本文選題：視覺假體 + 電刺激參數�。� 參考：《上海交通大學》2012年博士論文

【摘要】：人類認識外界世界的信息至少有70%是通過視覺系統提供，失明不但嚴重影響了患者的生活質量，而且給社會帶來了很大負擔。隨著科學技術的不斷發(fā)展，用人工視覺假體修復盲人視覺功能成為全世界研究的熱點。中國的視覺假體研究小組提出了刺入式視神經視覺假體這一新型人工視覺修復方案，目前這一方案有待于系統的研究。本課題主要對視神經電刺激在視覺皮層誘發(fā)的響應特征進行了系統的分析，并對不同的刺激波形和刺激參數在視神經電刺激中的作用應用皮層誘發(fā)電位進行了評估。針對視網膜假體，我們小組自主研發(fā)了適合植入脈絡膜上腔對視網膜進行電刺激的基于Micro-electro-mechanical System (MEMS)的聚酰亞胺薄膜多電極陣列。本課題對這一刺激電極陣列的可行性及其在視覺皮層誘發(fā)電位的時間和空間特性進行了初步的探索。具體內容如下： 在視神經電刺激研究中，，我們采用自制鉑銥合金絲電極陣列對視神經纖維進行微電流刺激，并在初級視覺皮層放置銀球電極陣列記錄誘發(fā)的視皮層響應信號，系統地研究了視神經電刺激波形和刺激參數對視覺皮層誘發(fā)的多波響應電位的時空特性影響，獲得了視神經電刺激誘發(fā)的皮層響應中不同波形成分的閾值信息以及優(yōu)化的刺激參數信息，為理解視覺信息的傳遞過程及進一步優(yōu)化視神經視覺假體刺激參數提供了實驗依據。主要結果包括：（1）通過微電流刺激視神經纖維，可以在視覺初級皮層誘發(fā)含有多個波形成分的場電位，最多時可記錄到P0，N1，P1，P2和P3五個波形成分。不同的波形成分具有不同的閾值和時間特性。閾值越低的成分潛伏期和持續(xù)時間都越短。（2）在視神經顳背側象限內電刺激視神經纖維，對皮層多電極記錄的快波響應（P1）與皮層視野拓撲對應關系圖比較，發(fā)現視皮層響應最大的區(qū)域與電刺激視神經部位對應的視野一致。證明靠近眼球部位的視神經保持了較好的視覺拓撲對應關系，適合植入視覺假體。（3）刺激的波形和參數對視神經電刺激誘發(fā)的視皮層響應具有重要的影響。與對稱的電荷平衡刺激波形相比，具有窄高負相脈沖和寬矮正相脈沖的非對稱波形可以降低電刺激的閾值。在同樣刺激電荷密度下誘發(fā)較大響應的刺激波形其誘發(fā)響應的空間分布范圍也較大。在刺激波形兩脈沖相位之間加入時間間隔可以降低刺激閾值，時間間隔為0.2ms時達到飽和；對稱的先負后正刺激波形加入時間間隔后能夠誘發(fā)最大的響應。隨著刺激頻率的升高，皮層誘發(fā)響應的幅值呈下降趨勢；不同波形成分隨著刺激頻率的升高變化規(guī)律不同。這些實驗結果對于開發(fā)研制視神經視覺假體提供了實驗依據。 在脈絡膜上腔電刺激研究中，我們將60刺激位點的MEMS薄膜電極植入到脈絡膜上腔對視網膜進行電刺激，驗證了刺激電極陣列的有效性，并通過記錄分析初步探討了皮層多通道誘發(fā)響應的時空特性。結果顯示脈絡膜上腔微電流刺激能夠成功誘發(fā)視覺皮層響應，單個刺激電極的電流閾值為48.57±6.90μA，對應的電荷密度為25.24±3.59μC/cm2；整排電極（10個刺激位點）的電流閾值為25.55±5.43μA，對應的電荷密度為13.28±2.82μC/cm2。刺激電流與電荷密度閾值皆位于刺激電極和被刺激組織的安全刺激范圍內。隨著刺激電流強度的增強，皮層誘發(fā)響應的幅值增大，皮層響應范圍不斷增加，但最大響應位點保持不變，具有一致性和穩(wěn)定性。不同的刺激電極（最小距離為750μm）可在視皮層不同位置誘發(fā)響應，證明脈絡膜上腔電刺激具有一定的空間對應性。本項研究進一步驗證了脈絡膜上腔電刺激的可行性和有效性，量化了電刺激的一些參數，為脈絡膜上腔視覺假體電刺激參數設計提供了參考。
[Abstract]:At least 70% of the human knowledge of the outside world is provided by the visual system. Blindness not only seriously affects the quality of life of the patients, but also brings a great burden to the society. With the continuous development of science and technology, the use of artificial visual prosthesis to repair the visual function of the blind has become a hot spot in the world. The research of visual prosthesis in China is small The group proposed a new artificial visual prosthesis of the spiny optic optic visual prosthesis. The present scheme needs to be studied systematically. This topic mainly analyzes the response characteristics of the optic nerve electrical stimulation in the visual cortex, and the effect of different stimulus waves and stimulation parameters on the optic nerve electrical stimulation. For the retinal prosthesis, we independently developed a polyimide polyimide array based on Micro-electro-mechanical System (MEMS), which is suitable for electrical stimulation of the retina in the upper choroidal cavity. The feasibility of this array of electrodes and the visual cortex induced by this topic. The temporal and spatial characteristics of the potential were preliminarily explored.
In the study of optic nerve electrical stimulation, we used a self-made platinum iridium alloy electrode array to stimulate the optic nerve fibers and recorded the evoked visual cortex response signals in the primary visual cortex. We systematically studied the waveform of the electrical stimulation of the optic nerve and the multiwave response induced by the prickling parameters to the visual cortex. The threshold information of different waveform components in the cortical response induced by optic nerve electrical stimulation and the optimized stimulus parameters are obtained, which provide experimental basis for understanding the transmission process of visual information and further optimizing the stimulus parameters of the optic vision prosthesis. The main results include: (1) through the micro current stimulation The optic nerve fibers can induce a field potential containing multiple waveform components in the visual primary