Nonlinear Dynamics Analysis Of Orientation Information Modulation Of Non-Classical Receptive Field In Rat’s Primary Visual Cortex

The primary visual cortex(V1) is rats’ important cortex of processing visual information. Rat primary visual cortex neuron’s receptive field was surrounded by the non-classical receptive field, it can produce inhibition or facilitation modulation effect on receptive field response. Receptive field play a key role to distinguish the outline, edges and local characteristics of visual stimuli, is the important foundation of image background segmentation and target identification. Neuron’s response signal has nonlinear dynamics characteristics, nonlinear dynamic characteristics of rats neuron’s spiking activity can reflect the change of rats state and the neural signal modulation mechanism, attracted great attention in the field of neuroscience researchers. Nonlinear dynamic analysis method was used to study nonlinear characteristic of the neuron response signal, can find inner certainty of seemingly random signal, gain more dynamic information, contributes to understanding the nonlinear neural mechanism of visual system to deal with complicated image.In this thesis, LE(Long Evans) rats was chosen as the research object, designed three types of circular grating stimulation mode, the chaotic characteristics and the fractal characteristics of rats primary visual cortex neurons response signal under the modulation of the orientation information in non-classical receptive field are studied by nonlinear dynamic analysis method. The main contents are as follows:(1) The scope and integration feature of non-classical receptive field was determined. First of all, the center of the receptive field was determined by the checkerboard stimulation mode, the best neural response stimulation parameters was measured by the full screen grating stimulation mode; Then, according to the receptive field position and optimal stimulation parameters, the scope of the receptive field and non-classical receptive field was determined by circular gray screen cover method; Finally, the scope of non-classical receptive field was confirmed by circular grating incremental method and further determined the integration characteristics of non-classical receptive field.(2) Extracting chaos characteristics of action potential signal under the modulation of the orientation information in non-classical receptive field, analyzed the chaotic characteristics of the mode of visual stimuli and its effect on neurons’ information transfer. First, based on electrophysiology experiment testing rats primary visual cortex neural response signals, reconstructed the phase space of action potential time interval, determined phase space reconstruction parameters. Then, according to the phase space reconstruction parameters, chaotic state of the response signal was characterized by the maximum lyapunov index. Finally, dynamic information of different chaotic states were calculated with recursive algorithm. The analysis results show that: the maximum lyapunov index can be more reliable characterization of visual stimuli under the modulation of the orientation information in non-classical receptive field. Chaos of response signal under the modulation of the orientation information in non-classical receptive field was enhanced, help to improve the efficiency of neuron information transmission.(3) Extracting fractal characteristics of action potential signal under the modulation of the orientation information in non-classical receptive field, analyzed the nonlinear correlation between neurons and its effect on the inhibition modulation of non-classical receptive field. First, two neurons with overlapping receptive field was chosen as the analysis object, fractal characteristics between two neurons response signal was characterized by multifractal detrended cross-correlation analysis method, the nonlinear correlation between neurons was characterized by fractal features, analyzed the connectivity under the modulation of the orientation information in non-classical receptive field with nonlinear correlation characteristics; Then, the fractal characteristics was compared with the correlation coefficient characteristics that obtained by conventional cross-correlation analysis, the advantage of fractal features on the characterization of visual stimuli was analyzed; Finally, the relationship between connectivity and non-classical receptive field inhibition modulation was analyzed. The analysis results show that: the modulation of the orientation information in non-classical receptive field helps to enhance the nonlinear correlation between neurons,the connectivity between neurons is stronger; Suppression modulation effect was influenced by the change of the fractal characteristics under the modulation of the orientation information in non-classical receptive field; The connection between two neurons is stronger, the inhibition of non-classical receptive field is relatively close.