人工视觉假体诱发视皮层轮廓方位感知的神经机制研究

Artificial visual prosthesis, a way to restore the vision function of the blind by multi-site electrical stimulations, has become one of the world promising frontier technologies. However, the lack of the neural mechanism study, particularly those underlying whether and how retinal multi-site electrical stimulations could elicit different types of visual cortical neurons become the bottle neck in the further development of visual prosthesis. Orientation-selective neurons in the early visual cortices of high mammalians including human are well-known contour detectors, because they encode the contour orientation information and thus serve as the neural basis for form vision involving initially an edge or contour discrimination. In this project, combining model simulation, single-cell and population recordings from cat primary and secondary visual cortices, we will thoroughly investigate: 1. the neuronal mechanisms underlie the activation of orientation-selective neurons by stimuli of flashing gratings/contours and multi flashing spots. 2. Whether and how discrete retinal multi-site electrical stimulations could evoke similar visual responses of orientation-selective neurons. The results and findings will unravel the integrative neural mechanisms of orientation-selective neurons underlying visual prosthesis for contour or object recognition, thus, will provide direct neuronal basis for the advanced improvement of visual prosthesis.

人工视觉假体是一种新兴的通过多位点电刺激修复盲人视觉功能的方法。随着电子技术的高速发展，视觉假体的构造越来越精密，但是，目前对多位点电刺激是如何诱发视皮层不同功能性神经元的反应及其神经机理研究的极度缺乏，限制了视觉假体的发展和成功。视觉方位选择性神经元是灵长类早期视皮层最主要的功能性神经元之一，它是人类进行物体轮廓感知和识别的神经基础。多位点电刺激是否能够以及如何诱发视皮层神经元的方位选择性反应，并进而编码外部物体的轮廓方位信息，这一基础神经科学问题的研究至今未见报道。针对视觉假体基础研究匮乏的瓶颈问题，本课题结合计算机仿真、神经电生理和内源信号光学成像实验手段，从神经科学角度出发，以经典视觉模式动物家猫的早期视皮层为研究模型，通过对比研究离散的多光点视觉刺激和视网膜多位点电刺激是如何被视觉系统整合并诱发视皮层方位选择性神经元的反应，探索和研究视觉假体修复盲人轮廓方位识别的神经整合机制。

本项目首先建立视皮层群体神经元的计算仿真模型，从理论上研究了人工视觉假体电刺激诱发的离散光点感知能否以及如何在视皮层上被整合成轮廓方位的群体细胞反应，从而激活视皮层神经元方位功能柱。然后以经典视觉模式动物家猫的早期视皮层为研究模型，通过结合在体单细胞电生理和光学功能成像研究手段，记录视皮层神经元反应，进一步研究了离散多光点视觉刺激诱发视皮层方位选择性的反应特性和规律。选用合适的电极阵列进行视网膜多位点电刺激，通过光学成像实验，探索了离散的多位点人工电刺激诱发视皮层方位选择性神经元活动的整合规律，为揭示视觉假体帮助修复盲人对物体或图形文字识别的视觉功能的神经基础提供直接的实验依据和可能的脑机整合机制。