Halupka Kerry J, Shivdasani Mohit N, Cloherty Shaun L, Grayden David B, Wong Yan T, Burkitt Anthony N, Meffin Hamish
NeuroEngineering Laboratory, Department of Electrical & Electronic Engineering, The University of Melbourne, VIC 3010, Australia. National ICT Australia, Victoria Research Lab, The University of Melbourne, VIC 3010, Australia. Bionics Institute, 384-388 Albert St, East Melbourne, VIC 3002, Australia.
J Neural Eng. 2017 Feb;14(1):016006. doi: 10.1088/1741-2560/14/1/016006. Epub 2016 Nov 30.
Simultaneous electrical stimulation of multiple electrodes has shown promise in diversifying the responses that can be elicited by retinal prostheses compared to interleaved single electrode stimulation. However, the effects of interactions between electrodes are not well understood and clinical trials with simultaneous stimulation have produced inconsistent results. We investigated the effects of multiple electrode stimulation of the retina by developing a model of cortical responses to retinal stimulation.
Electrical stimuli consisting of temporally sparse, biphasic current pulses, with amplitudes sampled from a bi-dimensional Gaussian distribution, were simultaneously delivered to the retina across a 42-channel electrode array implanted in the suprachoroidal space of anesthetized cats. Visual cortex activity was recorded using penetrating microelectrode arrays. These data were used to identify a linear-nonlinear model of cortical responses to retinal stimulation. The ability of the model to generalize was tested by predicting responses to non-white patterned stimuli.
The model accurately predicted two cortical activity measures: multi-unit neural responses and evoked potential responses to white noise stimuli. The model also provides information about electrical receptive fields, including the relative effects of each stimulating electrode on every recording site.
We have demonstrated a simple model that accurately describes cortical responses to simultaneous stimulation of a suprachoroidal retinal prosthesis. Overall, our results demonstrate that cortical responses to simultaneous multi-electrode stimulation of the retina are repeatable and predictable, and that interactions between electrodes during simultaneous stimulation are predominantly linear. The model shows promise for determining optimal stimulation paradigms for exploiting interactions between electrodes to shape neural activity, thereby improving outcomes for patients with retinal prostheses.
与交错式单电极刺激相比，多电极同时进行电刺激在使视网膜假体引发的反应多样化方面已显示出前景。然而，电极之间相互作用的影响尚未得到充分理解，同时刺激的临床试验结果也不一致。我们通过建立视网膜刺激的皮质反应模型，研究了视网膜多电极刺激的效果。
由时间上稀疏的双相电流脉冲组成的电刺激，其幅度从二维高斯分布中采样，通过植入麻醉猫脉络膜上腔的42通道电极阵列同时传递到视网膜。使用穿透式微电极阵列记录视觉皮质活动。这些数据用于确定视网膜刺激的皮质反应的线性 - 非线性模型。通过预测对非白色图案刺激的反应来测试模型的泛化能力。
该模型准确预测了两种皮质活动指标：多单元神经反应和对白噪声刺激的诱发电位反应。该模型还提供了有关电感受野的信息，包括每个刺激电极对每个记录位点的相对影响。
我们展示了一个简单的模型，该模型准确描述了脉络膜上视网膜假体同时刺激时的皮质反应。总体而言，我们的结果表明，视网膜同时多电极刺激的皮质反应是可重复和可预测的，并且同时刺激期间电极之间的相互作用主要是线性的。该模型有望确定最佳刺激范式，以利用电极之间的相互作用来塑造神经活动，从而改善视网膜假体患者的治疗效果。
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