Univ. Bordeaux, Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, Bordeaux, F-33405 Talence, France.
J Neurosci Methods. 2012 Jul 30;209(1):250-4. doi: 10.1016/j.jneumeth.2012.05.006. Epub 2012 Jun 4.
Penetrating neural probes are considered for neuroprosthetic devices to restore sensory or motor functions of the CNS using electrical neural microstimulation. These multielectrode systems require optimal electrode configurations to allow precise and focused tissue activation. Combining a finite element model of the spinal cord and compartmentalized models of both simple and complex neuron morphologies, we evaluated the use of the "ground surface" configuration, which consists in the integration of a conductive layer on the front side of electrode shanks, for the return of the stimulation current. Compared to the classical monopolar and bipolar configurations, this strategy resulted in a focalization of both the potential field and the threshold-distance curves. The improvement in focalization was highest for lowest impedance of the ground surface. Moreover, the gain in focality was highest on the side of the shank opposite to the electrode, so that only the neurons located in front of stimulation electrode were activated. This focalizing strategy will allow the design of new microstimulation paradigms aiming at precisely targeting the CNS with complex spatio-temporal stimulation patterns, which could benefit to future stimulation-based neuroprosthesis.
穿透式神经探针被认为是神经假体设备的一种，可通过电神经微刺激来恢复中枢神经系统的感觉或运动功能。这些多电极系统需要优化的电极配置，以允许精确和集中的组织激活。我们结合了脊髓的有限元模型和简单及复杂神经元形态的分区模型，评估了“接地表面”配置的使用，该配置包括在电极柄的前侧集成一个导电层，以返回刺激电流。与经典的单极和双极配置相比，这种策略导致了电位场和阈值距离曲线的聚焦。对于最低的接地表面阻抗，聚焦的改善程度最高。此外，在与电极相反的柄侧获得的聚焦增益最高，因此只有位于刺激电极前面的神经元被激活。这种聚焦策略将允许设计新的微刺激范式，旨在使用复杂的时空刺激模式精确靶向中枢神经系统，这将有益于未来基于刺激的神经假体。
