Response Analysis Method For Closed-loop Feedback Of Retinal Electrical Stimulation

Visual perception is the most important way for humans to obtain the outside information.Currently,retinal degenerative diseases can lead to the damage or even loss of visual function,which greatly affects the daily life of human beings.Retinal prosthesis has been used as an effective method to solve the above problems.Artificial devices are used to detect light information and convert it into electrical signals,and then transmit the electrical signals to the unaffected areas of neurons in the inner retina,which evokes downstream visual pathways and helps patients restore visual perception.However,current retinal prostheses suffer from low resolution and non-selective activation of the visual pathway.Due to the fabrication limit on electrode density and quantity,the retinal prosthesis has poor visual resolution.In addition,it is difficult to select the optimal stimulation strategy to activate ganglion cells,and the parameter optimization process suffers from complexity and low time efficiency,which greatly reduces the performance of the patient’s visual perception.Therefore,these problems are the key challenges for the clinical promotion of retinal prostheses.1.Explore the electrical stimulation experiments of mouse retinal ganglion cells under different strategies.Aiming at increasing visual resolution of retinal prostheses,a multi-electrode array is used for electrical stimulation and signal recording.The stimulus samples were 6 C57BL/6J wild-type mice and RD10 mice with retinal photoreceptor degenerated.Subsequently,some manual software is used to analyze and visualize the experimental data,which can initially explore the electrical response characteristics of retinal ganglion cells.Based on these works,the study established a mouse retinal electrical response database,which provided data support for subsequent work,and determined the reference standard for spike sorting and electrical response analysis.2.Due to the cumbersome operation and subjectivity of the manual operation software,an objective and simple spike sorting algorithm is proposed.In this method,wavelet transform and nonlinear energy operator are used to detect spikes in neural signals,principal component analysis method extracts the features of the detected spikes,and Gaussian mixture model performs clustering to output RGC units.Compared with the results of manual operation software,it can prove that the proposed spike sorting algorithm has the advantages of reliability,fast processing and generalization ability.Therefore,this method greatly improves the time efficiency of spike sorting,reduces the complexity of high-density electrode array recording signals,and provides guidance for real-time data processing and parameter optimization of closed-loop stimulation retinal prostheses in the future.3.In retinal prostheses,ganglion cells are difficult to be selectively activated,so it is necessary to explore the electrical response characteristics of retinal ganglion cells under different electrical stimulation strategies.Based on the spike sorting results in the previous study,the raster plot and time histogram drawn by the spike distribution were used to statistically analyze the response state and the corresponding proportion of retinal ganglion cells.Based on the above,the relationship between electrical stimulation parameters and electrical response characteristics has been explored in detail.This study provides guidance for the optimization strategy of electrical stimulation parameters,and provides a theoretical basis for improving the performance of retinal prostheses.In response to the current challenges of retinal prostheses,this study explores the scientific content related to the performance improvement for the retinal prosthesis.Through animal experiments,the electrical response dataset of retinal ganglion cells was established.In addition,an adaptive spike sorting algorithm was proposed to improve the efficiency of electrical response analysis.Finally,the relationship curve between electrical response analysis and electrical stimulation strategy can provide theoretical guidance for optimizing electrical stimulation and retinal prosthesis performance strategies.