Research Of The Temporal-Spatial Frequency Response Characteristics In Primary Visual Cortex Of Rat

After long-term evolution of the nature, the animal visual system has evolved into one information processing system, which has the most perfect function and outstanding mechanism. Above80%of the outside world information are obtained by vision. Almost all the visual information from the retina is handled in the primary visual cortex. Therefore, it is of great significance to deeply study the response characteristics of the primary visual coetex. Orientation selectivity is thought to be one of the most important characteristics of neurons in the primary visual cortex, while the temporal frequency and spatial frequency are also basic features of the visual stimulus, so it is worthy of further research to study the spatio-temporal frequency response characteristics, which would be helpful in understanding the mechanisums of visual information processing and drive the development of Brain-computer interfaces, image processing, and rehabilitation engineering.In this paper, experiments were designed to collect electrical signals in the primary visual cortex of rats under visual stimulus, analyzed the spatio-temporal frequency response characteristics based on Spikes and LFPs (Local field potencials) separately, Details are as follows:First, experimental design. Including the establishment of the experimental platform, the design of the surgical operation scheme, and the development of the visual stimululation scheme. All of these works would provide neurophysiological support for the research of response characteristics to different grating stilulus in rats’ primary visual cortex.Second, study the spatio-temporal frequency response characteristics of rats’ primaty visual cortex based on Spikes. Firstly, Multi-electrode Array(MEA) was used to obtain the electrical signals of rat primary visual cortex under sinusoidal gratings of different spatial and temporal frequencies, Spike detection and classification was processed. Secondly, the tuning characteristics of neurons was analyzed by statistics of Spikes to different stimulations. And then, the orthogonal experiment was ananlyzed based on firing rate, according to the analysis of dynamic firing rate under different stimulus, the different dynamic characteristics of neurons were understood, based on this, Gauss fitting was used to fit the probability distribution of firing rate, and the features of probability distribution was analyzed. At last, the spatio-temporal response characteristics of neurons were analyzed to orthogonal experiments.Third, analyze the spatio-temporal frequency response characteristics of rats’ primaty visual cortex based on LFPs. First of all, pretreatment was processed to LFPs, and wavelet analysis was used to understand the time-frequency characteristics of LFPs. And then the Wavelet Packet Entropy(WPE) of LFPs were calculated to study the tuning characteristics of cortical response to stimulations. And then, the orthogonal experiment was ananlyzed based on WPE, Gauss fitting was used to fit the probability distribution of WPE, and the features of probability distribution was analyzed. The response characteristic of spatio-temporal frequency were analyzed to orthogonal experimental data. Finally, the optimal spatial frequency of rats was determined by statistical analysis of a set of experimental data, which can provide reference for further study.