Orientation Selectivity Analysis Of Macaque Visual Cortex Neurons Based On Spike And LFP

Orientation selectivity plays an important role in pattern perception,but the formation mechanism for orientation selectivity is not clear.The spike and local field potential are two different forms of neural signals in the brain,with different characteristics.Combining the two signals can obtain more abundant information.In this paper,the implanted microelectrode array was used to collect the spike and local field potential signals in V1 and V4 of the macaque visual cortex,and the synchronization relationship between spike and local field potential and between local field potentials under different orientation stimuli was analyzed.This work provides a new method and idea for studying the formation mechanism of neuronal orientation selectivity.First of all,the data collected by the experiment was preprocessed to extract the spike and local field potential signals.The original signal was band-pass filtered with 300-3000 Hz using a Butterworth filter to obtain a high-frequency signal,and then a threshold method was used for spike detection to obtain a spike train issued by a single neuron.The original signal was low-pass filtered using the zero-phase shift digital filter to obtain the local field potential signals of the Alpha and Gamma bands.Secondly,the correlation matrix method was used to analyze the spike and local field potential synchronization of neurons in V1 and V4 of macaques under sinusoidal grating stimulation.It was found that the synchronization between the firing activity of these neurons and local field potential showed a significant orientation selectivity.Combined with the analysis results of the neural firing rate,it was found that the results of different response characteristics studies orientation selectivity were different.Considering the response intensity,the circular variance and the optimal orientation of the neurons in V1 and V4,it can be seen that the spike and local field potential synchronization is more advantageous than spike firing rate when studying neuronal orientation characteristics.Finally,the information transfer between local field potentials in V1 and local field potentials in V4 of macaques was analyzed by the symbolic transfer entropy.It was found that the information transfer changed with the orientation of the grating.Through further analysis,it was found that the transfer entropy strength from the V1 to the V4 was significantly larger than the opposite direction under different orientation stimuli,and the transfer delay time of the V1 to the V4 was significantly smaller than the transfer delay time of the V4 to the V1.In addition,an index for measuring the difference of information transfer between each channel was proposed.It was found that the difference in information transfer between channels in V1 under the preference orientation stimulus was greater than that the difference in information transfer under the non-preference orientation stimulus,while the V4 did not found significant differences.