cortex. At most, P0, N1, P1, P2 and P3 can be recorded. The different waveform components have different threshold and time characteristics. The lower the threshold and the duration of the component, the shorter the duration and duration of the component. (2) the electrical stimulation in the temporal dorsal quadrant of the optic nerve The optic nerve fibers, comparing the fast wave response recorded by the cortical multi electrode (P1) and the topological mapping of the cortical field, found that the region with the greatest response to the visual cortex was consistent with the visual field corresponding to the electrical stimulation of the optic nerve. It was proved that the optic nerve near the eyeball maintained a better visual topological correspondence and was suitable for implantation of visual prosthesis. (3) thorns. The excited waveforms and parameters have an important effect on the visual cortex response induced by the optic nerve electrical stimulation. Compared with the symmetrical charge balance stimulation waveform, the asymmetric waveform with the narrow negative phase pulse and the wide short positive phase pulse can reduce the threshold of the electrical stimulation. The stimulus wave induced by the same stimulus charge density is induced. The spatial distribution of the response is also larger. Adding time interval between the two pulse phase of the stimulus wave can reduce the threshold of stimulation, the time interval is 0.2ms, and the maximum response can be induced after the symmetrical first negative positive stimulus wave is added to the time interval. With the increase of the frequency of stimulation, the amplitude of cortical evoked response is lower. The variation of different waveform components with the increase of the frequency of stimulation is different. These experimental results provide an experimental basis for the development and development of optic nerve visual prosthesis.
In the study of the choroidal upper cavity electrical stimulation, we implanted the MEMS film electrode of the 60 stimulation site into the upper choroidal cavity to stimulate the retina. The effectiveness of the stimulus electrode array was verified. The temporal and spatial characteristics of the cortical multichannel induced response were preliminarily investigated by recording and analysis. The results showed that the microcurrent stimulation in the choroid cavity was able to be stimulated. The visual cortex response was successfully induced. The current threshold of the single stimulus electrode was 48.57 + 6.90 A, the corresponding charge density was 25.24 + 3.59 mu C/cm2, and the current threshold of the whole electrode (10 stimulation sites) was 25.55 + 5.43 mu A, and the corresponding charge density was 13.28 + 2.82 mu C/cm2. and the charge density threshold was both at the stimulation electrode and the stabbed electrode. The amplitude of cortical evoked response increased with the increase of stimulation current intensity, and the response range of cortex increased, but the maximum response site remained unchanged, with consistency and stability. Different stimulus electrodes (the minimum distance of 750 u m) could induce response in different positions of the visual cortex, and the choroid was proved to be on the choroid. This study further validates the feasibility and effectiveness of the electrical stimulation of the choroidal cavity, quantifies some parameters of the electrical stimulation, and provides a reference for the design of the electrical stimulation parameters for the visual prosthesis of the choroidal cavity.
【學位授予單位】：上海交通大學
【學位級別】：博士
【學位授予年份】：2012
【分類號】：R774.6

【參考文獻】

相關期刊論文 前1條

1 吳開杰;柴新禹;李麗明;陸一j;任秋實;;基于視神經的視覺假體研究與設計[J];中國科學(G輯:物理學 力學 天文學);2007年S1期

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