Study Based On LFP Used In Tuning Characteristics Of Neuronal Receptive Field

The pattern of encodingvisual information in primary visual cortex has been the focus of the study of neurophysiology.and the receptive field tuning characteristics is the basic of the study in visual information processing mechanism.The local field potential of the low frequency and the spike of high frequency are two important signals obtained from neuron receptive field of the primary visual cortex.animal visual processing mechanism is a very complex processing.how to extract more features which is related with the visual stimulus from these two signals is the basis for subsequent visual analysis, the current research are mostly based on the spike firing rate, but spike firing rate is a discrete sequence which is easily disturbed by the noise, so in the condition of low SNR. the results obtained by spike firing rate is low reliable;Local field potential is a continuous signal which can be divided into different rhythm waveform, different rhythm wave contain the information of visual stimulus or the state information, SNR of the rhythm wave is higher than spike, therefore, under low SNR conditions, from the point of view of the local field potential, finding the characteristics related with visual stimulation becomes particularly important.This thesis use LE(long evens) rats as object of study, and use Microprobe microelectrode record spike signal and local field potential signal in primary visual cortex at the same time,and then we design sinusoidal grating visual stimuli orthogonal test,choosing the space frequency,time frequency and orientations of the grating as the three experimental factors.comparative study spikes and local field potential for the neuron receptive field tuning characteristics, details are as follows:(1) According to the purpose and the research object,using sinusoidal gratings as visual stimulus of neuronal receptive fields,we design Three factors of orthogonal test.record spike and local field potential of primary visual cortex of rats using microelectrodes at the same time.(2) Analysis of differences in local field potential signal before and after stimulation based on the frequency domain coherence combined with Pwelch power spectrum estimation,and find the gamma-band is the feature band of visual stimulation.(3) Select the appropriate wavelet function, extract feature band of the local field potential using the wavelet transform, analysis energy distribution of the band with different visual stimuli and then further confirmed that the energy distribution of the feature band code stimulus information.(4) Comparative Study the tuning characteristics based on spike firing rate and local field potential under different visual stimulation parameters, find the local field potential can achieve a similar effect with spike firing rate.(5) For neuronal signals susceptible to noise,we study antiinterference performance of oritentations tuning characteristics and spatial frequency characteristics based on spikes and local field potential and found that local field potential is better than spike.