Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju 220-710, Korea.
Korean J Physiol Pharmacol. 2009 Dec;13(6):443-8. doi: 10.4196/kjpp.2009.13.6.443. Epub 2009 Dec 31.
For successful visual perception by visual prosthesis using electrical stimulation, it is essential to develop an effective stimulation strategy based on understanding of retinal ganglion cell (RGC) responses to electrical stimulation. We studied RGC responses to repetitive electrical stimulation pulses to develop a stimulation strategy using stimulation pulse frequency modulation. Retinal patches of photoreceptor-degenerated retinas from rd1 mice were attached to a planar multi-electrode array (MEA) and RGC spike trains responding to electrical stimulation pulse trains with various pulse frequencies were observed. RGC responses were strongly dependent on inter-pulse interval when it was varied from 500 to 10 ms. Although the evoked spikes were suppressed with increasing pulse rate, the number of evoked spikes were >60% of the maximal responses when the inter-pulse intervals exceeded 100 ms. Based on this, we investigated the modulation of evoked RGC firing rates while increasing the pulse frequency from 1 to 10 pulses per second (or Hz) to deduce the optimal pulse frequency range for modulation of RGC response strength. RGC response strength monotonically and linearly increased within the stimulation frequency of 1~9 Hz. The results suggest that the evoked neural activities of RGCs in degenerated retina can be reliably controlled by pulse frequency modulation, and may be used as a stimulation strategy for visual neural prosthesis.
为了成功地通过电刺激实现视觉假体的视觉感知，基于对视网膜神经节细胞（RGC）对电刺激反应的理解，开发有效的刺激策略至关重要。我们研究了 RGC 对重复电刺激脉冲的反应，以开发一种使用刺激脉冲频率调制的刺激策略。将来自 rd1 小鼠光感受器退化视网膜的视网膜贴片附着到平面多电极阵列（MEA）上，并观察到对各种脉冲频率的电刺激脉冲串的 RGC 尖峰反应。当脉冲间隔从 500 到 10 毫秒变化时，RGC 反应强烈依赖于脉冲间隔。尽管随着脉冲率的增加，诱发的尖峰被抑制，但当脉冲间隔超过 100 毫秒时，诱发的尖峰数>最大反应的 60%。基于此，我们在将脉冲频率从 1 增加到每秒 10 个脉冲（或 Hz）的同时，研究了诱发 RGC 放电率的调制，以推断出调制 RGC 反应强度的最佳脉冲频率范围。在 1~9 Hz 的刺激频率范围内，RGC 反应强度单调且线性增加。结果表明，退化视网膜中 RGC 的诱发神经活动可以通过脉冲频率调制可靠地控制，并且可以用作视觉神经假体的刺激策略。
