedance micro-power amplifier simultaneously. Then, the collected LFPs was processed off-line and analyzed by the MATLAB software to understand the changes of the LFPs and the association of M1 and PPC underlying the specific behavior in rats. The study laid a foundation for the future BCI research based on the LFPs. This experimental study was divided into two parts:1. Changes of LFPs in M1 underlying the specific behavior in the ratThe LFPs underlying specific behavior was recorded from M1 with the self-made single channel micro-electrodes and analyzed by MATLAB in this part. During the experiment, the specific behavior was divided into four periods according the changes of the recorded LFPs and the changes of the specific behavior recorded simultaneously in rats. And the four periods were named respectively: prophase of catching period, planning period, catching period and the completion period. Then several methods were used for the analysis of the LFPs, such as time domain analysis, frequency domain analysis and time-frequency analysis. According to the time domain analysis, the LFPs of prophase of catching period showed a clusters of high amplitude electrical activity. And the activities of planning period showed significant transient low amplitude. Then there was an obvious increase with the amplitude during the catching period. In this period, the amplitude of the LFPs had a significant differences comparing with the planning period. However, the amplitude of the LFPs mainly appeared some degree of decrease in the following completion period. According to the frequency domain analysis and the time-frequency analysis, the frequency of electrical activities in the four periods was not the same. They were above 100Hz, 30-100Hz, 14-30Hz and 14-30Hz respectively in order respectively. The energy of spectrogram and power distribution in the catching period was significantly stronger than prophase of catching period, planning period and completion period. From the analysis of power spectral density based on Welch Transformation, the strongest PSD distributed mainly in the 14-30Hz frequency range during the specific behavior. And it was consistent with the above results. The results suggested that the LFPs which was caused by different behavior from a large number of movement-related neurons of M1 during the specific behavior in the process of catching played an important part in the "code" guiding role in rats. And the results demonstrated that the LFPs of M1 may provide a feasibility to discriminate the motor behavior of forelimb.2. Correlation of LFPs in M1 and PPC underlying the specific behavior in the ratPrevious studies suggested that PPC was associated with the formation of movements planning during vision participating. The changes of LFPs of M1 and PPC were studied with a self-made multi-channels micro-electrode during the specific behavior of catching in rats in this part simultaneously. Then the correlation of the double LFPs was studied with several methods, such as signal comparison, phase analysis, cross-correlation and so on. The results showed that the LFPs recorded from M1 and PPC during the process of the rats'catching emerged certain regularity changes. There was no difference between the LFPs of M1 and PPC. However,these two pieces of LFPs appeared significant difference from the phase analysis. The results suggested that the LFPs recorded from M1 and PPC presented certain differences in the time of their occurrence. Moreover, the emergence of LFPs which were recorded from PPC were earlier than the one from M1 according to the cross-correlation of the double signals. In this way, the lags calculated between the two signals were 5.45士2.68ms. And it further confirmed the results of phase analysis. The results showed that there were some correlation between the two signals which were recorded from M1 and PPC during the process of animal's specific behavior. And the changes of LFPs of PPC were earlier than M1. The results suggested that PPC planned and controlled the activities of M1.Conclusion: The LFPs of M1 played a very important role in the controlling of the specific movement behavior and PPC played a "planning" and "controlling" role in the process of the task.